BACKGROUND AND PURPOSE:

• As of yet, there are no preventative measures effective against age-related macular degeneration (AMD)
  • Metformin has protective outcomes in multiple age-associated diseases such as cancer, CVD and dementia
• Blitzer et al. (JAMA Ophthalmology, 2021) examined whether metformin use is associated with reduced odds of developing AMD

METHODS:

• Case-control population-based study 
  • Nationwide health insurance claims database
• Participants
  • ≥55 years 
  • Newly diagnosed with AMD between 2006 to 2017
• Exposures
  • Dosage of metformin
  • Exposure to other prescribed medications
• Study design
  • Patients with newly diagnose AMD were defined as cases and matched with control participants
  • Stratified by age group
  • Subgroup analysis based on diabetes diagnosis  
  • Data on known AMD risk factors were also obtained
• Primary outcome
  • Risk of developing AMD

RESULTS:

• AMD group: 312,404 individuals | Control group: 312,376 individuals
  • Age range 55 to 107 years
• The AMD group had a slightly higher percentage of participants with diabetes
  • AMD: 26.0%
  • Control group: 25.5%
• Use of metformin was associated with reduced odds of developing AMD
  • Odds ratio (OR) 0.94 (95% CI, 0.92 to 0.96)
• The association was dose dependent | Low to moderate doses of metformin were associated with the greatest benefit (dosages over 2 years)
  • 1 to 270 g : OR 0.91 (95% CI, 0.88 to 0.94)
  • 271-600 g: OR 0.90 (95% CI, 0.87 to 0.93)
  • 601-1080 g: OR 0.95 (95% CI, 0.92 to 0.98)
  • >1080 g: no reduced odds of AMD

Diabetes subanalysis

• Both reduction in odds and the dose-dependent response were seen in a diabetic cohort
• Diabetes and no diabetic retinopathy
  • Decreased risk for AMD: OR 0.93 (95% CI 0.91 to 0.95)
• Diabetes with existing diabetic retinopathy
  • Increased risk for AMD: OR 1.07 (95% CI 1.01 to 1.15)

CONCLUSION:

• The use of metformin was associated with reduced odds of AMD
  • The association was dose-dependent, with low to moderate doses conferring the greatest benefit
• This association was preserved in patients with diabetes, although not in cases where diabetic retinopathy was present
• The design of this study can assess association but not causation
  • This study suggests possible role for metformin as a therapeutic agent for AMD but further research is needed
• The authors state

This case-control study using a large, national sample suggests that metformin use over 2 years in adults aged 55 years and older is associated with 5% to 10% reduced odds ratio of developing AMD

Learn More – Primary Sources:

Association of Metformin Use With Age-Related Macular Degeneration: A Case-Control Study

Related ObG Topics: