Prolonged metformin use effective for Type 2 diabetes, study finds

PORTLAND, Ore. The sooner people with diabetes start taking metformin, the longer the drug remains effective, according to a Kaiser Permanente study published in the March issue of Diabetes Care, a journal of the American Diabetes Association.

Metformin is recommended as a first-line agent in the treatment of Type 2 diabetes, but its efficacy may deplete among patients. To determine how the drug influences patients' control of their diabetes, researchers attained electronic health records to follow nearly 1,800 people with diabetes in Kaiser Permanente's health plan in Washington and Oregon for up to five years. Metformin failed at a rate of only 12% a year for the patients who began taking it within three months of diagnosis, compare with a failure rate of 21.4% per year for patients who started taking metformin one to two years after diagnosis, and 21.9% per year for those who didn't start taking the drug until three years after they were diagnosed.

In the study, patients were considered to have failed metformin when their hemoglobin A1C -- a test that monitors glucose control --- went above 7.5% or when they started taking a second anti-hyperglycemic agent. Only patients who initially controlled blood sugar (to less than 7% on the A1C test) with metformin were included in the study.

Study authors Jonathan Brown, PhD, MPP, and Gregory Nichols, PhD, from the Kaiser Permanente Center for Health Research in Portland, Ore., and Christopher Conner, PharmD, PhD, from Novo Nordisk, said the results of the study were welcomed news for newly diagnosed patients.

"This is an important finding for the 30 million people world-wide who are diagnosed with Type 2 diabetes every year. The sooner they start taking metformin, the better and longer it seems to work," said the study's lead author Brown said. "This study suggests that to gain full benefit from metformin, patients should start taking it as soon as they find out they have diabetes."