How the conversion works
The US, India and several other countries report blood glucose in mg/dL. The UK, Canada, Australia and most of Europe use mmol/L. To convert, divide mg/dL by 18, or multiply mmol/L by 18. So 126 mg/dL is 7.0 mmol/L.
Normal, prediabetes and diabetes ranges
These are the diagnostic cut-offs listed by the American Diabetes Association:
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting glucose | Below 100 mg/dL (5.6 mmol/L) | 100 to 125 mg/dL (5.6 to 6.9) | 126 mg/dL (7.0) or higher |
| 2 hours after a 75 g glucose drink | Below 140 mg/dL (7.8) | 140 to 199 mg/dL (7.8 to 11.0) | 200 mg/dL (11.1) or higher |
| HbA1c | Below 5.7% | 5.7 to 6.4% | 6.5% or higher |
Some countries draw the prediabetes line a little higher. In the UK it’s an HbA1c of 6.0 to 6.4% (42 to 47 mmol/mol). The diabetes cut-off of 6.5% (48 mmol/mol) is the same everywhere.
HbA1c and average glucose
HbA1c shows how much glucose has stuck to your red blood cells over roughly the last two to three months. The converter uses the formula from the ADAG study: estimated average glucose (mg/dL) = 28.7 x HbA1c – 46.7. An HbA1c of 7% works out to about 154 mg/dL (8.6 mmol/L). It’s an estimate: anaemia, kidney disease, pregnancy and some haemoglobin variants can make HbA1c read higher or lower than your true average.
For more on which test tells you what, see HbA1c vs fasting blood sugar and prediabetes signs and how to reverse it.
Get medical help if
- Your reading is below 70 mg/dL (3.9 mmol/L) with shakiness, sweating or confusion: take fast-acting sugar and recheck in 15 minutes.
- Your reading stays above 300 mg/dL (16.7 mmol/L), or you have high sugar with vomiting, deep fast breathing or drowsiness. Call your local emergency number (911 in the US, 999 in the UK, 112 in the EU and India).
- A fasting result is 126 mg/dL (7.0 mmol/L) or more, or an HbA1c is 6.5% or more: book a doctor’s appointment to confirm.
Frequently asked questions
What is 5.5 mmol/L in mg/dL?
About 99 mg/dL, which is a normal fasting level.
What is 200 mg/dL in mmol/L?
About 11.1 mmol/L.
Is HbA1c the same as average blood sugar?
Not exactly. It’s a percentage that reflects your average over two to three months, and the converter turns it into an estimated average in glucose units.
These tools give general estimates for adults and are not a diagnosis or a substitute for advice from a doctor. If you have symptoms or a health condition, please consult a qualified healthcare professional.