Metformin May Help Patients Maintain Weight Loss Long-Term

By Reuters Staff

NEW YORK (Reuters Health) - For overweight adults who successfully lose weight with diet and exercise, metformin can help them keep the pounds off long-term, according to new data from the diabetes prevention program (DPP) clinical trial and its long-term outcomes study (DPPOS) online today in Annals of Internal Medicine.

The DPP was a randomized controlled trial that compared weight loss and diabetes prevention with metformin, intensive lifestyle intervention (ILS), or placebo in 3,234 overweight or obese adults with prediabetes. A total of 1,066 participants lost at least 5% of their baseline weight in the first year and were followed for 15 years in the DPPOS after the masked treatment phase ended.

In the first year, roughly twice as many people in the ILS group as the metformin group lost at least 5% of their body weight (63% vs 29%), but those in the metformin group had greater success at keeping the weight off between years six and 15. Ultimately, 6.2% of patients on metformin kept the weight off compared with 3.7% of those in the ILS group.

Being older and losing a greater amount of weight in the first year were the most consistent predictors of lasting weight loss, report Dr. Kishore Gadde from The George Washington University Biostatistics Center in Rockville, Maryland and colleagues. The cumulative incidence of diabetes over 15 years was lower among those who lost at least 5% of their weight in the first year.

The authors say more study is needed to see whether metformin could be a useful intervention for weight loss maintenance after initial weight loss with lifestyle interventions, antiobesity drugs or devices, or bariatric surgery.

"A major finding from the DPP and the DPPOS is that modest weight loss decreases risk for progression to diabetes. Thus, although (long-term weight loss) LTWL is not likely to be universally achievable, it makes sense to help patients strive for it," Drs. Leslie Katzel and John Sorkin from the University of Maryland School of Medicine in Baltimore write in a linked editorial.

The current study, however, can't answer the question of which therapy is better over the long-term, they note. "It might make sense to begin with an ILS because this resulted in the greatest weight loss and had the greatest effect on preventing progression to diabetes. Unfortunately, the DPP did not include a combined ILS and metformin group, so we do not know whether the 2 interventions are synergistic, particularly for initial weight loss. For now, clinical judgment should be used to decide whether metformin should be added if ILS does not succeed or if the patient subsequently regains the weight they lost," Drs. Katzel and Sorkin suggest.

They note that the DPPOS-3 is following participants for another five years, with the primary outcome measures of the long-term effects of metformin on cardiovascular disease and cancer. In addition to DPPOS-3, more than 10 clinical trials are looking at the effect of metformin on various outcomes. "If these studies show that metformin has the additional salutary effects that have been posited, the magnitude of these effects will have to be part of the decision-making process in choosing the best intervention for promotion of LTWL," the editorial writers conclude.

SOURCE: https://bit.ly/2ve1Za7 and https://bit.ly/2vjhFZv

Ann Intern Med 2019.

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