Typical reference ranges
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting (8+ hours) | Below 100 mg/dL (5.6 mmol/L) | 100–125 mg/dL (5.6–6.9) | 126 mg/dL (7.0) or higher |
| 2 hours after 75 g glucose (OGTT) | Below 140 mg/dL (7.8 mmol/L) | 140–199 mg/dL (7.8–11.0) | 200 mg/dL (11.1) or higher |
| Random | Usually below 140 mg/dL | — | 200 mg/dL (11.1) or higher with symptoms |
Ranges based on: MedlinePlus; American Diabetes Association; WHO. Full references are listed at the end of this page.
Use your own lab's range. Reference ranges differ between labs, analysers and methods, and with age, sex and pregnancy. The range printed on your report takes priority over the figures here.
Check your value
Type the Fasting glucose result from your report to see where it sits against the typical ranges on this page. Nothing is sent or saved.
General information only, not a diagnosis. Your lab's printed range takes priority.
Blood Sugar Converter
Convert glucose between mg/dL and mmol/L with normal ranges.
HbA1c Calculator
HbA1c % ↔ mmol/mol and estimated average glucose (eAG).
Types of blood sugar test
- Fasting blood sugar (FBS): after at least 8 hours without food or sugary drinks. Water is fine.
- Random blood sugar (RBS): at any time. Useful when symptoms are present.
- Oral glucose tolerance test (OGTT): fasting sample, then a 75 g glucose drink and a second sample at 2 hours. Used for pregnancy screening and borderline results.
- 2-hour after-meal (post-prandial) sugar: common in South Asia; less standardised than the OGTT.
The WHO and ADA differ slightly
The WHO sets impaired fasting glucose at 110–125 mg/dL (6.1–6.9 mmol/L), while the ADA starts at 100 mg/dL (5.6). The diabetes cut-offs are the same.
Low blood sugar
Below 70 mg/dL (3.9 mmol/L) is low (hypoglycaemia), and below 54 mg/dL (3.0 mmol/L) is clinically significant. It mostly happens in people taking insulin or sulfonylureas. Symptoms include shaking, sweating, hunger, confusion and, if severe, fits or loss of consciousness.
Units
The US and South Asia use mg/dL; the UK, Europe and much of the Gulf use mmol/L. Divide mg/dL by 18 to get mmol/L. The blood sugar converter on this site does it instantly.
Frequently asked questions
What is normal blood sugar after eating?
Usually below 140 mg/dL (7.8 mmol/L) two hours after a meal in people without diabetes.
Can I drink water before a fasting sugar test?
Yes. Plain water is fine; avoid tea, coffee and juice.
Is a fasting sugar of 110 normal?
It is in the prediabetes range by ADA criteria and at the WHO threshold for impaired fasting glucose.
How do I convert mg/dL to mmol/L?
Divide by 18. 126 mg/dL ÷ 18 = 7.0 mmol/L.