The fasting plasma glucose threshold for diagnosing diabetes mellitus is what value?

• A. 126 mg/dL or higher on two occasions
• B. 100 mg/dL or higher
• C. 140 mg/dL or higher
• D. 200 mg/dL or higher

Answer: (A)

Diagnosing diabetes relies on established glycemic thresholds and the need for confirmation to avoid misclassification. For fasting plasma glucose, a level of 126 mg/dL or higher, when documented on two separate occasions, confirms diabetes. Values between 100 and 125 mg/dL are considered impaired fasting glucose (prediabetes), not diabetes. In an oral glucose tolerance test, a 2-hour value of 140–199 mg/dL indicates impaired glucose tolerance, while 200 mg/dL or higher confirms diabetes. So the correct threshold for diagnosing diabetes with fasting glucose is 126 mg/dL or higher on two separate tests.