Which of the following patients meets the diagnostic criteria for diabetes mellitus according to the American Diabetes Association?

• A. Fasting glucose 100 mg/dL and an A1C of 5.5%
• B. Polyuria, polydipsia, and a random glucose of 240 mg/dL
• C. Asymptomatic fasting glucose 136 mg/dL (day 1) and 110 mg/dL (day 2)
• D. Asymptomatic random glucose 220 mg/dL

Answer: (B)

The important idea is that diabetes is diagnosed by clear evidence of sustained hyperglycemia, using one of several criteria. One key route is having classic symptoms of high blood sugar (such as excessive urination and thirst) plus a random glucose value that meets the diagnostic threshold. When both are present, diabetes can be diagnosed without needing a second test.

In this scenario, the patient has classic hyperglycemia symptoms and a random glucose that surpasses the diagnostic threshold, so this finding confirms diabetes.

The other scenarios don’t meet the criteria: one patient has normal fasting glucose and a normal A1C, so there’s no evidence of diabetes. Another shows a single high fasting value but a second day isn’t elevated, so there isn’t two abnormal fasting measurements. The last patient is asymptomatic with a high random glucose, which doesn’t confirm diabetes without symptoms or an additional confirmatory test.