### Human:\nmy hgba1c is 9. 1 and my fasting blood sugar is 92. is this idicative of diabetes? . my vitamin d is also low. my doctor has prescribed a prescription for that and he wants to repeat the hgba1c. i'm not sure if that can alter the test or not.\n\n### Assistant: although studies show low vitamin d is linked to poor diabetes control it wouldn't necessarily give you a false reading. a hemoglobin a1c higher than 6. 5% indicates diabetes. the fact that your fasting blood glucose was normal is probably why your doctor is having you re-take your hemoglobin a1c. hopefully the second test will give you some clarity. the a1c is the average of your readings for 6 months. a 9. 1 reading puts your average reading at around 170. average not exact. that is diabetic. mornings without eating should average 80 - 130. two hours after eating should be under 180. if the 170 is a fasting reading you have diabetes. my opinion and what i was told in classes. not all methods for measuring hba1c are totally specific -one of the usual substances incriminated is hb f or foetal haemoglobin which only should usually be present in small amounts in adult blood however some people do carry larger amounts which can interfere with the assay.