The group found that lower doses of the drug also appeared to reduce the risk of glaucoma, but not enough to rule out the possibility that this was due to chance.
A study at the University of Michigan in Ann Arbor has found that Metformin, a pill that lowers blood sugar in people with diabetes, might also reduce their risk of developing glaucoma.
Glaucoma, which is an eye disease can lead to vision loss and blindness.
Although the results can’t prove the drug prevents glaucoma, researchers found that diabetics taking higher doses of metformin were less likely to develop glaucoma than those who used smaller doses or didn’t take the pill at all.
Senior study author and director of the glaucoma research center at the University of Michigan, Julia Richards however said more research is needed to better understand whether patients might benefit from taking more medicine just to ward off glaucoma.
Moreso because metformin has worse side effects at higher doses.
The study focused on the most common variation of glaucoma, known as open-angle glaucoma, which starts with gradual loss of peripheral vision.
The researchers reviewed a database with a decade of health claims and prescription data for 40 million patients, focusing their analysis on a subset of about 150,000 people with diabetes who also had multiple eye exams to screen for glaucoma.
According to Reuters, at the start of the study period in 2001, all of the (mostly white) patients were at least 40 years old and roughly half were 55 or older.
Over the course of the study, about 6,000 people, or 4 percent of participants, developed glaucoma. Patients over age 65 were three times more likely to be diagnosed with glaucoma than the youngest participants, aged 40 to 45.
After adjusting for age and other variables, the researchers found that people who took the equivalent of more than 1.5 grams of metformin a day for two years were 25 percent less likely to develop glaucoma.
Many diabetics are initially prescribed 1 gram a day or less of metformin and monitored for side effects such as cramping, diarrhea or rarer, more serious complications like seizures, chest pain and depression.
If patients don’t have side effects, their dose might gradually be increased to about 2 to 2.5 grams a day.
Thus the group found that lower doses of the drug also appeared to reduce the risk of glaucoma, but not enough to rule out the possibility that this was due to chance.
Dr. Pradeep Ramulu, a researcher at the Wilmer Eye Institute at Johns Hopkins Medicine in Baltimore described the findings as "intriguing, though it is still too early to recommend that diabetics be given higher doses of metformin based on the study".