What fasting blood glucose criterion indicates diabetes?

• A. Above 100 mg/dL on one occasion
• B. Above 126 mg/dL on two occasions.
• C. Above 140 mg/dL on one occasion
• D. Above 200 mg/dL on two occasions

Answer: (B)

Diagnosing diabetes with fasting blood glucose relies on showing persistent elevation after an overnight fast. If the fasting plasma glucose is 126 mg/dL or higher on two separate occasions, that confirms diabetes because it demonstrates sustained hyperglycemia rather than a one-time spike. Fasting means no caloric intake for at least 8 hours. Values between 100 and 125 mg/dL are impaired fasting glucose (pre‑diabetes), not diabetes. A single reading above 126 mg/dL isn’t enough—the abnormal result must be repeated on a different day to rule out temporary factors or lab error. Other ways to diagnose diabetes include a 2-hour plasma glucose ≥200 mg/dL after an oral glucose tolerance test or an HbA1c ≥6.5%, or a random glucose ≥200 mg/dL with classic symptoms, but those scenarios involve different testing conditions.