What does the Glucose test measure?

Why is Glucose measured?

Fasting glucose is the first-line screening test for diabetes (≥126 mg/dL on two occasions) and pre-diabetes (100–125 mg/dL). Random or non-fasting glucose is less specific but values ≥200 mg/dL with symptoms are diagnostic. Hypoglycaemia (below 70 mg/dL) prompts evaluation for excess insulin, adrenal insufficiency, or glycogen-storage disorders. Glucose is time-sensitive and requires prompt separation to avoid ex vivo glycolysis by blood cells.

Reference ranges

Standard reference

Fasting approximately 70–99 mg/dL (3.9–5.5 mmol/L); non-fasting specimens are interpreted against different thresholds.

Functional medicine optimal

Fasting 70–85 mg/dL (3.9–4.7 mmol/L) is often cited in metabolic-health and longevity literature, though 70–99 mg/dL remains the guideline-endorsed normal range.

Units

mg/dL, mmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.