ILLUSTRATIVE CASE
A 51-year-old woman with a history of elevated cholesterol and a body mass index (BMI) of 31 presents to your clinic for a scheduled follow-up visit to review recent blood test results. Her A1C was elevated at 5.9%. She wants to know if she should start medication now.
Prediabetes is a high-risk state that confers increased risk for type 2 diabetes (T2D). It is identified by impaired fasting glucose (fasting plasma glucose [FPG], 100-125 mg/dL), impaired glucose tolerance (2-hour oral glucose tolerance test, 140-199 mg/dL), or an elevated A1C (between 5.7% and 6.4%).2
An estimated 96 million Americans—38% of the US adult population—have prediabetes, according to the Centers for Disease Control and Prevention.3 Family physicians frequently encounter this condition when screening for T2D in asymptomatic adults (ages 35 to 70 years) with overweight or obesity, as recommended by the US Preventive Services Task Force (grade “B”).4
To treat, or not? Studies have shown that interventions such as lifestyle modification and use of metformin by patients with prediabetes can decrease their risk for T2D.5,6 In the Diabetes Prevention Program (DPP) study, progression from prediabetes to T2D was reduced to 14% with lifestyle modification and 22% with metformin use, vs 29% with placebo.7
However, there is disagreement about whether to treat prediabetes, particularly with medication. Some argue that metformin is a safe, effective, and cost-saving treatment to prevent T2D and its associated health consequences.8 The current American Diabetes Association (ADA) guidelines suggest that metformin be considered in certain patients with prediabetes and high-risk factors, especially younger age, obesity or hyperglycemia, or a history of gestational diabetes.9 However, only an estimated 1% to 4% of adults with prediabetes are prescribed metformin.10
Others argue that treating a preclinical condition is not a patient-centered approach, especially since not all patients with prediabetes progress to T2D and the risk for development or progression of retinopathy and microalbuminuria is extremely low if A1C levels remain < 7.0%.11 By this standard, pharmacologic treatment should be initiated only if, or when, a patient develops T2D, with a focus on intensive lifestyle intervention for high-risk patients in the interim.11
Given the conflicting viewpoints, ongoing long-term studies on T2D prevention will help guide treatment decisions for patients with prediabetes. The study by Lee et al1 was the first to evaluate the effect of metformin or intensive lifestyle modification on all-cause and cause-specific mortality in patients at high risk for T2D.
Continue to: STUDY SUMMARY
