medwireNews: Fifteen years of follow-up of the DPP trial shows that although people initially lost more weight with the intensive lifestyle intervention, those assigned to metformin did better at keeping the weight off in the long term.
However, the amount of weight lost during the first year of the trial predicted long-term success irrespective of how people achieved the initial reduction. Older age was also a predictive factor for long-term weight loss maintenance.
Kishore Gadde (The George Washington University Biostatistics Center, Rockville, Maryland, USA) and team studied DPP participants, all with elevated glucose levels and overweight or obesity, who had lost at least 5% of their bodyweight during the first year of the trial and remained in follow-up until year 15 of the outcomes study.
Although people undertaking the lifestyle intervention had the greatest initial success, with 62.6% losing 5% of their bodyweight, only 48.9% of 373 participants remaining in the study until year 15 maintained this for the entire follow-up.
But the researchers note that “despite significant weight regain,” the average long-term weight loss of 3.7% with the lifestyle intervention is important from a population health perspective, because of the increasing use of diabetes prevention programs.
In the metformin group, only 28.5% achieved the 5% weight loss goal, but 56.5% of the 172 people followed up to year 15 maintained it consistently. The corresponding values in the placebo group (92 participants by year 15) were 13.4% and 41.7%.
Among people assigned to metformin, active use of the study medication increased the likelihood of maintaining initial weight loss 2.17-fold at year 15, the research team reports in the Annals of Internal Medicine.
Their chances of long-term success were also significantly increased with each 10-year increase in baseline age and each 5% greater weight loss, with the same being true in the lifestyle intervention group.
In a linked editorial, Leslie Katzel and John Sorkin, both from the University of Maryland School of Medicine in Baltimore, USA, note that the DPP cannot address whether lifestyle intervention or metformin is better in the long term, and whether the two combined might have even larger benefits.
“It might make sense to begin with an [intensive lifestyle intervention] because this resulted in the greatest weight loss and had the greatest effect on preventing progression to diabetes,” they suggest.
Katzel and Sorkin say that “[f]or now, clinical judgment should be used to decide whether metformin should be added if [the lifestyle intervention] does not succeed or if the patient subsequently regains the weight they lost.”
But they add that ongoing studies looking at the effect of metformin on other outcomes, such as cardiovascular disease and cancer, may inform clinical decision-making.
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