Normal Fasting Glucose mg/dL — Am I Normal?
First reading of the morning, water only since waking. CGM-friendly.
What's a normal fasting blood glucose in mg/dL?+
ADA criteria: under 100 mg/dL is normal; 100–125 is pre-diabetic; 126+ on two separate occasions is diabetic. Longevity-focused practitioners (Attia, Casey Means) tighten the "optimal" band to 70–90 mg/dL — the upper end of "normal" (94–99) already correlates with worse cardiovascular outcomes in non-diabetics.
Is 90 a good fasting glucose?+
Yes, 90 mg/dL is comfortably inside the optimal longevity range (70–90). Most healthy adults with good metabolic health sit in the 80–95 window on most mornings.
Why does my fasting glucose vary so much day-to-day?+
Stress, poor sleep, late dinner, or an evening workout can each push fasting glucose 10–20 mg/dL above baseline. A single reading is noisy — three readings on three normal days, ideally averaged with a 14-day CGM, is much more reliable.
Do I need a CGM if I'm not diabetic?+
A 14-day CGM audit (FreeStyle Libre 3, Dexcom Stelo, Nutrisense, Levels) is the cheapest way to see how specific meals affect *your* glucose. After 14 days you have what you need; ongoing wear is mostly diminishing returns unless you're actively troubleshooting.
What's the relationship between fasting glucose and HbA1c?+
HbA1c reflects average glucose over the prior ~3 months. Fasting glucose is one point-in-time reading. They usually agree but can diverge: someone with high postprandial spikes can have normal fasting glucose and elevated HbA1c. Order both on the same blood draw — they're cheap.
What's a normal fasting blood glucose in mg/dL?
ADA criteria: under 100 mg/dL fasting is normal; 100–125 is impaired (pre-diabetes); 126+ on two separate occasions is diabetic. Most longevity-focused practitioners (Attia, Casey Means, Levels) tighten the 'optimal' band to 70–90 mg/dL, citing that the upper end of 'normal' (94–99) already correlates with worse cardiovascular outcomes and cognitive performance in nondiabetics.
A single morning reading is noisy. Stress, poor sleep, late dinner, or an evening workout can each push fasting glucose 10–20 mg/dL above baseline. Three readings on three separate normal days, ideally averaged with a continuous glucose monitor over a 14-day window, is much more reliable than a one-off finger-stick.
Glucose, ApoB, hsCRP — the cluster that actually matters
Fasting glucose is one of three cheap blood markers that together explain most of the cardiometabolic-risk story for otherwise-healthy adults: fasting glucose (insulin resistance), ApoB (atherosclerotic burden), and hsCRP (inflammation). Optimizing any one in isolation can mask the others. The polls / tools in this cluster are designed to be used together rather than chasing a single number.
See how you compare.
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