It’s cheap, safe, and been proven to be an effective way to both treat and prevent Type 2 diabetes over many decades. Yet a new study finds few doctors are prescribing metformin to those with pre-diabetes who are at risk for developing the metabolic disorder.

Researchers with the University of California-Los Angeles have determined only 3.7 percent of U.S. adults with pre-diabetes are prescribed metformin. The findings, published in the journal Annals of Internal Medicine, many of the 57 million Americans with pre-diabetes are missing out on significant way to stay healthy.

Metformin and lifestyle changes both can prevent the onset of diabetes, but people often struggle to adopt healthier habits, noted lead researcher Tannaz Moin, M.D., an assistant professor of medicine in the division of endocrinology at the David Geffen School of Medicine at UCLA and at VA Greater Los Angeles.

"Diabetes is prevalent, but pre-diabetes is even more prevalent and we have evidence-based therapies like metformin that are very safe and that work," Dr. Moin said. "Metformin is rarely being used for diabetes prevention among people at risk for developing it. This is something that patients and doctors need to be talking about and thinking about."

Pre-diabetes is marked by higher-than-normal blood sugar levels, but not quite in the diabetes range. The American Diabetes Association in 2008 added metformin to its guidelines for use in diabetes prevention for such individuals who are under age 60, are severely obese, or have a history of gestational diabetes.

For the new study, UCLA researchers tracked 17,352 adults aged 19 to 58 with pre-diabetes insured by UnitedHealthcare. They also found:

• The prevalence of metformin prescriptions was 7.8 percent for severely obese patients.
• Metformin prescriptions were nearly twice as high for women (4.8 percent) as for men (2.8 percent).
• Among people with pre-diabetes, the prevalence of prescriptions for obese individuals was 6.6 percent, versus 3.5 percent for non-obese people.
• Among people who had pre-diabetes and two other chronic diseases, 4.2 percent received prescriptions for metformin, versus 2.8 percent of people with pre-diabetes and no other chronic diseases.

The reasons for the underuse of metformin are not clear, but one factor may be a reluctance by patients and doctors to "medicalize" pre-diabetes.

"Identifying more effective ways to help people avoid diabetes is essential to individuals' lives and to society as a whole, which is why it was important to us to support this research," said Sam Ho, M.D., a co-author of the study and chief medical officer of Minnesota-based UnitedHealthcare.