Knowing what "normal" looks like is the first step toward managing blood sugar. Here are the numbers most clinicians use.
Fasting blood sugar (no food for 8+ hours)
- 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 higher on two separate tests
2 hours after a meal
- Normal: under 140 mg/dL (7.8 mmol/L)
- Prediabetes: 140–199 mg/dL (7.8–11.0 mmol/L)
- Diabetes: 200 mg/dL (11.1 mmol/L) or higher
HbA1c (3-month average)
- Normal: below 5.7%
- Prediabetes: 5.7%–6.4%
- Diabetes: 6.5% or higher
Why post-meal numbers matter most
Fasting glucose is only one snapshot. Post-meal spikes are what damage blood vessels over time. A CGM or finger-stick test 1–2 hours after eating gives you a far better picture of your real glycemic health.
When to retest
If a single reading is off, retest before panicking. Stress, illness, dehydration, poor sleep and even strong coffee can shift glucose by 20–40 mg/dL temporarily.