Normal fasting blood sugar—measured after at least 8 hours without food or drink except water—typically ranges from 70 to 100 mg/dL (3.9 to 5.6 mmol/L) for people without diabetes. This measurement is called fasting glucose or fasting blood sugar (FBS).
A fasting blood sugar reading between 100 and 125 mg/dL is often considered impaired fasting glucose, which may indicate prediabetes. A reading of 126 mg/dL or higher, confirmed on a separate test, can indicate diabetes.
For people with diabetes, target fasting blood sugar ranges are often set individually by healthcare providers, but commonly aim for 80 to 130 mg/dL. These targets may differ based on age, other health conditions, and individual treatment plans.
Blood sugar naturally rises after eating regardless of diabetes status. The postprandial (after-eating) blood sugar for non-diabetic people typically rises to below 140 mg/dL two hours after meals. In people with diabetes, healthcare providers may set different postprandial targets.
Variations in fasting blood sugar can result from stress, illness, certain medications, sleep quality, and physical activity levels. For accurate assessment, multiple readings over time are generally more informative than a single measurement. Anyone concerned about their blood sugar levels should consult a healthcare provider for personalized guidance.