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interpreting self administered GTT

P

piersie

Member
Messages
8
Type of diabetes
Type 2
I wonder if any one can help me understand my self administered test. Background I was diagnosed with type 2 30 months ago wiht an hba1c of 64. I was offered metformin but chose the newcastle diet first. Blood glucose on first day was 13.5 it had dropped below 5.5 within 7 days. I lost 3 stone of which I subsequently regaind 1/2 so I am 2 1/2 stone lighter than when I started. Since then I have adopted a fairly low carb diet and for the last 30 months my hba1c's have been below 40. I was told I could come off the register but chose to stay on it as I wanted to keep testing and needed the strips. Knowing if I stopped testing I would go back to my bad old ways.
I normally work on 20-30g of a fast acting carb like bread or porridge to be my max at a sitting if I want to keep my 1 hour and 2 hour blood glucose < 7.6.
Out of curiosity I did a GTT using 75g of glucose using lucozade. I then tested my blood sugar at 1/2 hour intervals.


0 minutes - 4.8
30 minutes - 8.5
60 minutes - 12.5
90 minutes - 9.5
120 minutes - 4.1

It was pretty uncomfortable seeing my blood sugar going so high and I am confused what is going on. Clearly this is an abnormal response as it shouldn't have gone so high, but with the current criteria I would be considered non-diabetic as my glucose had returned (in fact overshot) my base rate by 2 hours.
My confusion is that for that to happen I obviously can produce enough insulin. Even at those high glucose levels I am able to shift the glucose out of the blood so I can't be massively insulin resistant anymore. Why in that case would the levels rise so high (even crossing the renal threshold) before the insulin kicks in. Is it possible that after years of beer drinking my pancreas expects a raised blood glucose to be followed by a glucose drop and therefore doesn't respond straight away. Or would that be considered pop-endocrinology !
 
I would not take a self administered GTT as being anything accurate as you do not have any blood tests when you do it yourself so why not ask your doctor if you think you need one.
I had mine done at my local hospital a blood test was done when I got there then I had the glucose drink and a two hour wait before the next blood test when me and a couple of others having it done were not allowed to go walking around because the large amount of glucose they said can make you feel dizzy or even faint so they wanted to keep an eye on us. After the two hours had another blood test then home
 
You are controlling your diabetes with diet. You are still diabetic. Your first phase insulin response is not normal but your second phase still works. This is common for type 2. Getting a proper test done in a lab would be much more accurate.
 
It sounds to me as if the OP, @piersie has made a pretty good job of doing a home GTT. There are regular blood sugar tests, taken with a meter which will have a satisfactory level of accuracy for these purposes and there is a clear result. I presume that s/he knew to remain seated throughout the two hours, so that activity did not affect the result. However, s/he does not mention "carbing up" for a few days before the test, which low-carbers are always advised to do. This could have been the cause of the initial rapid rise - the body does not keep a large supply of insulin in a ready-to-go form for people who don't use it.
@piersie could repeat the test, having increased his/her carb levels for a few days before hand, but why bother. S/he is on a reduced (not low) carb diet and appears to be doing well on it - why change things? Going back to beer and cake would just be going back to square one.
Sally
 
For the GTT, I was only told not to eat after 22:00. I walked half a mile to the hospital and then walked during the 2hr wait.
Based on the result,(can't remember result, but wasn't bad) hospital said I was T2, on fasting, GP said I was Pre-diabetic and Hba1c of 25, nurse said I was normal.
 

Yes, my surgery ballsed up my first 2 OGTT too, something rotten.
I was told to 'eat normally' so I did. My idea of 'normal' is low carb.
They sent me home during the test (walk to car, drive, walk from car to house, which was about 100 yards, due to parking issues, and a couple of trips upstairs during the 2 hours, then the return journey to the surgery)
And they were 10 mins late to do the second test.

At the time of the first 2 tests, I didn't have a meter, so I didn't test every few mins to see how high my bg rose.

By the third test, I had brought my self up to speed, although they were late with the 2 hour test, as usual.
 
thanks folks. Yes I remained seated during the two hours. No I didn't up my carbs beforehand. I am a 'he'.
The purpose of testing was to understand better what is going on in my body. Though I am fairly comfortable with my low carb diet at home it is a pain in the A when I am travelling on business. At home I stick to cauliflower, celeriac, legumes, leafy greens etc and it works fine. That is not so easy in hotels in foreign cities so I wanted to understand better what would happen if I relaxed my regime a little. I think the point about the first phase insulin response is on the button. Does anyone know if there is a way to preload the second phase, i.e. have a bread stick, wait 20 minutes then eat ?
Thanks Piersie
 
If you are a low carber, and if you don't eat "normal" carbs for 2 to 3 days beforehand you are almost certain to fail an OGGT.

Your pancreas is used to having very few carbs, and therefore glucose, to deal with and so only produces sufficient insulin to cope with the glucose level it is used to. If you then hit it with a big drink of pure glucose it will be unprepared and only produce the small amount of insulin it normally does. It then has to have a re-think and produce some more, but this takes a bit of time. Hence the big spike.

If you try it again you need to eat normal carbs for those 2 to 3 days beforehand.
 
thanks bluetit. I don't think I will try it again in the short term, it was a curiosity thing and I am happy to accept the explanations. It all helps in the management to understand what is going on though !
 
piersie said:
thanks bluetit. I don't think I will try it again in the short term, it was a curiosity thing and I am happy to accept the explanations. It all helps in the management to understand what is going on though !
Click to expand...

Using the same principle, if a low carber has a bit of a binge one meal, maybe a celebratory meal out for example, he can expect to spike a lot higher than he might if he had been eating that way regularly. The pancreas doesn't expect it. It is known as the "last meal effect".
 

The answer is simple you need to test every food that you eat in every portion size and every combination, it took me a year of testing pre and postprandial every meal I ate to gain an insight into how my body reacts to various food stuffs in various combinations and although I wouldnt say I know it all I have a pretty good idea what my blood glucose is likely to be throughout the day now.

I was lucky in that I was using insulin for 12 months after my T2 diagnosis so had no alternative but to test every meal during that time but It paid off and I cant recommend it highly enough.

Stuff like knowing that adding vinegar to chips makes a huge difference in allowing me to safely eat what I want to eat but I wouldnt have found that out unless I had been told about it and tried and tested it for myself so that I know what portions of foods like chips I can eat, you cant be told this stuff as we are all different, you can only find it out for yourself by testing, everything..

Test, test and test again.


Edit: "The answer is simple" Actually its not simple at all it takes a long time and a lot of test strips but it does work and it is worth the effort.
 
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