Random glucose optimal range and reference range
Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026
Sera's bands for Random glucose:
- Optimal 70 – 140 mg/dL (3.9 – 7.8 mmol/L); out of range below 70 or above 140 mg/dL.
Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.
All units
| Unit | Optimal | Sufficient | Out of range |
|---|---|---|---|
| mg/dL | 70 – 140 | — | below 70 or above 140 |
| mmol/L | 3.9 – 7.8 | — | below 3.9 or above 7.8 |
No separate Sufficient band is currently defined for this marker.
What the evidence says
The band is Mayo Clinic Laboratories' random glucose interval, 70 to 140 mg/dL, and North Bristol's non-fasting upper limit of 7.8 mmol/L. A German cohort followed for 11.7 years found mortality was not significantly raised below 7.8 mmol/L and doubled from 7.8 to 11.0. A result above 7.8 is not a diagnosis, but usually leads to an HbA1c or a fasting glucose; some NHS laboratories ask for a fasting test above 6.0. The ADA and NICE diagnose diabetes from a random result only at 11.1 mmol/L (200 mg/dL) or more with symptoms. Below 3.9 mmol/L (70 mg/dL) is low blood sugar, although UK laboratories print lower limits of 3.0 to 3.8. There is no optimal band: the value depends on when and what the client last ate. A glucose that the report does not label as random or non-fasting is read as fasting glucose.
Sources
- Test ID GLURA Glucose, Random, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceMayo's reference value for a random serum glucose from age 1 year: 70 to 140 mg/dL. Both of Sera's mg/dL edges.
- Glucose (outpatients/General practice) — Severn Pathology, North Bristol NHS Trust, 2026 · Laboratory / reference-interval sourceNHS GP reference range: non-fasting 3.0 to 7.8 mmol/L (fasting 3.0 to 6.0). Sera's upper edge of 7.8 mmol/L; its lower limit of 3.0 is lower than Sera's 3.9.
- Association between random glucose and all-cause mortality: findings from the mortality follow-up of the German National Health Interview and Examination Survey 1998 — Baumert J, Heidemann C, Paprott R, Du Y, Scheidt-Nave C — BMC Endocrine Disorders, 2018 · Peer-reviewed publicationIn 5,955 German adults without known diabetes, mortality was not significantly raised below 7.8 mmol/L and doubled from 7.8 to under 11.1 (HR 2.02). Outcome support for Sera's upper edge of 7.8 mmol/L.
- 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes—2026 — American Diabetes Association Professional Practice Committee — Diabetes Care, 2026 · Clinical guidelineLevel 1 hypoglycaemia is glucose below 70 mg/dL (3.9 mmol/L). Written for people with diabetes; supports Sera's lower edge alongside Mayo's lower limit.
- 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026 — American Diabetes Association Professional Practice Committee — Diabetes Care, 2026 · Clinical guidelineA random plasma glucose of 200 mg/dL (11.1 mmol/L) or more diagnoses diabetes only with classic symptoms or a hyperglycaemic crisis. A diagnostic threshold, which is why it is not Sera's upper edge.
- Diabetes - type 2: Diagnosis in adults — NICE Clinical Knowledge Summaries, 2026 · Clinical guidelineThe UK criterion: random plasma glucose of 11.1 mmol/L or more with symptoms or signs of diabetes. NICE gives no intermediate random-glucose zone.
- Glucose (plasma) — University Hospitals Sussex NHS Foundation Trust, Pathology, 2026 · Laboratory / reference-interval sourceA stricter NHS laboratory: it recommends a fasting glucose when a random result is above 6.0 mmol/L, and treats 11.1 or more as diagnostic only with symptoms.
What Glucose (Random / Non-Fasting) measures
Blood glucose drawn without fasting, at any time of day.
Shows where blood sugar sits on an ordinary day, so it moves with the last meal and cannot be read against fasting targets. A raised random glucose is a reason to check HbA1c or a fasting glucose, not a diagnosis on its own.