How to use this tool
- Choose the unit your meter or report uses.
- Enter the reading and when it was taken.
- Read the converted value and how it compares with the standard ranges.
Why there are two units
mg/dL measures glucose by weight and is used in the US, India, Pakistan and much of the Middle East. mmol/L counts molecules and is used in the UK, Europe, Canada and Australia. Glucose has a molecular weight of about 180 g/mol, which gives the conversion factor of 18.
Glucose ranges
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting | below 100 mg/dL (5.6) | 100–125 (5.6–6.9) | 126+ (7.0+) |
| 2-hour OGTT | below 140 (7.8) | 140–199 (7.8–11.0) | 200+ (11.1+) |
| Random, with symptoms | — | 200+ (11.1+) | |
Values in brackets are mmol/L. The WHO sets impaired fasting glucose at 110–125 mg/dL (6.1–6.9 mmol/L) rather than the ADA's 100. Treatment targets for people already living with diabetes are set individually by their care team.
Frequently asked questions
How do I convert mg/dL to mmol/L?
Divide by 18. 126 mg/dL ÷ 18 = 7.0 mmol/L.
What is normal fasting blood sugar?
Below 100 mg/dL (5.6 mmol/L).
Is 140 mg/dL after eating normal?
Two hours after eating, below 140 mg/dL (7.8 mmol/L) is normal.
What blood sugar is too low?
Below 70 mg/dL (3.9 mmol/L) is hypoglycaemia.
Sources and references
- American Diabetes Association: Diagnosis
- WHO: Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia (2006)
- NHS: Blood sugar levels and testing