How Does Metformin Prevent Insulin-associated Weight Gain?

February 1, 2018

One theory is that metformin taken during insulin treatment impacts energy intake and so supports weight loss. A quick look at a new study suggests something else.

There is evidence that patients who take metformin while being treated with insulin for type 2 diabetes are not subject to the the traditional weight gain seen with insulin treatment. One hypothesis is that metformin has an effect on patients' energy intake. The short slide show above offers highlights of recent study that came to a very different conclusion.Source:Â Out M, Miedema I, Jager-Wittenaar H, et al. Metformin-associated prevention of weight gain in insulin-treated type 2 diabetic patients cannot be explained by decreased energy intake: A post hoc analysis of a randomized placebo-controlled 4.3-year trial. Diabetes Obes Metab. 2018;20:219â223.Â

Metformin prevents insulin-associated weight gain, but how?

How Does Metformin Do It? Small studies have shown that metformin prevents weight gain in T2D patients; one possible mechanism is a metformin effect on patients' energy intake.

Insulin + MET or Placebo. T2D patients assigned to insulin plus metformin or placebo. At 4.3 years of follow-up, no significant difference in energy intake found between groups; weight gain higher in placebo group vs metformin group.

MET Attenuates Insulin Use. Analysis showed use of MET reduced insulin requirements, preventing insulin-triggered weight gain. Insulin-associated weight gain may be caused by a number of different mechanisms

MET Metabolic Effects. Among other effects that support weight loss, metformin may behave as an incretin mimetic, enhancer, and sensitizer, increasing bioavailability & efficacy of glucagon-like peptide-1 (GLP-1).

Authors' Conclusions. The important take-home is that Approximately one-third of the difference in weight gain between metformin and placebo recipients can be explained by the reduction of insulin requirements by use of metformin.