Blood glucose concentration after an overnight fast.
It is a cheap, universally available first look at glucose handling, and one of the few markers with genuinely standardized diagnostic cutoffs.
Measured in mg/dL. Each row is one claim about where your result should fall.
Established diagnostic thresholds in wide clinical use
Metabolic health platforms and CGM subscriptions
| Claim | Range | Source |
|---|---|---|
| Laboratory reference range | 70–99 mg/dL | Established diagnostic thresholds in wide clinical use |
| 70–85 mg/dL | 70–85 mg/dL | Metabolic health platforms and CGM subscriptions |
Where the sources disagree
Fasting glucose is a late signal. Insulin resistance typically develops years before fasting glucose moves, because the pancreas compensates by producing more insulin. A normal fasting glucose is therefore weak reassurance on its own, which is a real argument for pairing it with fasting insulin, and also the argument every CGM subscription uses to sell you a sensor. Both things are true at once.
Each claim gets its strongest possible case before it gets its criticism. Several of these are substantially correct.
70–85 mg/dL
Promoted by metabolic health platforms and cgm subscriptions
Large cohorts show risk rising within the conventionally normal range, so the upper 90s are not risk-equivalent to the low 80s.
A single fasting glucose has substantial day-to-day variation: stress, poor sleep, or a hard workout the previous evening all move it. Flagging a one-off reading of 94 as suboptimal manufactures concern from ordinary biological noise.
One email when a reference range changes, a panel claim is corrected, or a regulatory status actually moves, not when something is merely proposed. No sponsors from any company we rate.
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