Fasting blood sugar
- Normal: under 100 mg/dL (5.6 mmol/L)
- Prediabetes: 100–125 mg/dL (5.6–6.9 mmol/L)
- Diabetes: 126 mg/dL (7.0 mmol/L) or above
“Fasting” means no food for at least 8 hours.
After meals (postprandial)
Blood sugar naturally rises after eating. In people without diabetes it usually stays under 140 mg/dL (7.8 mmol/L) two hours after a meal, then settles back down. Targets for people with diabetes are set individually by their care team.
HbA1c — the 3-month average
HbA1c reflects your average glucose over about 2–3 months. Under 5.7% (39 mmol/mol) is normal; 5.7–6.4% (42–47) is prediabetes; 6.5% (48) or above indicates diabetes. It doesn’t need fasting.
When to get checked
See your clinician if readings fall in the prediabetes or diabetes range, or if you have symptoms like increased thirst, frequent urination or unexplained tiredness. Catching raised glucose early gives the best chance to act.