Metformin Use in Prediabetes Among U.S. Adults, 2005–2012

OBJECTIVE To determine the prevalence of and characteristics associated with metformin use among U.S. adults with prediabetes using the National Health and Nutrition Examination Survey (NHANES) 2005–2012. RESEARCH DESIGN AND METHODS The American Diabetes Association’s guidelines for metformin use in prediabetes have evolved, with 2017 recommendations suggesting metformin be considered in patients with prediabetes and additional risk factors (BMI ≥35 kg/m2, age <60 years, or prior gestational diabetes mellitus) or rising hemoglobin A1c (HbA1c). We estimated the age-adjusted prevalence of metformin use among individuals with prediabetes (defined by HbA1c 5.7–6.4%, fasting glucose 100–125 mg/dL, 2-h poststimulated glucose 140–199 mg/dL, or self-report) and used multivariate logistic regression to evaluate characteristics associated with metformin use. RESULTS Of 22,174 adults, 7,652 had prediabetes. The age-adjusted prevalence of metformin use among those with prediabetes was 0.7%. Metformin use was associated with higher mean BMI (35.1 kg/m2 vs. 29.6 kg/m2, P < 0.01) and higher glucose (fasting glucose 114 mg/dL vs. 105 mg/dL, P = 0.03; 2-h poststimulated glucose 155 mg/dL vs. 128 mg/dL, P = 0.003; and HbA1c 6.0% [42 mmol/mmol] vs. 5.6% [38 mmol/mmol], P < 0.01). Metformin use was low even among those with BMI ≥35 kg/m2, a group for whom metformin use is recommended. Metformin use did not vary by race, poverty-to-income ratio, or education. CONCLUSIONS Metformin use was <1% among U.S. adults with prediabetes and only slightly more common among those with additional risk factors for diabetes.