OGTT and C-Peptide - who should test for those?

[binnieman]

As you all know, Pre-D is even more confusing than T2 itself. So please bear with me while I get all the basics down. I am also going to read that book "Know your numbers..."

Who needs to do OGTT test? I am wondering because I do two-hour post meal tests and they are generally well within the normal range. But they vary quite a bit depending on what I ate but not close to 140 thus far. I was thinking that sugary solution might raise my BG up higher than normal. So given my FBG numbers hovering right around 100, HbA1c 5.6%, and the aforementiond post meal values, would it be useful for me to do OGTT? Can I improvise one at home?

Also Ronin can not emphasize enough the importance of C-Peptide test for people like me who are thin and show not completely normal BG values. If my post-meal numbers are good, does that mean I am producing sufficient insulin and that C-Peptide would be redundant for me? My doctor has turned against me because I asked her the fundamental questions that you guys graciously answer here for free. I thought I seek some opnions here before I go to her again. I am considering switching providers but most of them seem to have out-dated information anyway.

[sarahspins]

Insulin resistance tends to "go along with" being overweight, but not always.. c-peptide in a pre-diabetic or T2 can be a means of seeing just how much IR you have by getting a snapshot at how much insulin your pancreas is producing. Some people have significant IR without carrying any excess weight.. it can be very individual.

As far as if knowing your c-peptide is useful.. if you are't on any meds, and don't require them, probably not.

As for improvising an OGTT... I don't really know how helpful this would be, considering the margin of error on most home meters. You could get results that are fairly far off the mark, but really aren't diagnostic of anything at all.

[Ronin]

Hi Binnieman, et al.,

The reason I promote the C-Peptide test is to know where you are headed. The reason is simple -- avoid medications that don't work and only give the nasty side effects while the MD muddles around trying a host of meds only to discover, much later, that you aren't a Type-2 and should have been taking insulin all along.

I've noted this particular problem with more than a few fellow bicyclists who have been diagnosed as Pre-D and despite lifestyle modifications continued to see their BG levels go up. They have then suffered the diahreah and other wonderful effects of the meds prescribed while the BG remains high. Then after months (and in one case well over a year) finally get the C-Peptide in conjuction with an OGTT to discover that the pancreas has all but shut down completely.