Capillary vs venous glucose

[Doireallyneedanams]

Hi all.

I have posted before about issues surrounding my “diagnosis” of gestational diabetes at 37 weeks pregnant.

I never had any GD symptoms during my pregnancy to suggest it, baby measured normal, amniotic fluid fine, no glucose in urine etc. However late in my pregnancy I had a sibling diagnosed with type 2 which meant I would ordinarily have had an OGTT. It was too late for that so the hospital had me monitor my bloods at home for a week.

They wanted all readings under 7.8 at one hour and a diagnosis of GD was made when I had 3 readings over this. (7.8, 7.9, 8.4) All three were after take aways and the 8.4 was after 120g worth or burger, chips & deep fried pasta.

Hba1c was done at 37 weeks and it was 33. “Falsely low in pregnancy” Dr Google screamed at me, after endless reading I concluded it could have been correct but it could have also been around 38.

Naturally I have been ridden with anxiety ever since, almost one year down the line. I have read tonnes of studies showing that non diabetics spike above 7.8 regularly.

My diet has been free of all refined carbs ever since, with the occasional “treat” once every couple of months or so. Hba1c came back as 30 five months postpartum. More panic ensues, as I thought it would have been significantly lower given my extreme change in diet. (In pregnancy my diet was 200g+ refined carbs + added sugars per day)

Anyway, I still regularly test and as I’ve been low carb rarely see anything above 6.5 at one hour which swiftly drops back to fasting by 3. However yesterday after a moment of weakness, some crisps & chocolate later (30g carb) I got 7.4 at 45 mins down to 6.5 at an hour. The “7” panicked me, and I started researching again.

NOW I read that it’s well known in medicine that capillary glucose is higher than venous, so why do hospitals get away with diagnosing on home reads? If my reads bad been distinctly high and often (10, 11 etc) I could understand, but with 7.9, 7,8 & 8.3 this suggests they could have been well within normal range had a venous sample been taken. My fasting was always and has always been 4.4-4.8)

I don’t want to contribute to this Covid mess by insisting on an OGTT at the hospital right now (if my GP would even agree to it) but can someone tell me what they think?

I am sick of worrying about having masked and undiagnosed prediabetes/type 2. In many ways this was the wake up call I needed seeing as it’s in my family, but worrying like this over something that may not even be is truly exhausting.

I’m too scared to do my own OGTT as I know it’s not even that reliable at home and doing it with a glucose monitor won’t be precise it seems.

 

[NicoleC1971]

Hi all.

I have posted before about issues surrounding my “diagnosis” of gestational diabetes at 37 weeks pregnant.

I never had any GD symptoms during my pregnancy to suggest it, baby measured normal, amniotic fluid fine, no glucose in urine etc. However late in my pregnancy I had a sibling diagnosed with type 2 which meant I would ordinarily have had an OGTT. It was too late for that so the hospital had me monitor my bloods at home for a week.

They wanted all readings under 7.8 at one hour and a diagnosis of GD was made when I had 3 readings over this. (7.8, 7.9, 8.4) All three were after take aways and the 8.4 was after 120g worth or burger, chips & deep fried pasta.

Hba1c was done at 37 weeks and it was 33. “Falsely low in pregnancy” Dr Google screamed at me, after endless reading I concluded it could have been correct but it could have also been around 38.

Naturally I have been ridden with anxiety ever since, almost one year down the line. I have read tonnes of studies showing that non diabetics spike above 7.8 regularly.

My diet has been free of all refined carbs ever since, with the occasional “treat” once every couple of months or so. Hba1c came back as 30 five months postpartum. More panic ensues, as I thought it would have been significantly lower given my extreme change in diet. (In pregnancy my diet was 200g+ refined carbs + added sugars per day)

Anyway, I still regularly test and as I’ve been low carb rarely see anything above 6.5 at one hour which swiftly drops back to fasting by 3. However yesterday after a moment of weakness, some crisps & chocolate later (30g carb) I got 7.4 at 45 mins down to 6.5 at an hour. The “7” panicked me, and I started researching again.

NOW I read that it’s well known in medicine that capillary glucose is higher than venous, so why do hospitals get away with diagnosing on home reads? If my reads bad been distinctly high and often (10, 11 etc) I could understand, but with 7.9, 7,8 & 8.3 this suggests they could have been well within normal range had a venous sample been taken. My fasting was always and has always been 4.4-4.8)

I don’t want to contribute to this Covid mess by insisting on an OGTT at the hospital right now (if my GP would even agree to it) but can someone tell me what they think?

I am sick of worrying about having masked and undiagnosed prediabetes/type 2. In many ways this was the wake up call I needed seeing as it’s in my family, but worrying like this over something that may not even be is truly exhausting.

I’m too scared to do my own OGTT as I know it’s not even that reliable at home and doing it with a glucose monitor won’t be precise it seems.

I think the reason for the finger prick test in this case is that it is obviously more practical than a venous draw although the hba1c that you get on a venous draw is a more accurate 'mean average' (equivalent to 100,000 prick tests according to Ken Silvas). However those prick tests are giving you some useful info about how you react to processed carbs and I'd say most people do much better without those foods from the point of view of wider metabolic health (t2 diabetes, hypertension, weight gain, dementia, some cancers ).
If you feel better and you arleady know you have at least 1 risk factor (sister diagnosed with type 2) I would keep going without the processed carbs and perhaps test fasting or 2 hours after a carby meal just to remind yourself what those foods tend to do!
Also 'normal' isn't the same as 'common' with these things. so a lot of people these days do eat a carby diet and may often get higher blood sugars as a result but this doesn't change the biological reality that those blood sugars and insulin spikes aren't healthy in the long term.
Which brings me to insulin. If you have an elevated insulin level you will eventually become insulin resistant leading to the conditions mentioned above of which type 2 is only one. So other than blood sugars Doctors should be looking at fasting insulin levels or proxies for that e.g. your triglyceride level exceding your hdl cholesterol as this would head all those problems off at the pass (if patients then changed their diets in the way that you have).
Pregnancy and adolesence are both times of growth and we have some natural insulin resistance to support this so we can't know if you were or weren't diabetic at the time given you didn't have an 0gtt and the hba1c is inaccurate due to the increased blood volume.
Going forward I'd stick to the great habits you've started as this means you'll at least delay or permanently delay your chances of getting type 2. If you did go on to develop it there are great ways back that you can see on this site which don't involve drugs so try and get these worries in context given that you've made a healthy normal baby and are now doing the right things most of the time!

 

[Doireallyneedanams]

I think the reason for the finger prick test in this case is that it is obviously more practical than a venous draw although the hba1c that you get on a venous draw is a more accurate 'mean average' (equivalent to 100,000 prick tests according to Ken Silvas). However those prick tests are giving you some useful info about how you react to processed carbs and I'd say most people do much better without those foods from the point of view of wider metabolic health (t2 diabetes, hypertension, weight gain, dementia, some cancers ).
If you feel better and you arleady know you have at least 1 risk factor (sister diagnosed with type 2) I would keep going without the processed carbs and perhaps test fasting or 2 hours after a carby meal just to remind yourself what those foods tend to do!
Also 'normal' isn't the same as 'common' with these things. so a lot of people these days do eat a carby diet and may often get higher blood sugars as a result but this doesn't change the biological reality that those blood sugars and insulin spikes aren't healthy in the long term.
Which brings me to insulin. If you have an elevated insulin level you will eventually become insulin resistant leading to the conditions mentioned above of which type 2 is only one. So other than blood sugars Doctors should be looking at fasting insulin levels or proxies for that e.g. your triglyceride level exceding your hdl cholesterol as this would head all those problems off at the pass (if patients then changed their diets in the way that you have).
Pregnancy and adolesence are both times of growth and we have some natural insulin resistance to support this so we can't know if you were or weren't diabetic at the time given you didn't have an 0gtt and the hba1c is inaccurate due to the increased blood volume.
Going forward I'd stick to the great habits you've started as this means you'll at least delay or permanently delay your chances of getting type 2. If you did go on to develop it there are great ways back that you can see on this site which don't involve drugs so try and get these worries in context given that you've made a healthy normal baby and are now doing the right things most of the time!

Thank you for the response. I suppose my concern is that if i do indeed have type 2 and have masked it, I am currently prone to many more issues and should be having a completely different relationship with my GP etc than I do currently (non existent unless I am sick, which is rare) - so to not “know for definite” sends my anxiety spiralling.

The diabetic team told me there was no chance I had type 2 as my hba1c would have been higher even in pregnancy, and my finger tests would have been higher too. I suppose this makes sense as my sibling had a random test of 16 mmol at diagnosis. Still, I worry.

 

[Ronancastled]

If you really want to run a home OGTT you can order the 75g Glucose solution online.
I didn't have the solution to hand when I ran mine so I used Jelly Beans & Jelly Babies, see here.
https://www.diabetes.co.uk/forum/threads/jelly-babies-instead-of-rapilose-for-home-ogtt.175741/

The efficacy of using Jelly Beans as a substitute for the glucose solution is covered here:
https://pubmed.ncbi.nlm.nih.gov/10561636/

I've since been told that the 75gs of carbs are not made up of pure glucose & there's a fructose element that can skew the results.
It was good enough for me as everyone around here say that carbs are carbs & as we never chug down large quantities of glucose it's more representative of "normal" food.

Let us know your results, it's worth taking a reading every 30 mins, here's the criteria.

 

[Doireallyneedanams]

If you really want to run a home OGTT you can order the 75g Glucose solution online.
I didn't have the solution to hand when I ran mine so I used Jelly Beans & Jelly Babies, see here.
https://www.diabetes.co.uk/forum/threads/jelly-babies-instead-of-rapilose-for-home-ogtt.175741/

The efficacy of using Jelly Beans as a substitute for the glucose solution is covered here:
https://pubmed.ncbi.nlm.nih.gov/10561636/

I've since been told that the 75gs of carbs are not made up of pure glucose & there's a fructose element that can skew the results.
It was good enough for me as everyone around here say that carbs are carbs & as we never chug down large quantities of glucose it's more representative of "normal" food.

Let us know your results, it's worth taking a reading every 30 mins, here's the criteria.

Thanks. I don’t think it’s a good idea for me to do it at home given the variability in meter reads. If i tested at 9.5 as an example I’d be terrified until speaking to a doctor for a lab OGTT.

 

[Ronancastled]

Thanks. I don’t think it’s a good idea for me to do it at home given the variability in meter reads. If i tested at 9.5 as an example I’d be terrified until speaking to a doctor for a lab OGTT.

I think you'll be just fine.
Glucose meters are calibrated to read lower to compensate for the difference between venous & capilary blood anyway.
The adjustment is already built into the meter.

 

[Doireallyneedanams]

I think you'll be just fine.
Glucose meters are calibrated to read lower to compensate for the difference between venous & capilary blood anyway.
The adjustment is already built into the meter.

From what I’ve read whilst that is the case for fasting, apparently it is not the case for post prandial reads. I could stand corrected however!

My healthy non diabetic partner recently asked to test after a 55g monster energy drink and hit 8.4 at one hour, yet online it says a non diabetic will “never” go above 7.8.