Metformin medication not protective against age-related macular degeneration

Treatment with metformin, along with lifestyle changes, initiated for the prevention of diabetes does not appear to reduce the risk of age-related macular degeneration (AMD), a study has found.

The study used data from the Diabetes Prevention Program Outcomes Study, a cross-sectional follow-up phase of a large multicentre randomized clinical trial aimed at investigating the association of metformin treatment or an intensive lifestyle modification vs placebo with prevention of type 2 diabetes in a high-risk population.

A total of 1,592 participants with retinal imaging at a follow-up visit 16 years after the trial were included in the analysis. Of these, 514 (32.3 percent) participants were in the lifestyle arm, 549 (34.5 percent) were in the metformin arm, and 529 (33.2 percent) were in the placebo arm. The participants across the three intervention arms had comparable baseline characteristics, including age (mean age at randomization 49 years), sex (71 percent male), race and ethnicity (49 percent White), smoking habits, body mass index, and education level.

Overall, 479 (30.1 percent) participants had AMD, with 229 (14.4 percent) having early AMD, 218 (13.7 percent) having intermediate AMD, and 32 (2.0 percent) having advanced AMD. The proportion of participants with AMD was similar across the three intervention arms: 152 (29.6 percent) in the lifestyle arm, 165 (30.2 percent) in the metformin arm, and 162 (30.7 percent) in the placebo arm. Likewise, there was no significant difference in the distribution of early, intermediate, and advanced AMD.

In the metformin arm, the mean duration of treatment did not differ between participants with and without AMD (mean, 8.0 vs 8.5 years; p=0.69).

Multivariate logistic regression analysis revealed history of smoking as a risk factor for AMD (odds ratio, 1.30, 95 percent CI, 1.05–1.61; p=0.02).