Less than 4% of adults with prediabetes are prescribed metformin for diabetes prevention, despite the fact that the condition affects one in three Americans, researchers said.

A 3-year retrospective cohort analysis of health insurance data from 17,352 working-age adults with prediabetes showed that only 3.7% had a prescription claim for metformin, although that figure rose to 7.8% among the subset of patients with a body mass index greater than 35 kg/m2 or those with gestational diabetes.

Dr. Tannaz Moin and her associates defined prediabetes as either a hemoglobin A1c level of 5.7% to 6.4%, a fasting plasma glucose level of 5.55 to 6.94 mmol/L (100-125 mg/dL), or a 2-hour plasma glucose level of 7.77 to 11.04 mmol/L (140-199 mg/dL) on an oral glucose tolerance test.

Women were almost twice as likely to receive a metformin prescription as were men (4.8% versus 2.8%), while obese individuals and those with two or more comorbid conditions also were more likely to be prescribed metformin, according to findings published in the Annals of Internal Medicine (Ann. Intern. Med. 2015;162:542-8).

“Our findings indicate that metformin is rarely prescribed for diabetes prevention despite a strong evidence base in the literature for more than 10 years and inclusion in practice guidelines for more than 6 years,” wrote Dr. Moin of the University of California, Los Angeles, and her associates. “This is a potential gap in the approach to prediabetes management and a significant missed opportunity for diabetes prevention in patients at highest risk.”

The study was funded by the Centers for Disease Control and Prevention and the National Institute of Diabetes and Digestive and Kidney Diseases. One of the study authors was an employee of UnitedHealthcare.