What is the normal fasting blood glucose range for adults?

• A. 60–90 mg/dL
• B. 70–100 mg/dL
• C. 80–110 mg/dL
• D. 90–120 mg/dL

Answer: (B)

Fasting blood glucose measures the level of glucose in the blood after about 8 hours without eating, showing how well insulin and hepatic glucose production are balanced during a baseline state. The normal range for adults is roughly 70 to 100 mg/dL. This range reflects typical insulin action and hepatic glucose output when you’re fasting. Values above 100 mg/dL, especially in the 100–125 mg/dL range, suggest impaired fasting glucose (prediabetes), and a level of 126 mg/dL or higher on two occasions points to diabetes. Values below 70 mg/dL can indicate hypoglycemia and warrant attention. So the 70–100 mg/dL span best represents normal fasting glucose.