Welcome to
the battle of CGM systems in the Grand Canyon and Las Vegas. As a warning
upfront, I have a lot to discuss so I have split this blog into two parts. You will need 15 minutes to read it, here a few pics for the warm up.
·
Part
1: This blog where I discuss the top line information and statistics with very
little fluff, so the reader only interested in find out about the different CGM
systems can consume without my anecdotes and stories.
·
Part
2: More detailed in terms of my opinion on the CGM devices, my exercise management
strategies, download pictures of where different features of the CGM devices
really came to the party, and my diabetes philosophy. It will also include a
small scattering of stories from the trip including; getting engaged at the
bottom of Grand Canyon, dancing up at the front of the Cirque Du Soliel Michael
Jackson show, and lots of photos from the trip.
I have
written this blog for a reader who has a good understanding of what type 1
diabetes is, already knows what CGM is,
has some understanding of the current products, and understands the different
alarms you can use on CGM devices. If you currently do not have this
understanding please link to the below articles, then this blog will be of much
greater value:
2. Integrated Solutions Comparison Chart
of CGM devices - produced by Gary Scheiner of Integrated Diabetes Solutions
For my
reasons for wearing four CGM devices and the aims of the experiment please read
the pre-trip article.
I was attached to four devices (Abbot Freestlye Libre, Dexcom G5, MinMed
MM640G, Minimed VEO) for fourteen days whilst trekking rim to rim in the Grand
Canyon and partying poolside at the Bellagio. Please remember whilst reading, this is a n=1 experiment and because the
CGM devices worked in a certain way for me, does not mean they will work
identically for you. Also some of the diabetes management strategies I use
may be different to yours, so please question everything (I am my own diabetes
expert, I am not yours) and consult your health care team before employing any
of them. Disclaimers over, here are the questions I endeavoured to answer;
1. Which CGM system was the the most accurate for me compared to finger
prick blood glucose (BG), and what is the practical impact of accuracy? Does
every MARD % really make a difference?:
·
Which system has the most accurate MARD %
·
Which system has the most false alarms and missed threshold limits
·
What would be the consequence of using SG (sensor glucose) readings to
correct at meal times in place of BG
2. What are the key features and unique selling points of each system and
how do they trade off against each other?
3. What rank will each CGM system get from me
in different key areas:
·
Accuracy
·
Ease of use (sensor insertion, accessing sensor information)
·
Key safety features
·
Key features for proactive management
·
Cost at manufacturers specification & at a practical
level
4. My
thoughts on the groups of people who may benefit the most from different CGM
systems, and the NHS funding landscape
Let me begin.
1. Which CGM systems is the most accurate foe me compared to finger
prick blood glucose (BG) and what is the practical impact of accuracy ?
MARD (Mean Average Relative Difference)
is the standard measurement of accuracy of SG readings compared to a
blood glucose standard. The standard I used was the blood glucose readings from
my calibrated and tested blood glucose machine (The Libre which uses Optium
strips). Real life speak; MARD is how different on average the SG reading is compared to the BG
reading. The first tale below aims to put this practically and shows the lower
the MARD % the closer the SG range is to BG, which should translate into more
effective diabetes management. The second table shows the MARD % of the four
devices over the 14 days of wear, by showing accuracy in the first seven days
of wear and if I could obtain readings after that.
Example SG
range at different MARD% and BG levels
BG
5mmol/l
|
BG
10mmol/l
|
BG
15mmol/l
|
BG
20mmol/l
|
|
MARD %
|
SG range
mmol/l
|
SG range
mmol/l
|
SG range
mmol/l
|
SG range
mmol/l
|
5%
|
4.8 - 5.2
|
9.5 - 10.5
|
14.3 - 15.7
|
19.0 - 21.0
|
10%
|
4.6 - 5.4
|
9.0 - 11.0
|
13.5 - 16.5
|
18.0 - 22.0
|
15%
|
4.4 - 5.6
|
8.5 - 11.5
|
12.8 - 17.2
|
17.0 - 23.0
|
20%
|
4.2 - 4.8
|
8.0 - 12.0
|
12.0 - 18.0
|
16.0 - 24.0
|
My 14 days
trail MARD % for all four CGM devices (6th - 19th August 2016)
Device & number of sensors used
in trial period
|
MARD %
First 7 days after insertion
|
MARD %
Days 7-10 after insertion
|
Advertised MARD % from manufacturers
Average (SD)
|
Libre
1 sensor
|
16%
|
9%
|
11%
|
G5
2 sensors
|
10%
|
27%
|
9%
|
*MM640G
2 sensors
|
14%
|
N/A
|
*14%
|
VEO
2 sensors
|
13%
|
N/A
|
13%
|
*Please note the MM640G
I used had the old Guardian Link Transmitter, which has now been superseded by
an updated version with a new algorithm that is reported to have a MARD of 9%.
I was not aware of this until I returned home. Medtronic are sending me an
updated Guardian Link Transmitter which I will wear and report back.
The table above shows the MARD % for the different devices. In the first
seven days after sensor insertion, the manufacturer's suggested usage time for
G5, VEO (6days), MM640G (6 days), it is clear that the G5 was the most accurate
with a MARD of 10%, although all performed pretty much to manufacturers
specifications. The Libre MARD was higher in the first seven days, but you can
see the accuracy really improved after seven days. Unfortunately my perfuse
sweating in the Grand Canyon heat of 40+ Celsius caused it to come off. I would
not be surprised to see an overall MARD of around the 11% by day fourteen if
the Libre would have stayed on. Both the MM640G and VEO use the Enlite sensor,
and they both stopped working after 7 days and a second sensor was inserted for
the next seven days. The G5 continued to work days 7-10 then died, I then
inserted a second sensor. You can see that the accuracy of the G5 after day 7
deteriorated significantly, making the readings very unreliable.
My conclusion in terms MARD % accuracy are:
1. All CGM systems performed close to advertised accuracy and did a good
job
2. The G5 was the most accurate in the seven days after insertion
3. The Libre showed great promise in accuracy for the full fourteen days, but keeping it in place was an issue, despite Skin Tac and Tegaderm. Please bear in mind I was in 40+ Celsius heat and when wearing in the U.K previously, the Libre sensors have lasted the full 14 days with a MARD of about 11-12%.
4. I could not get the sensors to go past advertised manufacturers time
accurately. This may have been due to the environmental condition. I would not
be keen to make therapy decisions based on the SG readings after seven days for
G5 when MARD % increased, as you will see below, every MARD % counts when it
comes to therapy decisions.
MARD % means very little until you put it into real life situations, the main two being:
1. What impact does a MARD have on the number of false alarms and missed hypos?
2. What happens if you bolus using the SG reading, do you suffers hypos and highs, does every MARD % matter?
I aim to run my blood glucose level 3.5 - 9.0 mmol/l to attain as near
normal HbA1c as possible, usually ranges 5.8 - 6.4%, whilst preventing
excessive hypoglycaemia. The download of BG readings below shows in the
fourteen days I had four episodes <3.5mmol/l and only two readings
>9.0mmol/l. The sensor downloads of the 14 days confirms the same picture.
Blood Glucose Download (6th - 19th August 2016)
CGM Download downloads for all four devices (6th - 19th August 2016)
I do not show these to gloat, but to show the power of having CGM to
inform my diabetes decisions, and alert me when a glucose excursion is coming.
This level of control was only possible because I set alarms on the CGM systems
(you cannot set alarms on the Libre). I have evolved to using only the below
alarms from years of trial error, they suit me and my management but may not
necessarily be ideal for you:
·
Low limit was set at 4.2mmol/l on G5, MM640G and VEO. This meant every
time the sensor level hit 4.2mmol/l on the different CGM systems, I got an
alarm. This usually gives me time to take action to prevent a <3.5mmol/l,
and does not annoy me with too many alarms in a day. I do not get huge swings
and drops so i can get away without predictive alarms and not setting the lower
limit to high. If i was a "swinger" i would have the predictive
alarms on or set the lower limit around 5.0mmol/l. As you can imagine with
three systems it was a good job they have a vibrate option otherwise my fiancé
and other trek team members would not have been happy!
·
High limit set at 9.0mmol/l. I bolusing for food pre-meal by at least 15
minutes and choose meals that do not cause significant post meal spikes. If I
was a Frostie muncher or sugar addict I would be setting this level at
something like 14mmol.l. You need to make the alarms work for your lifestyle
·
As mentioned above I do not set any predictive alerts or rise/fall
alerts because previous experience has taught me that this is overkill, and
leads to extreme alarm fatigue! I have found from trial and error that if I set
my low limit 1.2mmol/l above my hypo range I usually do not miss hypos.
·
I will discuss the use of Low Glucose Suspend and SmartGuard (predictive
low glucose suspend) in the features section. They were not set routinely, only
for demonstration purposes on certain days.
What impact does a MARD have on the number of false alarms and missed
hypos?
I reviewed all of the downloaded information to look at how many false
alerts at 4.2mmol/l and 9.0mmol/l I got with each system, and how many missed
highs and hypos there were. The Libre does not have alert facilities, but i
took the liberty of running the stats to show what would have happened if they
did. The graph below shows the results:
Number of false alerts and missed highs and hypos for all four devices in
14 days
(6th - 19th August 2016)
*Please note the MM640G
I used had the old Guardian Link Transmitter, which has now been superseded by
an updated version with a new algorithm that is reported to have a MARD of 9%.
I was not aware of this until I returned home. Medtronic are sending me an
updated Guardian Link Transmitter which I will wear and report back.
Summary of the false alerts and missed highs and hypos:
·
Although the Libre does not have
any alarms I pulled the data to show what would have happened if it did. The
Libre had a tendency to be running higher than the BG, evidenced by the highest
number of false alerts at 9.0mmol.l e.g. the Libre was reading above 9.0mmol/l
but the BG was below. There were only three false alerts at 4.2mmol/l, e.g. the
Libre was reading 4.2mmol/l or below but the BG was higher. There would have
been three missed hypos if my hypo level was 3.9mmol/l but none at my actual
hypo level of 3.4mmol/l, so all hypos could have been prevented.
·
The G5 shows why a MARD of 10% vs 13+% is so important. The G5 had
virtually no false or missed high alarms, only three false alarms at 4.2mmol/l
and no missed hypos at 3.4mmol/l. This
shows that when it comes to alarms and preventing hypos, every MARD % counts.
·
The MM640G and VEO performed almost identically with very few issues
with high alarms but a ten false low alarms at 4.2mmol/l, almost one per day,
and the highest number of missed hypos at <3.5mmol.l, three and one
respectively.
During my time as a medical device educator and now as a diabetes
educator, I have started a lot of people on CGM systems. The number one annoyance
reported back is the number of alarms and especially false alarms, this is why accuracy
is key. If you get lots of false alarms, it is like the boy who cries wolf too
often - when the real cry comes it is ignored and issues happen. The above data
shows that every MARD % counts for preventing false alarms, and for me the G5 clearly comes out on top.
What
happens if you bolus using the SG reading, does MARD % matter?
The G5 has
both CE mark and FDA approval for people with
diabetes to use the SG readings for treatment decision. The Libre has CE mark for
similar as the G5 and has submitted to the FDA for approval. The VEO and MM640G
do not have CE mark or FDA approval for the above at present. The wording of
the approval for G5 and Libre is similar but practically it has very different
application. I will show the detail from CE & FDA approval G5 and CE mark
Libre, and explain in real life terms what it means:
G5
·
*If your glucose alerts and readings do not match your
symptoms or expectations, you should obtain a finger stick. A minimum of two
finger sticks a day is required for calibration.
·
For children aged 2 and above and decisions to be made
by a competent adult
Real life speak: As long as the user is
confident in the SG accuracy when they do the two calibrations per day, they
can without need for a confirmatory BG;
·
Bolus from the SG reading
·
Treat hypoglycaemia
·
Review data and change insulin doses accordingly
·
Make exercise plan adjustments based on the SG reading
Libre
·
(1) A finger prick
test using a blood glucose meter is required during times of rapidly changing
glucose levels when interstitial fluid glucose levels may not accurately
reflect blood glucose levels or if hypoglycaemia or impending hypoglycaemia is
reported by the System or when symptoms do not match the System readings
·
For children aged 4 and above and decisions to be made
by a competent adult
Real life speak: As long as the Libre does not
have a an arrow going straight up or down the reading can be used for:
·
Bolus from the SG reading
·
Make exercise plan adjustments based on the SG reading
·
Review data and change insulin doses accordingly
However,
·
If there is a arrow going straight up or down you cannot use the SG to
calculate the correction dose at meal times, you must use a BG
·
If the reading says you are
hypoglycaemic or hypoglycaemia is impending e.g. a SG reading of 5.5 with a
straight arrow down, you must confirm with
BG
By just
reading the internet you could be excused for thinking (I excused myself!) they
both had the same clinical indications, but in practical terms they are very
different. That might be due to the fact the G5 has a 2% better MARD as
reported by the manufacturers. The data below will shed some light on what that
meant to me, along with the already reviewed alarm data. I am not naive in
thinking people with diabetes will follow the clinical indication to the
letter, however, often there is a good reason why certain safety specifications
are set. Let us see what it meant for me.
With this
in mind I looked to see if using the SG reading from all the different devices
at meal times to correct to a level of 5.6mmol/l would impact on my control. The
measure I used was; for all of the bolus's in the fourteen days, what
percentage of bolus's would end up in a specific target range the BG achieved:
·
within 1mmol/l of 5.6mmol/l (4.6 - 6.6mmol/l)
·
within 1.6mmol/l of 5.6mmol/l (4.0
- 7.2mmol/l)
·
within 2mmol/l of 5.6mmol/l (3.6 - 7.6mmol/l).
The below graph shows the results:
Percentage accuracy of correction bolus in target using SG of four CGM
devices in 14 days
(6th - 19th August 2016)
*Please note the MM640G
I used had the old Guardian Link Transmitter, which has now been superseded by
an updated version with a new algorithm that is reported to have a MARD of 9%.
I was not aware of this until I returned home. Medtronic are sending me a
updated Guardian Link Transmitter which I will wear and report back.
Summary of using SG readings to bolus from:
·
If aiming to keep within 1mmol/l of 5.6mmol/l (4.6-6.6mmol/l), using the SG reading would
not be accurate enough for me. At best the G5 would hit that target 75% of the
time and MM640G 60% of the time. This would mean one to two bolus's per day would
go out of target.
·
If aiming to keep within 1.6mmol/l of 5.6mmol/l (4.0-7.2mmol/l), using
the SG reading from Libre, MM640G, and VEO would not be good enough for me. At
best I would hit that target 80% of the time, which would mean one bolus per
day would go out of target. The G5 would be in the target 95% of the time and
only one bolus in four days would go outside the range; this would be good
enough for me.
·
If aiming to keep within 2.0 mmol/l of 5.6mmol/l (3.6-7.6mmol/l), using
the SG reading from all SG devices would probably be good enough for me, as 90-95%
would be in target, meaning one bolus every two to four days would go out of
target.
·
This data again suggests that a small improvement in MARD % makes a
difference in bolus precision for me. In
practical terms for me;
o I would be happy to correct to
5.6mmol/l for G5. If I was a paediatric
that would be 6.0mmol/l.
o I would be happy to correct to
6.0mmol/l for Libre, VEO and MM640G and if I was a paediatric, 6.4mmol/l.
2. What are the key features and
unique selling points of each and how do they trade off against each other?
For each device I will discuss the key features that make the difference for
me, along with the limitations and potential future alterations that would
make them more suitable for me. I am not going to list every feature,
you can go to the company's websites for that, and they are linked to in their
respective sections. Each company has a variety of different data sharing
APP's, receivers, and other innovations that I will touch on briefly. If you
are into the data sharing on different devices, which is especially good for
parents, please see the Nightscout website.
In my opinion the mothers, fathers, grandparents and relatives that have made
data sharing possible via Nightscout deserve praise of the highest order! I
love #WeAreNotWaiting, tip of the cap to you all!
What I loved:
1. It was the easiest
sensor to insert, it was the quickest to set up, and it was the quickest to
start working at 60 minutes.
2. No finger stick BG
calibrations required due to their factory calibration method.
3. It is also a blood
glucose meter, ketone meter, and does have a bolus calculator if unlocked by a
HCP code. This has the potential to be a
full all-in-one BUT, read the limitations part.
4. The arrows showing the
direction the glucose is going is very helpful in preventing highs and lows.
Read part 2 on how I used the arrows to manage exercise, prevent hypos and
change bolus amounts.
5. As long as you scan
every 8 hours you get a full profile of the full fourteen days. This allows you
to:
a. Use the Libre
History Graphs to identify glucose excursion patterns that need therapy change,
and to monitor progression.
b. Download to the
Libre Software or Diasend so a comprehensive analysis can be performed to
optimise control.
6. Now has an Andriod LibreLink
APP
so you can scan with your phone. Anything that goes on the phone is a bonus and
I am never without mine, BUT, I am an Apple man so on the iPhone please!
The limitations and
potential solutions:
1. There are no alarms
to warn if you hit a low or high threshold. A few times I scanned and I was
already <3.5mmol/l and >9.0mmol/l. Whereas the CGM devices with alarms
would have warned me at 4.2mmol/l and 9.0mmol/l, respectively. On the Grand
Canyon trip especially, this would have caused me significant problems as I
would have had to scan the Libre every 20 minutes to be safe, and it would have
offered no protection through the night. To test this theory I turned all
alarms off for two days to see if I could manage on the Libre scans alone, the
download is below. You can see I missed a hypo on the 14th at 13:00 and a long
one through the night on the 15th. For me, I manage my diabetes very
proactively and the alarms at 4.2mmol/ and 9.0mmol/l are an absolute essential.
However, for somebody else who wants to reduce the number of finger pricks, have
trend arrows to help prevent issues, and not to be alarmed at during the day,
this may be perfect. The obvious solution is for future models to have the
option of alarms.
2. It is almost an
all-in-one as you can unlock a bolus calculator with a HCP code that allows you
to put in carb ratios, sensitivity factors etc. This allows calculation of meal
time bolus amounts. However, you cannot use the scanned Libre reading to give a
correction and you must do a BG reading on the Libre to access it. Also, you
cannot just enter carbs as you need to do a BG to activate the bolus
calculator. This pretty much renders it useless for me as a bolus calculator. Obviously if you know your carb
ratios, sensitivity factors etc, at different times of day, you can work it out
in your head. But be careful here doing this with CGM because you will probably
not be taking into account insulin on board when correcting in between meals,
and the Libre does not show you this. I know a lot of people, including me, who
have got giddy one hour post meal having seen a high SG reading and given a
correction, later to be found chugging Lucozade! On a side note, in my opinion
the ROCHE Bolus Advisor has the best bolus calculator as it takes into account
both glucose centric and meal centric insulin and this allows a better calculation
of true insulin on board. The obvious solution is to allow scanned Libre
readings to be entered into the bolus calculator (as long as they are not very
fast moving ones!), show insulin on board, and consider the algorithm used for
calculating insulin on board.
3. The fact it lasts
14 days is amazing but that is only amazing if it stays on for 14 days. Some
tips I have picked up are:
a. Put the sensor on
the inside of the back arm so you do not bang or catch it on doors
b. Use Skin Tac before
applying the sensor
c. Wear bandage,
tegaderm or other apparel to keep it secure
4. I love the fact you
do not have to do calibrations, but if you are doing BG results anyway (confirm
hypo, SG moving rapidly) it would be nice to have the option to calibrate, as
this would help improve the accuracy. There is a Glimp APP that allows this,
and anecdotally I have heard the MARD is better than 11%! See Nightscout for
details.
I am an Apple man so have not had the chance to give it a go but take a look
here.
What I loved:
1. As discussed above,
I loved the accuracy and it was my go to SG reading throughout the trip for
making therapy decisions; preventing hypos and highs, planning carbohydrate
intake for exercise, and giving corrections etc.
2. When you calibrate
you get an almost instantaneous shift in the SG reading to BG level, which
gives the feel that it is back on track and increased confidence in the SG
reading. This does come with some limitations as discussed below, but I did
really like this, whether it is a Jedi mind trick or not!
3. The receiver and
display is small, the screen is easy to read and rate of glucose change arrows
are easy to interpret. See part 2 for how I used the arrows to optimise control.
My fiancé was most impressed with the leather pouch it came in that folds open,
whilst I was more impressed with the accuracy!
4. It has a G5 APP for both iPhone and Andriod that allows
several devices to be linked to the sensor output. As I am an Apple man this
means I can access the reading on my phone. Not really needed to put on my
mum's phone but if I was 25 years younger this would be invaluable for a bedroom
iPad or iPhone. See Nightscout for
more details on further sharing capabilities.
5. The
G5 uploads to Diasend, which means I can add the data to that of other devices
to get a complete picture of all the variables I need to assess.
The limitations and
potential solutions:
1. The G5 does not
have predictive alarms, and I believe this explains why it can make an
instantaneous shift in SG once calibrated. The G5 seems to prioritise
preventing glucose excursions in the future by getting the SG back on track as
quickly as possible, so the user can make the most effective future decisions.
This is in contrast to the VEO and MM640G that use predictive algorithms which
aim to prevent problems from happening, with predictive alarms and predictive
suspends (SMART GUARD). Due to the predictive algorithms the change in SG once
calibrated is much slower with the VEO and MM640G, but they do have the
potential of preventing hypos more effectively before they happen. For me this
is a question of user preference; are you a person that wants to be in charge
and be very proactive with management? Or a person who would rather the
technology make more of those decisions? As you may have guessed I am the
former, and for that reason I prefer the G5 for that reason. It will be
interesting to see in the future, with technologies moving to close the loop,
if Dexcom incorporates predictive algorithms, or if it stays with the proactive
user, or can it do both?
2. When the G5 loses
transmission with receiver for any length of time and then reconnects, there is
no backfill of data. Therefore the transmitter is purely that, and it is not a
recorder. This is in contrast to the Libre, VEO and MM640G which have about 8
hours worth of recording time. So as long as connection is not lost for more
than 8 hours you get a full picture. This is very important when reviewing data
on download, and could cause a serious issue for water sports people, and
sports people who are out of range from their device for extended periods of
time. Hopefully a future G5 transmitter will also have recording capability.
3. At present the G5
is not compatible with Animas Vibe, only the G4. Therefore the G5 is not at
present available in any integrated insulin pump system, and you would have to
use a receiver or your phone. Carrying around multiple devices is a pain in the
arse, and that is one of my favourite things about the VEO and MM640G, they are
integrated and attached to me, so I always have the CGM to hand and arse! The
quicker the G5 is integrated into the Animas Vibe, and potentially other pump
systems, the better.
4. The insertion of
the sensor is the most tricky of all and is a bit "fiddly". A simpler
insertion would certainly be welcome, but for
me this is a minor issue when you consider the accuracy!
I
must mention that I worked for Medtronic for four years (2011 - 2015) as a
Diabetes Clinical Specialist, and I did a series of blogs called 64 days on the
MM640G about eighteen months ago, which you can look into if you like on
earlier episodes of this blog. I was wearing the MM640G up until January 2016,
but after a review of almost a year's worth of data I found that the sensors
were only lasting 3 days on average, due to getting "Sensor Error"
alerts, because of some issue with the Enlite sensor or new algorithm in the
Guardian Link Transmitter. Therefore I changed back to my trusty VEO, which I
love. That being said it seems this
"Sensor Error" issue may have been sorted with a change in the Enlite
sensor, as I have been informed by Medtronic that a change in the Enlite was
made recently, and during the 14 days I did not get any "Sensor
Error" alerts.
Medtronic informed me after my trip that the Guardian Link Transmitter
has been
updated with a new algorithm that boasts a MARD of 9%. They are sending
me a new
transmitter with a new inserter to trial. Therefore the review in this
blog and below is based
on the Guardian Link Transmitter that reports a 13-14% MARD and it may be
that the new
version changes things. If it does what it says on the tin, I will soon be back on the
MM640G. I will keep you posted because if it does do the trick then if
you have the old
Guardian Link for MM640G, you will certainly want to be upgrading!
What
I loved:
1. It's a fully integrated system so
you only need one device. It is connected to you and it is waterproof.
Therefore there is no need to take it off and you have access to the CGM 24/7!
2. It has 8 hours of data storage
in the Guardian Link Transmitter, so even if the MM640G does lose connection
you get backfill of data.
3. It is easy to see in the night,
so no need to turn on light or screw your eyes to see it. Very useful in a tent
at the bottom of the Grand Canyon!
4. SMARTGUARD during the night!
When the only variable causing glucose drop is basal insulin (e.g. through the
night), suspending the insulin 30 minutes before without alarms is perfect for
preventing hypos and allowing a full night's sleep! This comes with a caveat -
only if the SG reading is accurate enough. The accuracy section showed the
MM640G had the highest number of false low alerts at 4.2mmol/l, which would
have meant a lot of false suspends of insulin if I was wearing it for real. This
is why accuracy is so important, and at a level of 14% MARD, it is
questionable. I did not have SmartGuard working for me during the 14 days as I
was wearing the VEO. In my previous Blog "64 days on MM640G" you can
see lots of times where night time hypos were prevented. However, as mentioned
in the alarms section with 10 false alerts at 4.2mmol/l, what woudl that have
translated into false suspends. If the new Guardian Link Transmitter achieves
9% then Boom Shakalaker. I will
report back when I have road tested it.
The limitations and
potential solutions:
1. SMARTGUARD during the day for me is not useful. Partly because of
the current accuracy of 14% MARD, but mainly because only stopping basal
insulin has no benefit when you add in bolus insulin, activity and food. In
fact it is detrimental as it makes my insulin depleted later leading to rebound
high blood glucose levels. See the download below where I turned SmartGuard on
for one of the days hiking, to simulate what would have happend, remember I was
always attached to the VEO for insulin. The blue markers indicate the basal
would have been off virtually all day which would have lead to a lot of high
glucose reading later. My solution for
me is to only have SMARTGUARD on during the night and off during the day,
which is great as the MM640G has that capability. I really hope the new MARD of
9% comes true for me with the new transmitter, as i believe SmartGuard is a
massive safety enhancer but only at a MARD of 10% of 14%.
2. You can only upload to CareLink
Personal and as a patient you cannot get access to CareLink Pro reports.
Diabetes is a SELF-MANAGEMENT LONG TERM CONDTION where the person with it needs
to be empowered and educated to make all therapy changes. By providing the
person with sub-standard reports this is in opposition to that. You can
probably feel my passion on this subject, and this was the same passion I
shouted from the roof tops when working for Medtronic. So again, please make
the CareLink Pro reports available, or better still join Diasend so all of a
person's devices can be uploaded to one place so that ALL PEOPLE WITH DIABETES
HAVE THE BEST CHANCE OF SELF-MANAGEMENT. Rant over, I do think Medtronic is an
excellent company and is one of the only companies who puts their devices to
the test in Randomised Control Trials that allow re-imbursement to happen.
Whilst other companies ride on the back of this evidence wave to bring their
products to market, but that's capitalism for you!
3. The time it takes for the SG to
catch up with BG after calibration is frustrating. However, as discussed in the
G5 section it is needed so that features such as SMARTGUARD are possible.
What
I loved:
1. Essentially, all the same
things as the MM640G.
2. I have a special place in my
heart for the VEO as it has been literally by my side hugging my bum for the
last 6 years! This is a testament to its quality.
3. It has the option of Low
Glucose Suspend that is very seldom needed for me, as the alarm at 4.2mmol/l
alerts me so I can take action. However, on the day the two days I turned all
alarms off to see If I could manage by Libre alone, I left Low Glucose Suspend
on for back up. The download below is
the night after we had finished the Grand Canyon Trek, I was exhausted
and fell asleep. That night I woke up to Low Glucose Suspend shouting at me. On
review I had been hypo for ages and slept through 90 minutes of insulin
suspension and Low Glucose Suspend alarm with a BG of 2.4mmol/l. Without Low
Glucose Suspend that could have been much lower, and required my newly crowned
fiancé Dani to use her Glucagon training! Secretly I think she would have
enjoyed playing nurse. Low Glucose Suspend and the research evidence behind it
is why the NICE (2016) DAP specifically indicates the VEO for funding for
people with hypoglycameia unawareness issues.
The limitations and
potential solutions:
1. Same as MM640G for CareLink and
accuracy.
2. Although trusty, loyal and my
best friend, it's not the most beautiful pump in the world and the screen can
be tricky to see, especially at 4am! This has been rectified by the MM640G with
the colour screen.
3. I will rank each CGM system on different key areas:
Accuracy for me: MARD, Alarms, safety to bolus from SG
1. G5
2. VEO
3. Libre
4. MM640G *pending trailing the
new Guardian Link with reported 9% MARD
Ease of use for me: Set up, sensor insertion, navigation, looking at graphs,
calibrating
1. Libre
2. All equal: MM640G, VEO, G5
Key Features for safety for me: Alarms, Low Glucose Suspend,
SmartGuard,
1. VEO - only one missed hypo and
saviour of via Low Glucose Suspend on the 15th!
2. MM640G and G5 joint second
a. MM640G - SmartGuard during the
night only for me but questionable with current 14% MARD. I await to see if 9% with new Guardian Link
makes a significant difference for me, then this would put it on top.
b. G5 - no missed hypos with alarm
set at 4.2mmol/l and amazing accuracy
3. Libre - only get safety with
extreme frequent swiping when doing heavy exercise and no protection through
the night.
Key Features for proactive management
for me: Making decisions in
real-time for bolus,
exercise management, hypo prevention:
1. G5 - Accuracy is king for
pro-active management when combined with glucose trend arrows low and high
alerts
2. VEO, MM640G - Hard to
differentiate from Libre on accuracy and glucose trend arrows, but having low
and high alerts prevents obsessive compulsive swiping I needed to stay on top
of things with the Libre
3. Libre - Having no alarms was a
limitation for me.
Cost
I originally wanted to say which I thought was the best value for money,
but this question is completely dependent on the perspective of the user and
their priorities. So in its place I have modelled some cost projection based on
the current cost. These costing are subject to the companies changing prices
and offering start up deals. I have not ventured into use of one sensor a month and other scenarios because the research, my personal
experience, and my work experience all show clearly; for CGM to be of benefit and effective, it must be worn full-time. This is because how you manage your
diabetes on CGM is very different to BG alone, and this takes practice,
practice, practice. The cost models are for:
1. Start up costs for receiver and
transmitter
2. Annual cost of full-time CGM
according to manufacturers specification
3. Annual cost of full-time CGM
according to stretching the sensor usage out to 14 days each. My experience of
them working to specified MARD% after day 7 for G5, VEO and MM640G is not
fantastic, however, I am aware from the online community that some people
report sensors last from 14 - 21 days. So I have included this.
Set up costs for all four CGM devices
Device
|
Receiver
|
Transmitter
|
Total
|
Libre
|
£133
|
0
|
£133
|
G5
|
£275
|
£200
|
£475
|
MM640G
|
Already
have pump
|
£490
Inc.
charger
|
£490
|
VEO
|
Already
have pump
|
£490
Inc.
charger
|
£490
|
Annual cost of CGM according to manufacturers specification
Device
|
Transmitters
|
Sensors
|
Total
|
Libre
|
£0
|
£1,159
|
£1,159
|
G5
|
£800
Each
last 3 months
|
£2,460
|
£3,260
|
MM640G
|
£350
Excluding
charger
|
£2,760
|
£3,110
|
VEO
|
£350
Excluding
charger
|
£2,760
|
£3,110
|
Annual cost of CGM according if can stretch sensor life to 14 days
Transmitter
|
Each
sensor lasting 14 days
|
Total
|
|
Libre
|
£0
|
£1,159
|
£1,159
|
G5
|
£800
Each
last 3 months
|
£1,230
|
£2,030
|
MM640G
|
£350
Excluding
charger
|
£1,380
|
£1,730
|
VEO
|
£350
Excluding
charger
|
£1,380
|
£1,730
|
A quick summary would show there is
very little difference for the G5, VEO, MM640G as the fully alarmed CGM
systems, all at roughly around £3,000 per year. The Libre is only a third of
that price at £1,159 per year but has the limitations of no alarms. I will
discuss who may benefit from which more in the final section.
If you are interested in just dipping
your toe into the CGM field it would seem sensible to try with the Libre as it
is the cheapest start up, easiest to use, will not annoy you with alarms and
lasts the longest. However, if you want to manage your diabetes more
pro-actively or suffer from problematic hypoglycaemia issues, you may well
choose an alarmed system instead.
On a note to the companies! What
would make this much more accessible would be bringing down the cost, which I know goes hand in hand with increased usage and therefore reduced manufacturing
costs! But do not forget, I used to work for one of the big companies and know
how much profit they make, even though Medtronic certainly does pump a lot of
money back into research and development. Some initial concessions that would
help:
·
Dexcom to reduce the cost of the transmitter. They only last three
months and cost £200 each. If you have made a device with such a short battery
life, that cost should be born by you, as the user/NHS bears the cost of each
sensor. A reduction to £100 would be a generous saving of £400 per year,
effectively two free months of CGM!
·
Medtronic could reduce the cost of the transmitter, which has 1 year
warranty and cost of £350. If they only cost £150 then a saving of £200
would be a free month of CGM for the user/NHS who bears the cost of each
sensor.
·
If fairness Abbott have done a good job with this and that is part of
their marketing appeal.
4. My thoughts on the groups of
people who may benefit the most from different systems.
The final
section, Whoop Whoop!
IMPORTANT, what to come is my
opinion only! If you fit into these categories it does not mean the NHS or your health
care provider will fund it for you, and your Health Care Team may not even be
interested. It may provide you with some information to have a discussion with
your team and it may even persuade you to pay for it yourself. Again, question
everything I write with a critical eye and make your own mind up. I have put
the type of person I think would benefit the most for each device. After that I
briefly discuss the NHS guidance for the U.K readers to help understand the
funding jungle!
Libre - Who I think would
benefit most
1. People interested in CGM but
still not convinced and want to dip their toe to see if it will benefit them.
2. People who want to
significantly reduce the number of finger pricks but are not as interested in full-time proactive
management of diabetes
3. Parents who want to be able to
see what happens during the night with a swipe, rather than waking their
children
4. People who just want diabetes
to be a bit easier without information and alarm overload
5. People who have budget constraints.
Some parents receive DLA (Disability Living Allowance) money and this could be used to
reduce the burden of diabetes. Do not start shouting at me here, I can feel the
daggers in my back, it is only an option.
G5 - Who I think would benefit
most
1. People who want to pro-actively
manage their diabetes with the most accurate information e.g. sports people,
high flyers & achievers, engaged and educated parents, and the planners of
this world.
2. People with issues of
hypoglycaemia that respond to alarms or their parents respond to alarms
3. People who want to spend time
learning about how to adapt new strategies according to CGM output and alarms
4. Ideal for people on MDI who do
not want a pump or an integrated pump system
5. People who do not mind carrying
two devices if they are on a pump. This is until the G5 becomes available in
some pumps
MM640G - Who I think would
benefit most
1. People who want their device to
take away some of the decisions and relieve some of the decision fatigue of
diabetes
2. People with issues of
hypoglycaemia that do not respond to alarms or their parents do not respond to
alarms
3. People who are thinking of
going onto a pump and want an all-in-one integrated system and obviously those
already on the MM640G
4. People who want to move closer
to closing the loop. As advances in transmitter CGM algorithms will happen over
the four years, you would have a pump that will access some of these
VEO - Who I think would benefit
most
1. People who want their device to
take away some of the decisions and relieve some of the decision fatigue of
diabetes
2. People with issues of
hypoglycaemia that do not respond to alarms or their parents do not respond to
alarms
3. People who are thinking of
going onto a pump and do not have access to the MM640G and want an all in one
integrated system, and obviously those already on the VEO
4. People who love the tried and
tested with solid research evidence proving Low Glucose Suspend
What NHS
Guidance is there and how may it help?
There are
a few key NICE guidance documents that will help in your quest to obtain
funding from the NHS. This is a brief summary of my understanding but
please go to INPUT for much more
objective analysis and guidance documents/templates that will really help!
Continuous glucose monitoring
1.6.21 Do not offer real‑time
continuous glucose monitoring routinely to adults with type 1 diabetes. [new
2015]
1.6.22 Consider real‑time
continuous glucose monitoring for adults with type 1 diabetes who are
willing to commit to using it at least 70% of the time and to calibrate it as
needed, and who have any of the following despite optimised use of insulin
therapy and conventional blood glucose monitoring:
·
More than 1 episode a year of severe hypoglycaemia with no
obviously preventable precipitating cause.
·
Complete loss of awareness of hypoglycaemia.
·
Frequent (more than 2 episodes a week) asymptomatic hypoglycaemia
that is causing problems with daily activities.
·
Extreme fear of hypoglycaemia.
·
Hyperglycaemia (HbA1c level of 75 mmol/mol [9%] or higher) that
persists despite testing at least 10 times a day (see
recommendations 1.6.11 and 1.6.12). Continue real‑time continuous glucose
monitoring only if HbA1c can be sustained at or below 53 mmol/mol (7%)
and/or there has been a fall in HbA1c of 27 mmol/mol (2.5%) or more. [new
2015]
1.6.23 For adults with type 1
diabetes who are having real‑time continuous glucose monitoring, use the
principles of flexible insulin therapy with either a multiple daily injection
insulin regimen or continuous subcutaneous insulin infusion (CSII or insulin
pump) therapy. [new 2015]
1.6.24 Real-time continuous
glucose monitoring should be provided by a centre with expertise in its use, as
part of strategies to optimise a person's HbA1c levels and reduce the frequency
of hypoglycaemic episodes.[new 2015]
My
opinion: A lot of people meet these criteria and would really benefit from
full-time CGM. However, this NICE guidance does not mandate the commissioners
to pay for it, it is merely guidance. Their decision to fund will be based solely
on the strength of the individual funding request submitted by the health care
team looking after the person with type 1. Therefore if you believe you meet
the criteria, need it, and deserve it; you owe it to yourself to make your
health care team believe also! That is what I did! But please remember your health care team do not make the decision, they work with you to submit the
request, they will be working with you if they believe!
1.2.62 Offer
ongoing real-time continuous glucose monitoring with alarms to children and
young people with type 1 diabetes who have:
·
frequent severe hypoglycaemia or
·
impaired awareness of hypoglycaemia associated with adverse consequences
(for example, seizures or anxiety) or
·
inability to recognise, or communicate about, symptoms of hypoglycaemia
(for example, because of cognitive or neurological disabilities). [new 2015]
1.2.63 Consider
ongoing real-time continuous glucose monitoring for:
·
neonates, infants and pre-school children
·
children and young people who undertake high levels of physical activity
(for example, sport at a regional, national or international level)
·
children and young people who have comorbidities (for example anorexia
nervosa) or who are receiving treatments (for example corticosteroids) that can make blood glucose control difficult. [new 2015]
1.2.64 Consider
intermittent (real-time or retrospective) continuous glucose
monitoring to help improve blood glucose control in children and young
people who continue to have hyperglycaemia despite insulin adjustment and
additional support. [new 2015]
My opinion: A lot of children and young people meet these criteria and would really benefit from full-time CGM. However, this NICE guidance does not mandate the commissioners to pay for it, it is merely guidance. Their decision to fund will be based solely on the strength of the individual funding request submitted by the health care team looking after the person with type 1. This is slightly different if you are on an integrated pump with sensor (see below). Therefore if you believe you meet the criteria, need it, and deserve it; you owe it to yourself to make your health care team believe also! But please remember your health care team (this is me) do not make the decision, they work with you to submit the request, they will be working with you if they believe!
3. NICE
(2016) DG21 on integrated sensor
augmented pumps- For Children
and Young People only - those 18yrs or under
“MiniMed Paradigm Veo system is recommended
as an option for managing blood glucose levels in people with type 1 diabetes
only if they have disabling hypoglycaemia”
“The Vibe and G4 PLATINUM CGM system shows
promise but there is currently
insufficient evidence to support its routine
adoption in the NHS for managing
blood glucose levels in people with type 1
diabetes”
“MiniMed 640G system has not been assessed
in the guidance, and the recommendations, therefore, do not relate to its
routine use in the NHS”
My
opinion: A lot of children and young people are already on a VEO that meet
these criteria, and there should is a direct line of funding from NHS England.
So if you believe, get asking. If you are on a MM640G or Animas Vibe you may be
able to slip under the radar and hopefully future evidence will extend to
these.
Children
and young people with type 1 diabetes who have frequent severe
hypoglycaemia are offered ongoing real‑time continuous glucose monitoring with
alarms.
My
opinion: This is a bit of a game changer for children 18 years or under. For
the first time it is recognised that MDI patients should not have to go on a
pump to get the benefit of alarmed CGM. If given a choice of losing the pump or
CGM, I would lose the pump and stay on CGM with MDI. I believe the information
and lifestyle management possible with CGM outweighs the advantage of a pump.
Put the two together BOOM, but if a choice, CGM for me. There is no direct line
of funding for this at present and each patient will have to go through an
individual funding request, unless your centre has already got an arrangement
in place for a pot of money. Either way you have to believe and then make your
health care team believe you need and deserve it.
On a
side note, Abbott have put a request into the NHS to get the Libre onto FP10 for
prescription. If this gets passed it means your G.P. will be able to prescribe
it which would be a huge game changer! Watch this space!
Final comments
If you
have made it this far then I hope it has been a worthwhile investment of your
time (just imagine how much time I invested!). I believe CGM is the next big
step forward for the majority of people with diabetes, not just those who can
afford it, or the small niche who are currently benefiting from the NHS or self-funding. As with anything in
life there is no 'one size fits all', it is horses for courses, and I hope this
blog has helped you select the best noble steed for you.
I am
going to write a blog over the next month (these things take serious time and I now have a wedding to plan!) on
how I manage my diabetes with CGM using my USA experience as the case study. It
will include:
·
How I use
the trend arrows to plan for exercise
·
How I
change bolus amounts based on trend arrows
·
How I
prevent night time hypos with CGM
·
How I
managed a 4 day trek with diabetes exercise management strategies
·
My
life and diabetes philosophy and how stoicism and a growth mindset is my key to
controlling Diabetes
·
Details
on my trip:
o
Getting
engaged in the Grand Canyon
o
Getting
a ring together in the famous Pawn Starts shop in Vegas
o
Dancing
at the front of MJ Cirque Du Soliel
o
How
amazing the Wildland Trekking Company is, especially our guide Ken Parker
·
And
much more
If you
have found it useful please share with those who would benefit. Feel free to
comment but do not expect a reply instantly from me. You will be better
emailing me at jspfree2@gmail.com if you want to know something specific. If
you think I made the results up and want the excel spreadsheets your more than
welcome to them, just email me.
Cheers
John
