Metformin use in prediabetes among U.S. adults, 2005-2012

Objective: To determine the prevalence of and characteristics associatedwithmetformin 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 diabetesmellitus) or rising hemoglobin A_1c (HbA_1c).We estimated the age-adjusted prevalence of metformin use among individuals with prediabetes (defined by HbA_1c 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 HbA_1c 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.