A fasting plasma glucose level of 152 mg/dL is most consistent with which condition?

• A. Primary adrenal insufficiency
• B. Impaired glucose tolerance
• C. Diabetes mellitus
• D. Cushing's syndrome

Answer: (C)

Fasting plasma glucose is measured after at least 8 hours without eating. Diabetes mellitus is diagnosed when fasting glucose is 126 mg/dL or higher, typically confirmed on a second test. A value of 152 mg/dL clearly exceeds that threshold, making diabetes the most consistent interpretation.

Impaired glucose tolerance is determined by the 2-hour glucose value after a 75 g oral glucose tolerance test, not by a fasting level. Primary adrenal insufficiency and Cushing's syndrome can affect glucose metabolism and may lead to hyperglycemia, but they are not diagnosed from a single fasting glucose reading; they require additional clinical clues and testing.