Blood sugar: Fasting vs. postprandial 5. February 2010 William Davis (23) Peter's fasting blood glucose: 89 mg/dl--perfect. After one whole wheat bagel, apple, black coffee: 157 mg/dl--diabetic-range.How common is this: Normal fasting blood sugar with diabetic range postprandial (after-eating) blood sugar? It is shockingly common. The endocrinologists have known this for some years, since a number of studies using oral glucose tolerance testing (OGTT) have demonstrated that fasting glucose is not a good method of screening people for diabetes or pre-diabetes, nor does it predict the magnitude of postprandial glucose. (In an OGTT, you usually drink 75 grams of glucose as a cola drink, followed by blood sugar checks. The conventional cut off for "impaired glucose tolerance" is 140-200 mg/dl; diabetes is 200 mg/dl or greater.) People with glucose levels during OGTT as high as 200 mg/dl may have normal fasting values below 100 mg/dl. High postprandial glucose values are a coronary risk factor. While conventional guidelines say that a postprandial glucose (i.e., during OGTT) of 140 mg/dl or greater is a concern, coronary risk starts well below this. Risk is increased approximately 50% at 126 mg/dl. Risk may begin with postprandial glucoses as low as 100 mg/dl. For this reason, postprandial (not OGTT) glucose checks are becoming an integral part of the Track Your Plaque program. We encourage postprandial blood glucose checks, followed by efforts to reduce postprandial glucose if they are high. More on this in future.