For adults without diabetes, a normal fasting blood sugar is below 5.6 mmol/L (100 mg/dL), and a normal HbA1c is below 42 mmol/mol (5.7%). Fasting levels of 7.0 mmol/L (126 mg/dL) or higher, or an HbA1c of 48 mmol/mol (6.5%) or higher, are in the diabetes range when confirmed by testing. Here is a full chart in both units.
Blood sugar chart for diagnosis
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting plasma glucose | Below 5.6 mmol/L (100 mg/dL) | 5.6–6.9 mmol/L (100–125 mg/dL)* | 7.0 mmol/L (126 mg/dL) or higher |
| 2 hours after 75 g glucose (OGTT) | Below 7.8 mmol/L (140 mg/dL) | 7.8–11.0 mmol/L (140–199 mg/dL) | 11.1 mmol/L (200 mg/dL) or higher |
| HbA1c | Below 42 mmol/mol (5.7%) | 42–47 mmol/mol (5.7–6.4%) | 48 mmol/mol (6.5%) or higher |
| Random glucose with symptoms | — | — | 11.1 mmol/L (200 mg/dL) or higher |
*WHO uses 6.1–6.9 mmol/L (110–125 mg/dL) for impaired fasting glucose; the American Diabetes Association uses 5.6–6.9. Diagnosis usually needs a repeat test unless symptoms are clear.
Typical targets for people with diabetes
| Time | Common target |
|---|---|
| Before meals | 4–7 mmol/L (about 80–130 mg/dL) |
| 1–2 hours after meals | Below 8.5–10 mmol/L (below 180 mg/dL) |
| HbA1c | Often around 48–53 mmol/mol (6.5–7%), individualised |
Targets vary with age, pregnancy, hypoglycaemia risk and other conditions. Follow the targets your care team sets.
Low blood sugar (hypoglycaemia)
- Below 4.0 mmol/L (70 mg/dL) is low and should be treated in people with diabetes
- Below 3.0 mmol/L (54 mg/dL) is clinically significant
- Symptoms: shaking, sweating, hunger, fast heartbeat, confusion, irritability
- Treat with fast-acting sugar (the 15-15 rule), then recheck
When to seek urgent help
- Blood sugar repeatedly above 15 mmol/L (270 mg/dL) with vomiting, abdominal pain, fast breathing or drowsiness (possible DKA)
- Confusion, seizure or unconsciousness with low blood sugar
- Very high readings with extreme thirst and confusion in older adults (possible HHS)
Converting units
mmol/L × 18 = mg/dL. For example, 7 mmol/L ≈ 126 mg/dL.
Frequently asked questions
What is a normal blood sugar after eating?
In people without diabetes, it usually stays below 7.8 mmol/L (140 mg/dL) two hours after a meal.
Is 6.0 mmol/L fasting normal?
It is slightly above normal by ADA criteria (prediabetes range) but below WHO’s 6.1 cut-off. A repeat test and HbA1c help clarify.
Related reading: Hypoglycaemia treatment · How to check blood glucose · Diabetes diet
Based on WHO and American Diabetes Association criteria. Updated 5 November 2026.
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