The meta-analysis included more than 11,000 patients with between 8 and 9 years of mean follow-up periods.
Diabetes medication is linked to a reduced risk of open-angle glaucoma (OAG) and age-related macular degeneration (AMD), but not cataracts, according to an original investigation published in JAMA Ophthalmology.
Led by Wishal D. Ramdas, MD, PhD, Department of Ophthalmology, Erasmus University Medical Center, investigators evaluated 3 independent studies conducted between 1990 and 2014 in order to determine the association between diabetes and eye diseases such as OAG, AMD, and cataracts. The study participants were monitored for OAG, AMD and cataracts and had at least 1 follow up visit. Plus, the investigators collected data on the participants’ glucose levels, diabetes medication use, and ophthalmological exams.
Ultimately, the investigators included 11,260 participants in their analysis. The mean age of the participants was 65 years and a little more than half of the patients were women (58 percent, or 6,610). Type 2 diabetes had been diagnosed in 2,406 patients. Metformin had been prescribed to about half of those patients, while 20 percent received other diabetes medication, and 21 percent received lifestyle advice only, the investigators observed.
Those with type 2 diabetes and eye disease were significantly older than those without eye disease, the study authors noted, and cataract was more frequently present in woman compared to men.
Eye disease diagnoses were as follows, according to the investigators:
However, in untreated type 2 diabetes, the study authors noted a higher risk of OAG, AMD, and cataract for the participants. When type 2 diabetes was treated with metformin, the study authors observed a lower risk of OAG. Furthermore, other diabetes medication such as insulin or sulfonylurea derivates had a lower risk of AMD, while no diabetes medication was associated with a risk for cataract.
The mean follow up period was 9.9 years for OAG, 8.2 years for AMD, and 7.9 years for cataract. In that time, 4,191 participants developed OAG (182 patients), AMD (869 patients), or cataract (3,140 patients). From that group, 285 patients received metformin while 145 others received other diabetes medication.
The study authors determined that the lifetime risk for OAG for patients taking metformin was lower than for patients with untreated diabetes and those taking other diabetes medication.
The lifetime risk for AMD in patients taking metformin was similar to those going untreated for their diabetes. The patients taking other diabetes medication had the lowest lifetime risk for AMD, the study authors wrote.
The lifetime risk for cataract did not differ between patients being treated with metformin, other diabetes medication, untreated diabetes patients, or individuals without diabetes.
“Results of this cohort study suggest that diabetes medication was associated with a reduced risk of OAG and AMD; however, no association was found between treatment with diabetes medication and cataract,” Ramdas concluded. “Metformin was associated with a lower risk of OAG, and treatment with other diabetes medication was associated with a lower risk of AMD.”
The study, "Association of Diabetes Medication With Open-Angle Glaucoma, Age-Related Macular Degeneration, and Cataract in the Rotterdam Study," was published in JAMA Ophthalmology.