I’m in my 50s now and wondering how why my PCP has not ordered an A1c for me. (I have not been diagnosed with DM) As a curious nurse, of course I have given myself this test multiple times. But it makes me wonder why someone else has not ordered this test for me. I realize that the doc is likely looking at the fasting glucose during my annual labs (when I get them), but to me, there are few tests quite as useless as this one. Many if not most people’s BG after fasting 12 hours is usually in the normal range. My own is usually in the 90s, sometimes at 100, 101, rarely in the 80s.
I have for the last 10 years attempted to eat well - limiting refined foods, mostly, and the “low hanging fruit” of things like soft drinks. I have a definite sweet tooth and sometimes fall off the wagon, necessitating an imposition of a strict weeks-long no sugar diet. Childhood was a different story - I ate a lot of sugar.
My A1c, has been as low as 5 and as high as 5.6 or .7.
Is the FBG test as useless as I think it is? Especially for nondiabetics.
[If this post can be inserted into another thread, please do go ahead.]
Fasting blood glucose if 100mg/dl or above is a good indicator of insulin resistance. The feet on the floor syndrome is especially marked in us with the genes for insulin resistance.
If a person’s fBG is under 100 I don’t think it is reasonable to order the more expensive HbA1c test.
Individual numbers on a test panel that are just barely out of range - e.g. bg of 101 which may or may not be in reference range - usually don’t rate much notice.
If you are not diagnosed and suspect you might have some glucose intolerance and want to get the doc to run an A1C, just chow down on 75g-100g of sugar an hour before your “Fasting” (air quotes) glucose test. If you are 150+ on the fake FBG (reflecting at least some glucose intolerance) I’m sure your doc will run an A1C and may even send you for a glucose tolerance test.
If you have been working your butt off to normalize your bg’s and as a result are not getting a diagnosis I think that’s counterproductive. That’s like studying for the eye test by memorizing the chart before going to the eye doctor, and then not getting the glasses you actually need.
Knowing what 38 years of living with diabetes has taught me, if I was worried about my metabolic health and a possible T2D diagnosis (hypothetically, of course), I would choose to get a c-peptide test. The medical world watches glucose, a lagging indicator of T2D, instead of insulin, the early marker that something is wrong. I find this behavior puzzling.
In the case of T2D progression, the insulin output goes high years and decades before the glucose elevates to diagnosis levels. During those intervening years, a lot of hyperglycemia damage is done.
The c-peptide test gives an accurate account of just how much insulin the pancreas produces. There’s nothing wrong with FBG and the A1c test except that they don’t expose the impending metabolic trouble that a c-peptide check could reveal long before a T2D diagnosis emerges.
By the way, an A1c test can be had for as little as $12 (see UltaLabs). Any doctor who is trying to save $12 when monitoring my health, I would consider penney-wise and pound-foolish!
Doctors have to justify to insurance companies that a test is needed or they won’t pay for it. Fairly standard test but still is only done if there is a reason? So the general rule of thumb I think is that your fasting blood glucose level would be high if you were or are developing a problem. A fasting level would usually show a sign of something not being right.
Fasting levels don’t catch the fluctuations that happen at the start, but an A1c doesn’t either. If your fasting level is okay…the odds are most of the day you are probably in a pretty normal range. The first couple of years that my fasting level started to go higher I still tested in the A1c normal low 5’s for over a year so the A1c test wasn’t helpful to diagnose a problem.
Thanks Marie20. This is what I was truly wondering about. I was thinking that almost anyone who hasn’t eaten in 12 hours could show a normal or close to normal BG. In my experience as a nurse this is often true. But your comment also made me realize that it is not always true. (So at best, it is true sometimes, but not the foolproof test I think many doctors think it is.) And yes, if my FBG showed in the 110s or 120s or higher, it is likely that something has indeed changed for the worse.
Interesting, thank you.
Also, thanks very much to everyone else who weighed in. I guess my overriding concern is how to reliably track my health as I get older, staying out of the preDM and DM range, and I have been therefore questioning the usefulness of the FBG. I also realize that BG is a potential lagging indicator, and a couple of years ago, did an insulin test which was normal (3.9 iIU/mL on a scale of 2.6-24.9). I have not done the C Peptide test.
The official definition of diabetes is fasting blood sugar more than 7 mmol/l or 126 mg/dl, so FBG is the most popular diagnostic tool.
For management, FBG is almost always ordered and is of little use. It is very difficult for a Type I to keep a constant blood glucose level, and a single high value causes limited damage, it is the average value that is important, which can be measured by several different tests, e.g., HbA1c or fructosamine. Any test that measures average glucose level is good. A single fasting blood sugar is profitable, so popular, even it it gives almost no useful management information.
