Madison, WI—While inconclusive, some retrospective studies have raised the possibility that metformin, the first-line medication for the treatment of type 2 diabetes, could have a role in the treatment of age-related macular degeneration (AMD) and might even be protective against the progression to late AMD.
Despite the hopes raised by those electronic medical records data reviews, a new study did not find any association with the use of metformin and the prevalence of AMD, however.
Published in JAMA Ophthalmology, the cross-sectional study was a follow-up phase of a randomized clinical trial for the prevention of diabetes. The conclusions were based on the evaluation of retinal photographs 16 years post trial from 549 participants taking metformin, 514 undergoing lifestyle intervention, and 512 in the placebo arm.
“Long-term use of metformin and lifestyle intervention may not be associated with development of AMD,” write the authors from the University of Wisconsin and their colleagues.
AMD is a leading cause of blindness with no treatment available for early stages.
The Diabetes Prevention Program Outcomes Study is a cross-sectional follow-up phase of a large multicenter, randomized clinical trial, Diabetes Prevention Program (1996-2001). It is investigating the association of treatment with metformin or an intensive lifestyle modification versus placebo in preventing type 2 diabetes in a population at high risk for developing diabetes.
For this analysis, participants with retinal imaging at a follow-up visit 16 years post trial (2017-2019) were included. Analysis took place between October 2019 and May 2022. The participants were randomly distributed between three interventional arms: lifestyle, metformin, and placebo.
Of 1,592 participants, 514 (32.3%) were in the lifestyle arm, 549 (34.5%) were in the metformin arm, and 529 (33.2%) were in the placebo arm, with the groups balanced for baseline characteristics including age (mean [SD] age at randomization, 49 [9] years), sex (1,128 [71%] male), race and ethnicity (784 [49%] white), smoking habits, body mass index, and education level.
The study team identified AMD in 479 participants (30.1%); of those, 229 (14.4%) had early AMD, 218 (13.7%) had intermediate AMD, and 32 (2.0%) had advanced AMD.
Researchers found no significant difference in the presence of AMD between the three groups:
• 152 (29.6%) in the lifestyle arm,
• 165 (30.2%) in the metformin arm, and
• 162 (30.7%) in the placebo arm.
In addition, no differences in the distribution of early, intermediate, and advanced AMD were detected among the intervention groups. Researchers point out that mean duration of metformin use was similar for those with and without AMD (mean [SD], 8.0 [9.3] vs. 8.5 [9.3] years; P = .69). On the other hand, in the multivariate models, history of smoking was associated with increased risks of AMD (odds ratio, 1.30; 95% CI, 1.05-1.61; P = .02).
“These data suggest neither metformin nor lifestyle changes initiated for diabetes prevention were associated with the risk of any AMD, with similar results for AMD severity,” the authors explain. “Duration of metformin use was also not associated with AMD. This analysis does not address the association of metformin with incidence or progression of AMD.”
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