MKSAP Quiz: Treatment plan for prediabetes

This month's quiz asks readers to evaluate a 68-year-old woman with a fasting plasma glucose level of 113 mg/dL.

A 68-year-old woman is re-evaluated after laboratory studies show a fasting plasma glucose level of 113 mg/dL (6.3 mmol/L). She has a maternal family history of type 2 diabetes mellitus.

On physical examination, blood pressure is 142/88 mm Hg and BMI is 29. Other vital signs and examination findings are normal.

She undergoes an oral glucose tolerance test, during which her 2-hour plasma glucose level increases to 135 mg/dL (7.5 mmol/L).

Additional laboratory studies:

Hemoglobin A1c 5.8%
LDL cholesterol 110 mg/dL (2.85 mmol/L)
HDL cholesterol 48 mg/dL (1.24 mmol/L)
Triglyceride 172 mg/dL (1.94 mmol/L)

Which of the following is the most appropriate treatment recommendation to control her glucose level?

A. Acarbose administration
B. Diet and exercise
C. Metformin administration
D. Ramipril administration
E. Rosiglitazone administration

MKSAP Answer and Critique

The correct answer is B. Diet and exercise. This item is available to MKSAP 15 subscribers as item 21 in the Endocrinology section. Part A of MKSAP 16 will be released on July 31. More information is available online.

This patient with impaired fasting glucose (IFG), defined as a fasting plasma glucose level in the range of 100 to 125 mg/dL (5.6 to 6.9 mmol/L), should begin a program of intensive lifestyle change, including 30 minutes of exercise most days of the week and a calorie-restricted diet, to achieve weight reduction on the order of 7% of body weight.

According to a consensus statement on the prevention of diabetes from the American Diabetes Association and the European Association for the Study of Diabetes, diet and exercise is the recommended approach for patients with either IFG or impaired glucose tolerance (IGT), the prediabetic states. In the Diabetes Prevention Program (DPP), the relative risk reduction (RRR) in the incidence of diabetes in patients with IGT who were assigned to intensive lifestyle change was 58%.

Pharmacologic therapy with glucose-lowering drugs is not indicated for this patient with isolated IFG. In pharmacologic studies of diabetes prevention, acarbose therapy resulted in only a 25% RRR, which is inferior to that obtained with diet and exercise.

Metformin therapy is associated with a RRR of 31%, which is also inferior to the 58% RRR obtained with diet and exercise. The consensus panel has recommended that metformin therapy be considered in patients with both IFG and IGT, who constitute a higher risk group. This patient does not have IGT (fasting plasma glucose level of 140 to 199 mg/dL [7.7 to 11.0 mmol/L] at the 2-hour mark of an oral glucose tolerance test) and so should not receive metformin.

Modulators of the renin-angiotensin axis, such as ramipril and other angiotensin-converting enzyme inhibitors, were once thought to contribute to diabetes prevention, but the Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication (DREAM) study disproved this.

Rosiglitazone and pioglitazone have been associated, respectively, with 62% and 81% RRRs in the incidence of diabetes. However, the consensus panel has not endorsed their routine pharmacologic use in patients with prediabetes because of their costs and adverse effects, including edema, increased fracture risk in women, and possible increased cardiovascular morbidity.

Key Point

  • Patients with prediabetes should be advised to adopt a program of lifestyle change to prevent progression to type 2 diabetes mellitus.