Why is my fasting glucose high?

A fasting glucose above the normal range - 100 mg/dL and up - has a short differential. Prediabetes or diabetes is the one to rule out: fasting 100-125 is the prediabetes band, 126 and above on two occasions is diabetes, per NIDDK. The dawn phenomenon: your body releases cortisol and growth hormone toward morning, nudging glucose up - everyone gets a bump; people with insulin resistance get a bigger one. Stress and poor sleep in the days before the draw push glucose up measurably. Illness, even a brewing cold, raises it. And the testing quirks: a snack you forgot, hand cream or fruit residue on the finger for a home test, dehydration, and lab variation. So one high fasting reading is a question, not a verdict: repeat it on a normal week, and pair it with an A1c - the three-month average - before any label sticks. That pairing is the standard NIDDK diagnostic logic: the fasting test catches the morning state, the A1c catches the average. What to do with a confirmed elevation: it is the prediabetes conversation - the 7 percent weight loss and 150 weekly minutes that reverse course - and re-testing on schedule. Fasting readings creeping upward year over year, even inside the normal range, are worth mentioning to your provider: the trend is earlier information than the threshold. Pymander is a free AI doctor, 24/7 by text. Share the number and the context, and it can help you read it.