My question is: how can I have a none pre-diabetic fasting blood glucose level demonstrated by an Accucheck monitor, yet also have an almost pre-diabetic level when measured by HbA1C?
These numbers are very close to mine (fasting 4.9; HbA1c 41). Based on rather frequent readings, my average HbA1c for the last 3 years has been 42, while until very recently, the fasting BG was 4.7.
The answer to your question has many parts. Overall, either your physiology is genuinely dysglycaemic, and/or the test is falsely high (in the sense of: what is the test result's true correlation to the BG level?). Two tactics to try in order to lower the 40 result are becoming more physically active and eating less carb.
As for the physiology, at one level of analysis, there are two kinds of hyperglycaemia: premeal glucose is too high; glucose tolerance is insufficient. The first is called "impaired fasting glucose" (IFG), while the second is called "impaired glucose tolerance" (IGT). GT is a phenomenon of the "postmeal" period (which includes any time after the person has started eating or drinking).
As you discovered, you are way below the threshold for IFG. Among prediabetics, roughly speaking 60% have IGT only, 25% have IFG only, and the remainder have both.
Glucose tolerance means the body keeps the blood level low -- "glucose disposal". Good tolerance consists in BG rises which are low and brief. There are several factors of GT, including insulin production, insulin release, and insulin resistance (IR).
Insulin release or secretion is a neglected and little understood topic in diabetes research, which is unfortunate for who don't have IR or loss of production. Physiologists speak of "insulin response" to eating or drinking. There is first phase insulin response and second phase. The research literature says that failure of first phase response or "secretion" may be the initiating event in both Type 2 and Type 1. The body is quite capable of producing the hormone, but the delivery is obstructed. Insulin is supposed to be stockpiled in between meals, and in the first phase insulin response, this reserve is secreted or released when the person starts eating.
"Insulin resistance" is an attribute of liver, interior fat, and skeletal muscles. It may be low in one tissue and high in another. In Type 2 prediabetes, as the disease progresses, insulin resistance increases.
As for the scientific validity of the HbA1c test, there are many "interferences" with it. Although they are recognized by the diabetes authorities, most of them cannot be tested for (unless you are a participant in a scientific experiment) and there are no specified adjustments even for those that can be sort of tested for. For example, if you are mildly anaemic (red blood cell count is low), the A1c result will be too high. But nobody can say how much too high. There are also no standards, there is no provision made, for adjusting the A1c value by so much given an anaemia value of so much.
