Association of Metformin With the Development of Age-Related Macular Degeneration

Importance

Age-related macular degeneration (AMD) is a leading cause of blindness with no treatment available for early stages. Retrospective studies have shown an association between metformin and reduced risk of AMD.

Objective

To investigate the association between metformin use and age-related macular degeneration (AMD).

Design, Setting, and Participants

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), to investigate the association of treatment with metformin or an intensive lifestyle modification vs placebo with preventing the onset of type 2 diabetes in a population at high risk for developing diabetes. Participants with retinal imaging at a follow-up visit 16 years posttrial (2017-2019) were included. Analysis took place between October 2019 and May 2022.

Interventions

Participants were randomly distributed between 3 interventional arms: lifestyle, metformin, and placebo.

Main Outcomes and Measures

Prevalence of AMD in the treatment arms.

Results

Of 1592 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. All 3 arms were balanced for baseline characteristics including age (mean [SD] age at randomization, 49 [9] years), sex (1128 [71%] male), race and ethnicity (784 [49%] White), smoking habits, body mass index, and education level. AMD was identified in 479 participants (30.1%); 229 (14.4%) had early AMD, 218 (13.7%) had intermediate AMD, and 32 (2.0%) had advanced AMD. There was no significant difference in the presence of AMD between the 3 groups: 152 (29.6%) in the lifestyle arm, 165 (30.2%) in the metformin arm, and 162 (30.7%) in the placebo arm. There was also no difference in the distribution of early, intermediate, and advanced AMD between the intervention groups. 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). 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).

Conclusions and Relevance

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. 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.

Fear of hypoglycemia in the parents of children and adolescents with diabetes: maladaptive or healthy response?

Sixty-one parents of children with insulin-dependent diabetes mellitus completed modified versions of the Hypoglycemic Fear Survey (HFS) and the Diabetes Quality of Life (DQOL) scale. They also indicated their child's history of hypoglycemic-related seizures or loss of consciousness (SLC) events. Parental HFS scores were significantly greater if their child had ever experienced a SLC event or experienced a SLC event within the past year. Parental HFS scores were positively correlated with general parental worry about their child having diabetes. Adolescent children who experienced a SLC event during the past year reported greater HFS scores, greater general worry about diabetes, and a greater negative impact of having diabetes compared with adolescents with no such history. Despite the greater fear of hypoglycemia in parents and adolescents, there was no significant difference in HbA1 values between children with or without any history of SLC events or children with or without a SLC event within the past year.

Comparison of obese NIDDM and nondiabetic women: short- and long-term weight loss

Previous research suggests that overweight patients with diabetes lose less weight than nondiabetics. We compared the response of obese women with NIDDM to nondiabetic controls, matched for age and weight, to a behavior weight loss program. Forty-three overweight women (20 NIDDM, 23 nondiabetic) participated in the study. NIDDM and nondiabetic subjects were treated together and received the same 16-week behavioral weight loss program. Dependent measures included weight, 3-day food records, physical activity, fasting plasma glucose, and questionnaires assessing eating behavior and depressive symptomatology. Weight loss of NIDDM and nondiabetic subjects at posttreatment was comparable (-7.4 +/- 5.3 kg vs. -6.4 +/- 3.8 kg, respectively). Changes in caloric intake, eating behavior, exercise and depressive symptomatology were also similar between the two groups. However, during the 1-year follow-up period, NIDDM subjects regained 5.4 +/- 6.1 kg compared to 1.0 +/- 6.7 kg for nondiabetics (p = .058). These data indicate that NIDDM subjects can lose as much weight as their nondiabetic peers during active treatment. Once treatment terminated, however, NIDDM subjects demonstrated poor weight loss maintenance. Thus the added motivation that comes from having diabetes and seeing improvements in glycemic control with weight loss were not sufficient to improve long term weight loss in diabetic subjects. A continuous care model of weight control may be particularly necessary for overweight patients with type II diabetes.

The effect of weight loss on change in waist-to-hip ratio in patients with type II diabetes

This study sought to determine whether weight loss would alter body fat distribution in obese men and women with type II diabetes. Subjects were 60 women and 33 men who participated in a year-long weight loss program. Weight losses of women and men, respectively, averaged 13.4 kg and 16.8 kg at six months and 11.2 kg and 13.1 kg at one year. WHR decreased significantly in both genders: for women, WHR decreased from 0.95 at baseline to 0.93 at six months and 0.94 at one year; for men WHR decreased from 0.99 at baseline to 0.96 at six months and 0.96 at one year. Subjects with greater upper body obesity at baseline did not lose more weight than subjects with less upper body obesity, but they did have greater reductions in WHR at six months in both genders and at one year in men. The magnitude of WHR reduction was strongly related to the amount of weight lost in men, but was not related to weight loss in women. Improvements in fasting glucose, fasting insulin, and HbA1 were significantly related to weight loss, but not to reductions in WHR. Thus, participation in a weight loss program had beneficial effects on body fat distribution in patients with type II diabetes, but these changes in WHR were not independently associated with improvements in glycemic control.

Analysis of changes in eating behavior and weight loss in type II diabetic patients. Which behaviors to change

To identify the behavior-change strategies that are most clearly related to weight loss, 106 patients with type II (non-insulin-dependent) diabetes completed the Eating Behavior Inventory (EBI) before and after participating in a behavioral weight-loss program and at 1-yr follow-up. The EBI is a standardized questionnaire that assesses behavioral strategies typically taught in a behavioral weight-loss program. Pretreatment scores on the EBI were not related to weight-loss outcome, but changes on the EBI in the direction of more frequent use of appropriate strategies were related to weight loss at both posttreatment and 1-yr follow-up. Specific strategies related to weight loss at both times were 1) eating foods that help in losing weight, 2) recording foods eaten, 3) refusing food offered by others, and 4) being able to stop eating when appropriate. However, few patients maintained frequent use of these strategies at follow-up. It is concluded that weight-loss programs should focus on the strategies most strongly related to weight loss and try to improve long-term use of these techniques.