MKSAP quiz: Screening for diabetes

This month's quiz asks readers to consider a 38-year-old man who expresses interest in being screened for diabetes during a periodic health maintenance visit.

A 38-year-old man is evaluated during a periodic health maintenance visit. His friend was recently diagnosed with type 2 diabetes mellitus, and the patient expresses interest in being screened. He is asymptomatic and reports no symptoms of polyuria or polydipsia. He exercises regularly. Medical and family histories are unremarkable. He takes no medications.

On physical examination, the patient is afebrile, and blood pressure is 126/72 mm Hg. BMI is 28. The remainder of the examination is normal.

Laboratory studies reveal an LDL cholesterol level of 97 mg/dL (2.51 mmol/L) and an HDL cholesterol level of 55 mg/dL (1.42 mmol/L).

According to U.S. Preventive Services Task Force recommendations, when should this patient be screened for type 2 diabetes?

A. At a BMI of 30
B. At age 40 years
C. At age 50 years
D. At the current visit

MKSAP Answer and Critique

The correct answer is B. At age 40 years. This item is available to MKSAP 17 Digital and Complete subscribers as item 6 in the General Internal Medicine section of Update 2. More information about MKSAP 17 is available online.

This patient should be screened for abnormal blood glucose and type 2 diabetes mellitus at age 40 years. In a 2015 recommendation statement, the U.S. Preventive Services Task Force (USPSTF) recommended screening for abnormal blood glucose as part of cardiovascular risk assessment in all adults aged 40 to 70 years who are overweight (BMI 25-29.9) or obese (BMI >30). The evidence for the optimal screening frequency is limited, but the USPSTF suggests screening every 3 years. Screening can be performed with measurement of fasting plasma glucose or HbA1c or with an oral glucose tolerance test. Patients with evidence of abnormal glucose metabolism should be referred for intensive behavioral counseling interventions aimed at promoting a healthful diet and physical activity. Behavioral counseling in this population has been shown to have a moderate impact on incidence of diabetes and cardiovascular outcomes. This patient has a BMI of 28, so he meets the criterion for overweight; however, he is not yet 40 years old. He should be screened in 2 years if his BMI remains above 25.

The screening initiation age and frequency are the same for both overweight and obese patients according to the USPSTF recommendation. In a patient age 40 years or older, it would be inappropriate to delay screening until BMI reaches 30.

Key Point

  • The U.S. Preventive Services Task Force recommends screening all adults aged 40 to 70 years who are overweight or obese for abnormal blood glucose and type 2 diabetes mellitus.