Value of Glucose Tolerance/Insulin Test

[Paleowoman]

I know that I feel LOUSY with too many carbs and rapidly gain fat when I overindulge in them. It's obvious to me that the more I stay away from excessive carbs the better -- I tend to feel best on under 30 or 40 per day depending on my activity level. Why then would I ever want to take a Glucose Tolerance Test which requires 3 days (9 meals) of ULTRA HIGH CARBS :eek: -- a TOTALLY UNNATURAL diet for me just to prove what I already know from experience? I ask this because a new doc wants me to have a "special one" done at his office with insulin component included, not just blood glucose -- takes 5 hours and costs nearly $400. I asked the nutritionist there what the protocol would be if the test results indicated I had prediabetes, insulin resistance etc. and she said dietary carbohydrate restriction WHICH I ALREADY DO. Anyone else out there hesitant to have this test. I can see the value for someone who is clueless about the effects of too much carbohydrate in the diet and who already eats the SAD, but I'm a veteran with THIS way of eating. My view is they should just consider me pre-diabetic, insulin resistant -- both parents and only sibling are type 2 diabetics. So that and obesity runs in my family. Eating lowcarb I am middleaged female and 5'2.5" tall and weigh 111 pounds with more than average muscle as I work out strenuously. My triglycerides are 55 -- fasting glucose 79 to 80ish. HDL 104; LDL 177. I have a hypothyroid condition. Thoughts?

[Gabriel Guzman]

Well, with those values of triglycerides, HDL and fasting glucose I'm rather envious!:)

Maybe you need to discuss with your doctor the value of such test. Obviously, your fasting glucose says a lot and you can actually measure your postprandial glucose (after eating) to see how your glucose response is. If the test intends to say anything about your insulin response, perhaps measuring serum insulin is more accurate than glucose tolerance. Tha ctual ratio of fasting glucose/serum insulin is more indicative of insulin resistance than the results of a glucose tolerance test, in my opinion. Just as important to know how much glucose, is to know how much insulin it's taking to keep your blood glucose levels.

Normally, fasting glucose levels of more than 115 mg/dl in a person already indicate some lose of control in blood sugar but yours is way below that, however, a clearer picture arises if the insulin values are also considered.

[mcsblues]

Perhaps rather than a GTT which seems pretty pointless given your experience and the diet you have already adopted to cope with it, you could perhaps convince your doctor to perform the insulin challenge test the Eades describe in PPLP (?) which would give you a much clearer yardstick in any changes to insulin sensitivity - which is of more significance anyway - and as far as I recall, does not require carb loading for days preceding the test.

[Paleowoman]

Perhaps rather than a GTT which seems pretty pointless given your experience and the diet you have already adopted to cope with it, you could perhaps convince your doctor to perform the insulin challenge test the Eades describe in PPLP (?) which would give you a much clearer yardstick in any changes to insulin sensitivity - which is of more significance anyway - and as far as I recall, does not require carb loading for days preceding the test.

If this new doctor doesn't fire me as a patient, I'll ask about the insulin challenge test. But supposing it shows changes in insulin sensitivity -- then what? Isn't the "treatment" still low carb diet?

[kevinpa]

If this new doctor doesn't fire me as a patient, I'll ask about the insulin challenge test. But supposing it shows changes in insulin sensitivity -- then what? Isn't the "treatment" still low carb diet?

I have to agree that it is a moot point since no matter the outcome a low carb diet is the path you will be following. What I wonder is if it would show you are not prediabetic would he suggest you did not eat low carb?

[Paleowoman]

Well, with those values of triglycerides, HDL and fasting glucose I'm rather envious!:)

Maybe you need to discuss with your doctor the value of such test. Obviously, your fasting glucose says a lot and you can actually measure your postprandial glucose (after eating) to see how your glucose response is. If the test intends to say anything about your insulin response, perhaps measuring serum insulin is more accurate than glucose tolerance. Tha ctual ratio of fasting glucose/serum insulin is more indicative of insulin resistance than the results of a glucose tolerance test, in my opinion. Just as important to know how much glucose, is to know how much insulin it's taking to keep your blood glucose levels.

Normally, fasting glucose levels of more than 115 mg/dl in a person already indicate some lose of control in blood sugar but yours is way below that, however, a clearer picture arises if the insulin values are also considered.

Speaking of fasting glucose -- I posted what my numbers have been for my last several physicals. This new doc also took a fasting glucose test but I haven't heard the results yet. His office insisted I schedule the GTT BEFORE my fasting glucose test results are in because "everybody gets the GTT). By the time his office took my blood -- I had been fasting for 17 hours! It took 4 attempts for them to get the blood out of my arm - something which has NEVER EVER happened to me before. Would fasting for an unusually long time ie more than the usual 13 or 14 hours drive my blood glucose down abnormally low or up abnormally high or should it not make much of a difference?

[Gabriel Guzman]

When fasting for a long time, the liver takes care of keeping blood glucose levels constant, so if everything is fine, your blood glucose shouldn't change appreciably. Uncontrolled diabetics, on the other hand, may present higher values of fasting glucose because their liver tends to overproduce glucose.