How doctors diagnose diabetes and prediabetes
How do you diagnose diabetes and prediabetes?
By testing your blood glucose (sugar) and HbA1C levels. The haemoglobin A1C test (HbA1C) measures your average blood sugar level over the last 2-3 months. This test doesn’t require fasting and can be done any time.
Blood glucose in prediabetes and diabetes
- Normal human blood sugar = 4-6 mmol/L
- Prediabetes is diagnosed if your random blood sugar = 7-11 mmol/L (twice)
- Diabetes is diagnosed if you have a random blood sugar > 11 mmol/L (or a fasting blood sugar > 7 mmol/L) (twice).
HbA1C in prediabetes and diabetes
- Normal HbA1c = 20-42 mmol/mol (or 4-6%)
- Prediabetes is diagnosed if your HbA1c = 42-47 mmol/L (6-6.5%) (twice)
- Diabetes is diagnosed if your HbA1c = 48 mmol/mol or over (>6.5%).
HbA1C mmol/mol and %
Confusingly HbA1c comes in 2 different units (% is the older unit). These are the equivalent values.
42 mmol/mol = 6.0% = prediabetes
48 = 6.5 = diabetes
53 = 7
59 = 7.5
64 = 8
75 = 9.
Diabetes UK has a converter to convert HbA1C from mmol/mol to %, and vice versa.
Monitoring of DM in adults (and target HbA1Cs)
If you have diabetes, an ideal HbA1c level is 48mmol/mol (6.5%) or below.
Summary
We have explained how the diagnosis of diabetes and prediabetes is made. We have also given normal blood glucose (sugar) and HbA1C levels. We hope it has been helpful.
Other resources
Here is more information on blood glucose, HbA1c and definitions of DM.
