
Tracking Blood Sugar - troydavis
https://eric.jain.name/2018/11/25/tracking-blood-sugar/
======
lucas_membrane
I've been using one of these for about 6 weeks, and I find it is not very
accurate, but the convenience that allows checking the readings very often
nearly makes up for the huge error bars. The libre freestyle 14-day is usually
within 15 mg/dl when the reading is between 80 and 100, but above that range,
it is usually off by 20 to 30 percent of the correct value (not 20-30 mg/dl)
and mine has never read much higher than the finger-stick test, only lower.
The lower numbers make me inclined to believe it, but they are simply not
true, the meter gives only about one significant digit of accuracy throughout
its range, and it is pretty far off or refuses to produce a reading when my
blood sugar goes below 60 mg/dl. Still, being able to see at a glance whether
one is 100 or 200 is quite useful. Medicare pays about $500/month for the
attachable sensors, which are extremely convenient and non-problematic so far.

There is a far better wearable system ready to go but not in production, a
combined sensor and automated insulin dispenser, that has passed human trials,
but no one wants to go into production with it because of liability issues.
Given that people are riding in self-driving cars and landing in aircraft on
autopilot, each of which are also potentially fatal and involve a larger set
of variables, I wonder if and how long it will take to progress in this
regard.

~~~
pimeys
The libre is meant for monitoring the trend of the glucose, used together with
a fingerstick reader. You can calibrate the values if you use xDrip to get
better accuracy.

If you're interested in using a closed loop, take a look into AndroidAPS or
Loop, how to build one by yourself. It's all open source and works really
well. Been a user for some years now. You just need to compile it by yourself
and own the right hardware.

~~~
lucas_membrane
> The libre is meant for monitoring the trend of the glucose, used together
> with a fingerstick reader.

Then it gets to be an issue with cost and convenience, as hauling around both
systems with lancet device and strips and insulin and syringes and glucose
tablets is a nuisance for anyone who does not carry a purse. Test strips cost
around a dollar each (if one eschews the likes of Walmart), and it is very
difficult to get Medicare to pay for more than 3 per day. I do not know if
they will pay for any now that they are paying the higher monthly cost of the
libre sensors.

------
troydavis
Here's a second non-diabetic who tracks their glucose with the same non-
invasive device and started analyzing it.

Blog post:
[https://richardsprague.com/notes/cgm/cgm_analysis/](https://richardsprague.com/notes/cgm/cgm_analysis/)

Slides from presentation last week:
[https://www.slideshare.net/richardsprague/quantified-self-
se...](https://www.slideshare.net/richardsprague/quantified-self-seattle-
january-2019-continuous-glucose-monitoring)

He also tweets about it:
[https://twitter.com/sprague](https://twitter.com/sprague)

~~~
gwern
It seems to still be invasive:
[https://www.freestylelibre.us/support/faq.html#faqTabstab-3](https://www.freestylelibre.us/support/faq.html#faqTabstab-3)

> The sensor is applied to the back of the upper arm with a simple, disposable
> device called an applicator. When the sensor is applied, a small (5mm)
> filament is inserted just under the skin, and held in place with a small
> adhesive pad.

'Inserted just under the skin' means it's still invasive, but that sounds
nicer than regular needle-sticks so perhaps 'less-invasive' would be a more
accurate description.

~~~
troydavis
Per the people I know who have tried it, including the author of this post,
it's totally painless. One can debate whether or not a filament you can't feel
is invasive, but for all practical purposes it's the same as no filament.

For clarity: the measurement you pasted is the length of the filament. The
width/thickness is ridiculously tiny. Basically, this product has the same UX
as a nicotine patch.

~~~
Engineering-MD
From a design perspective definitely invasive. Design strategies and
regulations change greatly for products which penetrate the skin. But you are
correct in that it is a patient friendly device without the associated burden
of lost invasive devices.

~~~
SpikeDad
From an FDA perspective invasive also. Otherwise you wouldn't need a
prescription.

------
uncleberg
I wear a FreeStyle Libre every day, AMA. It's very good for T1s, of course.

It's reliable enough - the biggest downfall is that it's around 15 minutes
behind real-time, ie, what you can measure with blood. Sometimes it can feel
'stuck' too, and change rapidly between a short amount of time.

The second model, which I am waiting to try, includes Bluetooth alerts if a
trend high or low is detected. This may make it even more useful.

~~~
westoncb
What do you mean by 'second model'? Like a new version of the FreeStyle Libre?

I just got my first CGM, FreeStyle Libre 14 day, 2 days ago :) The relief I've
already experienced from not having anxiety about where my blood sugar is at
has been incredible. That said, being able to set alerts for lows/highs and
not having to manually scan the sensor would be huge improvements.

The way I was checking blood sugar before (finger pricks) it seemed like I'd
gain relatively little by using a pump, but now I'm thinking a pump may be
indispensable if used in combination with a CGM: Since I can now see how my
blood sugar is changing in near real-time, if I have errors in dose size, I'm
going to want to be able to make small correction...

~~~
uncleberg
Yes, v2 is coming soon or is now out :)

------
mrfusion
Are there any devices that track insulin levels directly?

That’s what I’d be most interested in. Folks conjecture that it’s your insulin
response that causes weight gain rather than the blood sugar increase. They’re
not as correlated as you’d expect!

Source
[https://www.google.com/amp/s/optimisingnutrition.com/2015/05...](https://www.google.com/amp/s/optimisingnutrition.com/2015/05/03/glycemic-
index-load-versus-insulin-load/amp/)

~~~
beardface
Summary: I have no citation but my understanding is that measuring insulin
levels needs to be done from a blood draw, so a Freestyle Libre-type device
wouldn't work.

The Freestyle Libre and regular continuous glucose monitors measure glucose in
the interstitial fluid under the skin - not blood. This is why the numbers can
be wildly different to a blood glucose test done via finger-prick.

From what I've seen while researching very low carb diets, insulin levels are
incredibly important and influence a lot of body chemistry. For example,
someone without type 1 diabetes can have a normal blood glucose but only
because they're producing an enormous amount of insulin. A large amount of
insulin in the blood will cause fat to be stored, so the patient puts on
weight.

~~~
atomical
Your example is someone without diabetes but referred to as a patient?

~~~
beardface
My comment wasn't clear; apologies. I was referring to someone who had blood
drawn to test for and diagnose high insulin levels. I'd classify anyone having
that test in a clinical setting to be a patient.

------
jwr
The Freestyle Libre requires a prescription (why?) — is there another similar
system that does not?

~~~
troydavis
No. In the US, all similar products require a prescription. This is by far the
best available option (no fingerstick calibration, longest-lasting sensor,
easy mobile app, etc.). Basically, get this one. It’s $80 including 1 month of
sensors.

I believe the thinking is that people need a professional to discuss results
with. I understand that perspective, but I don’t agree with it, and I
definitely don’t agree that having someone to discuss results with should
outweigh the increased access/adoption of over-the-counter sales. This is the
first product that makes it practical - even easy - and completely painless
for non-diabetics like me to track blood glucose informationally, so perhaps
this will change. That said, the FDA has made other overly-conservative
decisions, like disallowing fingerstick A1c tests (which don’t require fasting
or a full venous blood draw) for first-pass screening of diabetes:
[http://www.onsitehealthdiagnostics.com/blog/a1c/](http://www.onsitehealthdiagnostics.com/blog/a1c/),
[https://twitter.com/troyd/status/1018150306125758465](https://twitter.com/troyd/status/1018150306125758465).

~~~
jwr
Thanks for clarifying.

As a side note, I think this requirement is completely bogus. You should be
able to get any "read-only" medical device you want, anytime you want,
especially in a country where there is no universal healthcare. I see a
contradiction where on one hand the authorities say: we have to protect you so
that you don't harm yourself and on the other the same authorities say: your
health is your responsibility and we want nothing to do with it.

~~~
SpikeDad
You need a prescription because it's a continuously attached invasive medical
device. You don't need prescriptions for finger stick devices so that's the
only difference between them.

------
Vekz
I enjoyed the Authors blog post history of:

Tracking Blood Pressure

Tracking Blood Sugar

Chocolate Popcorn

Panna Cotta

~~~
guiambros
Plus Smoothies and Protein Shakes. There's clearly a pattern here :)

------
ng12
> The sensors worked as advertised

I mean... yes. They're a prescription medical device used by Type 1 diabetics
to stay alive.

~~~
westoncb
Unfortunately this means less than you'd think. See other comments on this
thread on the subject of accuracy. Also, from my understanding, the current
(still wanting) state of accuracy is the result of large improvements during
just the past few years. Prior to that, CGMs were still prescription medical
devices used by Type 1 diabetics to say alive.

And more unfortunately, it has been my experience that information about
managing blood sugar given to diabetics by doctors is almost uniformly quite
bad (I've received the same sort of overly simplistic, misguided instructions
from 4 or 5 different doctors myself; now I just nod and let them finish
speaking). As a result, nearly every other (non-engineer/scientist) diabetic
I've been met has very bad numbers (A1C: three month average blood glucose)—as
I would have too were I to follow my doctors' advice. Instead I have very good
numbers which are a result of research and reasoning I had to do myself.

~~~
ng12
That's troubling. Which doctors have you been speaking to? I've always gone to
see endocrinologists specializing in diabetes and have never had a doctor give
me overtly bad advice.

~~~
westoncb
Always general practitioners. I tend to just visit them when I need a
prescription now. I haven’t visited an endo since I never understood the
purpose: I suppose they are more expensive and I can just use the internet. My
A1c is generally high threes, so I’m not sure what else they could offer. I’ve
asked general practitioners and they have never been more concrete than:
endocrinologists can help you figure out which pump is right for you. But,
internet.

Edit! High fives, not threes. See my comment below.

~~~
chucknelson
Wow - if you're Type 1 and have an A1C in the "high threes"...you're
definitely one of those exceptional patients. Your A1C is probably better than
some non-diabetics!

I could see why you have a pretty high threshold for the quality of advice you
want. Not sure it's a typical experience, though.

~~~
ng12
It seems dangerous to me. One unit of insulin too much and you're in diabetic
coma territory.

------
SpikeDad
I'm curious about this. Theoretically healthy people shouldn't care about
their blood sugar since your body normally regulates your blood glucose using
insulin and other hormones.

If you're wondering if you may be pre-diabetic then wouldn't an A1C test (home
tests available and are very accurate) be a better diagnostic test?

~~~
DavideNL
That way you can detect a problem, yes.

But HBA1C can sometimes still be good, even for people who have high & low
glucose peaks.

Maybe because the average value will still be good if you have equal peaks
"up" as "down"? i don't know..

------
arihant
It is absurd that two (not one) doctor's scripts are needed to buy a sugar
testing device. I've been trying to get this for my mother but it has been an
awful experience in terms of their willingness to sell. I wish a company that
actually wants to make money would soon offer an alternative.

They are opaque on pricing, do not answer questions about where to buy, do not
clearly state what kind of prescription they need.

------
bbrian
My mother had the Freestyle Libre and liked it. Now using a Dexcom which works
with her Apple Watch. I just bought her a Dario finger-stick glucose meter for
her birthday which plugs into iPhone lightning port ($40!).

[https://imgur.com/a/24FhAON](https://imgur.com/a/24FhAON)

[http://intro.mydario.com/DarioGlucoseMeter/about.php](http://intro.mydario.com/DarioGlucoseMeter/about.php)

------
FabianBeiner
There is a German company offering personalized food recommendation based on
measuring blood sugar:
[https://www.millionfriends.de/](https://www.millionfriends.de/) (Google
Translate:
[https://translate.google.com/translate?sl=de&tl=en&u=https%3...](https://translate.google.com/translate?sl=de&tl=en&u=https%3A%2F%2Fwww.millionfriends.de%2F)).

------
bdcravens
I have the Medtronic MiniMed pump, which includes its sensor that the pump
uses for automated basal dosing. Accuracy is similar to what others have
described.

~~~
dboy1612
How well does the automated bits work? I've considered a pump in the past for
that reason, but was always afraid what mistakes could happen.

~~~
pimeys
If you want to get even better system using AndroidAPS, get the DanaRS pump,
which is the only manufacturer allowing unofficial use.

Before you must do some reading and understand the concepts. OpenAPS and
AndroidAPS are state of the art systems and you can do even better than the
basal setup using the oref1 SMB algorithm. I know countless of diabetics using
it and we all have much better and easier control in our therapy.

[https://openaps.org/](https://openaps.org/)
[https://github.com/MilosKozak/AndroidAPS](https://github.com/MilosKozak/AndroidAPS)

------
fareesh
When I lived in Canada I used to occasionally see infomercials about blood
sugar monitors that didn't require pricking fingers - are those considered to
be any good or is it some kind of infomercial scam? If they are considered to
be mostly accurate, why can't that technology be used instead of having a 5mm
needle in your body, which probably feels uncomfortable, particularly for the
elderly.

~~~
SpikeDad
Monitors that don't need a finger stick can take blood from other body areas,
usually the forearm. The theory is there are less nerves in places other than
the finger.

The result is not considered as accurate compared to finger sticks but it's an
option for people that can't really stick their fingers I guess.

They're mostly the more modern ones that don't need much blood. Also the ones
I've purchased have a special attachment for the lancet device to accommodate
the different location.

The ads do seem to imply that you don't need to use a lancet but that's just
marketing and advertising. You still need to use a lancet to get a drop of
blood.

------
mrfusion
I tested my blood sugar with strips for a few days. One wierd thing I noticed
for some meals is I’d be at 98 blood sugar or so before the meal but within 30
minutes after a moderate meal I’d be at 78 or so. Seemed really backwards.

~~~
pjc50
Digestion uses a surprising amount of energy, this is why people tend to feel
sleepy after carb-heavy meals. And diabetics need to plan carefully.

~~~
slacka
>why people tend to feel sleepy after carb-heavy meals.

No. This is well understood science. The fatigue you feel soon after eating is
caused by postprandial hyperglycemia, or a “spike” in blood sugar soon after
eating.[1] You can, and I have tested this after overeating carb heavy meals
and that's exactly what's going on.

I'm prediabetic, so I watch this carefully as I have a family history of
diabetes.

[1] [https://www.diabetesselfmanagement.com/nutrition-
exercise/nu...](https://www.diabetesselfmanagement.com/nutrition-
exercise/nutrition/tired-hungry-after-eating-diabetes-questions-answers/)

------
ouid
I know someone who could benefit (either psychologically or medically) from a
sort of holter monitor for her blood glucose levels. Are you the person who
wrote this? If so how did you get your prescription?

~~~
troydavis
I’m not the author, but the author simply asked their primary care doctor for
one and I know others who have done the same. Next time you’re at the doctor,
just explain that you want to be proactive about health and ask for one.

Make sure to get the 14-day version: [https://www.freestylelibre.us/system-
overview/freestyle-14-d...](https://www.freestylelibre.us/system-
overview/freestyle-14-day.html). It’s about $80 (cash to a pharmacy, not
through insurance) and includes 2 14-day patches.

Over the next year or two, performing at least a few weeks of real-time
monitoring per year will become standard practice among those who consciously
monitor their health. With the Libre, doing a few weeks per year is no harder,
and not much more expensive than a home blood pressure cuff. It’s not even all
that expensive to do year-round.

(I don’t think this should require a prescription, but in the US it currently
does.)

~~~
atomical
It's a waste of money and time for the average person that eats right and
exercises. It borders on obsessional behavior.

------
atomical
> Fasting glucose and A1C tests done over the past few years show me at low
> risk for diabetes. But these tests don’t necessarily capture how much blood
> sugar “spikes” after meals–something that may be a better predictor of
> disease risk.

It's hard to take the author's concern seriously when he is at low risk. A
better take is that he's just curious.

------
thisisnotmyname
I'd be curious to know how he measures stress levels.

~~~
ejain
I don't even know how I'd go about measuring stress levels, but I did notice
that there were two instances where my blood sugar staid elevated for much
longer than it should have after lunch, and both times there was a somewhat
stressful/non-routine situation (an interview, and riding a scooter across
town).

------
jogundas
What about availability of this outside the US?

