Why is my fasting glucose high?
Last updated September 3, 2026.
Fasting 100-125 is prediabetes, 126+ twice is diabetes - but confirm one high reading with a repeat plus A1c first, since dawn hormones, stress, illness, and quirks inflate single values.
What to do
- Repeat before concluding - one high reading is a question, per NIDDK diagnostic logic.
- Pair with A1c - the morning state plus the three-month average.
- Control the confounders - illness, stress, poor sleep, and residue inflate readings.
- Confirmed elevation: the prediabetes playbook - and watch year-over-year trends.
Related questions
- What is a normal A1c?
- Can prediabetes be reversed?
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