Individuals at risk for developing type 2 diabetes who are prescribed the drug metformin should stick with it, doctors say. In a large study, individuals who adhered to a metformin-based diabetes preventive strategy had a reduced risk of developing diabetes, they report.

The Diabetes Prevention Program (DPP) investigated the value of intensive lifestyle intervention (diet and exercise) or metformin in delaying or preventing type 2 diabetes in high-risk individuals with impaired glucose tolerance, a precursor to full-blown diabetes.

Dr. Elizabeth A. Walker, of George Washington University, Rockville, Maryland, and colleagues examined medication adherence and health outcomes in the metformin and placebo arms of the DPP.

A total of 2155 subjects who were randomly assigned to either the metformin or placebo treatment arms were included in the analysis.

The overall adherence rates - that is, the proportion of patients taking at least 80 percent of the prescribed dose - were 71 percent in the metformin group and 77 percent in the placebo group.

Compared to patients who were adherent to placebo, those adherent to metformin had a 38.2 percent reduced risk of developing diabetes, the investigators report. In this study, “the level of medication adherence predicted the primary outcome of diabetes,” they write in the journal Diabetes Care.

Among patients taking metformin, older subjects were more adherent than younger subjects.

Walker’s team reports that the most commonly reported barriers to taking the medication as prescribed were forgetting to take doses (22 percent), adverse effects (8 percent), and disruption of routines (8 percent). Overall, 15 percent of women and 10 percent of men reported adverse effects in the metformin group.

These results, the team concludes, “lend support for future development and evaluation of brief, practical medication adherence interventions for primary care settings.”

SOURCE: Diabetes Care, September 2006.