Huge Difference Between Labs and Home Meter

[MattInUSA]

Hey Folks,

I'm from the USA, but I like the looks of this forum, so hopefully I'll do my conversions correctly. In 2015, I started testing my blood glucose at home because my A1C was borderline prediabetes despite being very lean. I used as many as three different meters, and was getting post-prandial readings of 10+ mmol with only a potato and some beans being the carbs. I started walking after meals and managed to take my A1C from 6.3 mmol to 5.2 mmol. My fasting glucose and insulin looked fine (HOMA under 1), doctors refused other tests including antibodies, so I let the issue drop.

Move forward to a few months ago, and I have a brain surgery coming up. I did keto for a little while to see if it would improve my symptoms, but I just felt weak and tired. I went back to carbs, and for some reason found the urge to start testing again (with new strips of course). I've been using a ReliOn Prime and Easy Max V. My readings are again 10+ mmol after meals, sometimes exceeding 11. Panic again that I'm becoming diabetic before my surgery. This time I knew how to pay for my own labs, so I purchased an A1C, OGTT (including fasting insulin and glucose, plus insulin and glucose at 1 and 2 hours), and diabetic antibodies (for which I'm awaiting the results). When I went for the OGTT, I used my own meter to do finger sticks in my car just before going in to get drawn. There's...a bit of a discrepancy.

My Meter / Lab Draw
Fasting Glucose (in mmol/L) 4.8 / 4.6
30 minutes Glucose 11.4 / *
1-hour Glucose 10.9 / 7.4
1.5-hour Glucose 10.1 / *
2-hour Glucose 7.2 / 3.4
3-hour Glucose 3.1 / *

Other tests:
A1C - 5.4 mmol/L

Insulin Fasting - 3.9 uIU/mL
Insulin 1-hour - 32.9 uIU/mL
Insulin 2-hour - 17 uIU/mL

So the fasting measurement is in agreement, which is pretty much what I found in 2015. However, the post-prandial readings are massively different. The two hour reading in particular is more than twice as high via finger stick compared to the lab draw. Can anyone explain this? The lab readings are more in line with the A1C I've been given, which if accurate means the home meters are significantly out of range once numbers start going up, far more than the 15% that that's required. Now I really don't know what to trust. I'm also not sure what those insulin numbers mean since they didn't give any point of comparison, but a little research shows they look on the low side (could be insulin sensitive or pancreas could be failing).

Any thoughts are appreciated.

 

[Ronancastled]

There can be noted differences between capillary readings & venous lab draws but I would still question your meter(s).
Drop into your local pharmacy & ask them to test you on their own model which they will.
Control solutions have too wide a range & are useless.

On the subject of your 2hr 75g OGTT your results look perfect.
I've attached a completely normal result below for your comparison.

This baseline was established by an American practitioner called Kraft who rans 1,000's of these to identify normal.
Your 2 hour result is a touch hypo but as you were eating lower carb before the test you probably over produced insulin around the 90 min mark as your system was shocked.

I think you're fine but would probably question your strips.

 

[MattInUSA]

Thanks for the response and the useful chart. I was actually consuming carbs for over a month before the OGTT (I ended the low carb experiment in April), so I'm not sure why I went hypo except that I typically have salad and meat with my carbs, not a straight-up glucose bomb like the OGTT. Not sure I'll do that test again, I felt really crummy for the entire day. I also wish I had a 30 minute insulin reading, but couldn't find that when searching through the available tests. My antibody results came back below the positive threshold as well, so I guess I have to accept that I'm not diabetic and that my meters are really, really inaccurate. I still don't understand how they're THAT far off, they're supposed to be within 15% and the difference was 100% at the two hour mark. I'm not sure our pharmacies do glucose tests in the states, but I'll ask.

BTW, congratulations on the weight loss and insulin sensitization. I don't think it's terribly uncommon to have a normal A1C via low carb, but to pass the glucose tolerance test as well is a significant achievement.

 

[AndBreathe]

Thanks for the response and the useful chart. I was actually consuming carbs for over a month before the OGTT (I ended the low carb experiment in April), so I'm not sure why I went hypo except that I typically have salad and meat with my carbs, not a straight-up glucose bomb like the OGTT. Not sure I'll do that test again, I felt really crummy for the entire day. I also wish I had a 30 minute insulin reading, but couldn't find that when searching through the available tests. My antibody results came back below the positive threshold as well, so I guess I have to accept that I'm not diabetic and that my meters are really, really inaccurate. I still don't understand how they're THAT far off, they're supposed to be within 15% and the difference was 100% at the two hour mark. I'm not sure our pharmacies do glucose tests in the states, but I'll ask.

BTW, congratulations on the weight loss and insulin sensitization. I don't think it's terribly uncommon to have a normal A1C via low carb, but to pass the glucose tolerance test as well is a significant achievement.

Going back to your OGTT fingerprick tests; are yiour strips in date? If they are/were out of date, that can have lead to erroneous readings.

 

[MattInUSA]

Going back to your OGTT fingerprick tests; are yiour strips in date? If they are/were out of date, that can have lead to erroneous readings.

Not only are they in date, I bought a new bottle and am still getting erroneous readings. Maybe the meter is to blame because other meters are proving to be consistently 2 mmol/L lower post-prandially. They all basically match when fasting. Whatever the reason, I feel a lot better in ketosis compared to eating carbs.

 

[AndBreathe]

Not only are they in date, I bought a new bottle and am still getting erroneous readings. Maybe the meter is to blame because other meters are proving to be consistently 2 mmol/L lower post-prandially. They all basically match when fasting. Whatever the reason, I feel a lot better in ketosis compared to eating carbs.

OK. Some time ago, I had a batch of strips that were all "off". My supplier replaced them, based on my feedback, that of others and their own research/testing.
Do you have a control solution for that meter? That could help you get to the bottom of it all.

Do you have diabetes? If so, which type? If not, what is your interest in diabetes?

(I'm good on questions. I ask a lot. )

 

[MattInUSA]

OK. Some time ago, I had a batch of strips that were all "off". My supplier replaced them, based on my feedback, that of others and their own research/testing.
Do you have a control solution for that meter? That could help you get to the bottom of it all.

Do you have diabetes? If so, which type? If not, what is your interest in diabetes?

(I'm good on questions. I ask a lot. )

I previously had a control solution and it was pretty accurate. It's the post-prandial numbers (aka elevated glucose) that are really askew so I'm not sure a control solution would show the extent of the problem. I actually did call the company and they responded, but I don't really care to deal with it (brain tumor is taking more of my attention). I've suspected I'm a soon-to-be LADA for the last ten years. Not so soon I guess, my A1C has skirted with pre-diabetes that entire time, but walking after meals reliably lowers it and the doctors in the states just aren't interested until fasting numbers or A1C are really deranged. I recently found out about self-paid testing so I decided to check if I have insulin antibodies and how I'd respond to the OGTT. I just don't feel great eating carbohydrates, and the standard advice to lose weight doesn't really apply to someone with a BMI of 19 (and I eat far beyond my supposed caloric needs). To top it all off, I have the brain tumor, and supposedly lifestyle isn't a factor, but it's hard not to wonder if poor glucose control hasn't contributed and what may have happened if I'd just gone low-carbohydrate 10 years ago. I also have a strong family history of diabetes, including a father and aunt with it, and another aunt who died from its complications, so I'm very cognizant of the negative effects it can have.

 

[HSSS]

I previously had a control solution and it was pretty accurate. It's the post-prandial numbers (aka elevated glucose) that are really askew so I'm not sure a control solution would show the extent of the problem. I actually did call the company and they responded, but I don't really care to deal with it (brain tumor is taking more of my attention). I've suspected I'm a soon-to-be LADA for the last ten years. Not so soon I guess, my A1C has skirted with pre-diabetes that entire time, but walking after meals reliably lowers it and the doctors in the states just aren't interested until fasting numbers or A1C are really deranged. I recently found out about self-paid testing so I decided to check if I have insulin antibodies and how I'd respond to the OGTT. I just don't feel great eating carbohydrates, and the standard advice to lose weight doesn't really apply to someone with a BMI of 19 (and I eat far beyond my supposed caloric needs). To top it all off, I have the brain tumor, and supposedly lifestyle isn't a factor, but it's hard not to wonder if poor glucose control hasn't contributed and what may have happened if I'd just gone low-carbohydrate 10 years ago. I also have a strong family history of diabetes, including a father and aunt with it, and another aunt who died from its complications, so I'm very cognizant of the negative effects it can have.

There are other types than 1 (including LADA) and 2. Various MODY ones that are strongly genetic for example. I know little about those but it might be worth a bit of digging into them to see if anything rings any bells for you

 

[AndBreathe]

I previously had a control solution and it was pretty accurate. It's the post-prandial numbers (aka elevated glucose) that are really askew so I'm not sure a control solution would show the extent of the problem. I actually did call the company and they responded, but I don't really care to deal with it (brain tumor is taking more of my attention). I've suspected I'm a soon-to-be LADA for the last ten years. Not so soon I guess, my A1C has skirted with pre-diabetes that entire time, but walking after meals reliably lowers it and the doctors in the states just aren't interested until fasting numbers or A1C are really deranged. I recently found out about self-paid testing so I decided to check if I have insulin antibodies and how I'd respond to the OGTT. I just don't feel great eating carbohydrates, and the standard advice to lose weight doesn't really apply to someone with a BMI of 19 (and I eat far beyond my supposed caloric needs). To top it all off, I have the brain tumor, and supposedly lifestyle isn't a factor, but it's hard not to wonder if poor glucose control hasn't contributed and what may have happened if I'd just gone low-carbohydrate 10 years ago. I also have a strong family history of diabetes, including a father and aunt with it, and another aunt who died from its complications, so I'm very cognizant of the negative effects it can have.

I'm sorry you are having to handle a brain tumour. I wish you the best with it.

In terms of LADA, my Endo (whom I see for my errant thyroid) thinks I may be LADA and advises I keep an eye on my numbers. Several years down the line, on a reduced carb way of eating my A1c meanders between 30 and 34, with a low of 29, so he is dumbfounded each time we meet. On that basis, I think predictions are worthless.
Depending on your metabolism, diet and lifestyle (and a few other things), your caloric requirements will vary. On a textbook basis, I am petite and compact, consuming calories far in excess of the predicted requirements for my under 50kg body. I consume many hundreds more calories per day.

I think there are times to look inwardly and try to work stuff out, and there are times to accept that the steady state is just that, and get on with other things.

If you feel well on a ketogenic diet, and your general health (notwithstanding your brain tumour) is good, then I would urge you to enjoy your life, and live it well.


(In the interests of full disclosure, were I ever diagnosed with a cancer, I would be doubling down on reducing my carbohydrate intake, but thankfully, for now, that is not a challenge I believe I need to address.)

 

[MattInUSA]

There are other types than 1 (including LADA) and 2. Various MODY ones that are strongly genetic for example. I know little about those but it might be worth a bit of digging into them to see if anything rings any bells for you

Thank you. MODY was my other suspicion back when I was trying to get help, but doctors refused testing for anything because my A1C was just out of the pre-diabetes range. I'd kind of forgotten about it, but I just looked and there are some more tests available if I want to go that route.

In terms of LADA, my Endo (whom I see for my errant thyroid) thinks I may be LADA and advises I keep an eye on my numbers. Several years down the line, on a reduced carb way of eating my A1c meanders between 30 and 34, with a low of 29, so he is dumbfounded each time we meet. On that basis, I think predictions are worthless.

Those are very respectable numbers! Sounds like lifestyle still counts for a lot, your endo probably isn't used to someone actually making changes. In terms of myself, my brain tumor is benign (it's a vestibular schwannoma), but ketosis may still help? It's hard to say, supposedly lifestyle plays no part although I'm skeptical, but I'll need surgery due to its size regardless of diet. It's possible the tumor has been the problem for the last ten years since I may have had it that entire time and possibly even longer. I feel fine below the neck, it's kind of a brain fog and dizziness that I've always attributed to blood glucose, but it may be the tumor likes carbs. Ketosis definitely improves those symptoms, at least partially.

 

[AndBreathe]

Thank you. MODY was my other suspicion back when I was trying to get help, but doctors refused testing for anything because my A1C was just out of the pre-diabetes range. I'd kind of forgotten about it, but I just looked and there are some more tests available if I want to go that route.


Those are very respectable numbers! Sounds like lifestyle still counts for a lot, your endo probably isn't used to someone actually making changes. In terms of myself, my brain tumor is benign (it's a vestibular schwannoma), but ketosis may still help? It's hard to say, supposedly lifestyle plays no part although I'm skeptical, but I'll need surgery due to its size regardless of diet. It's possible the tumor has been the problem for the last ten years since I may have had it that entire time and possibly even longer. I feel fine below the neck, it's kind of a brain fog and dizziness that I've always attributed to blood glucose, but it may be the tumor likes carbs. Ketosis definitely improves those symptoms, at least partially.

I'm not suggesting anything at all, in terms of the specifics of your ketosis or anything else you say, but there are great swathes of "medicine", wellbeing and performance influenced by belief in the remedy/treatment/approach/regime and confidence in the advisor guiding us. Those believing the way forward will very often have better outcomes than those who do not believe.

There's a lot to be said for positive mental attitude and belief, although, sadly, it can't conquer all. A closed mind becomes a dogma, which isn't what I mean by belief.

 

[MattInUSA]

but there are great swathes of "medicine", wellbeing and performance influenced by belief in the remedy/treatment/approach/regime and confidence in the advisor guiding us. Those believing the way forward will very often have better outcomes than those who do not believe.

I agree with you wholeheartedly. A positive attitude and belief (while not being close-minded) can make a huge difference in the outcome. I appreciate your input.