MedicalResearch.com Interview with: Julia E. Richards, Ph.D. Harold F. Falls Professor of Ophthalmology and Visual Sciences Professor of Epidemiology Director, Glaucoma Research Center The University of Michigan Medical Research: What is the background for this study? Response: We have a special interest in how the developmental processes of aging increase the risk of late onset diseases. We wondered whether drugs that target known aging pathways might be able to reduce risk of late onset disease. In the aging field, an emerging area of interest has been the category of drugs called caloric restriction mimetic (CRM) drugs, which have been found to extend life span and to reduce risk or delay onset of some late-onset diseases. These caloric restriction mimetic drugs target a set of pathways that have come to be seen as playing roles in longevity. One of these caloric restriction mimetic drugs, metformin, happens to also be one of the most common drugs used in the treatment of type 2 diabetes. Glaucoma is a leading cause of blindness worldwide and classical open-angle glaucoma shows onset in late middle age or late age, so we hypothesized that a caloric restriction mimetic drug might be able to reduce the risk of open-angle glaucoma. We used data from a large health services database to compare the rate at which open-angle glaucoma developed in individuals with diabetes mellitus who used metformin versus those who did not use metformin. We predicted that metformin would be associated with reduced risk of open-angle glaucoma. Medical Research: What are the main findings? Response: We found that use of metformin was associated with reduced risk of open-angle glaucoma. A 2 gram per day dose of the CRM drug metformin for two years was associated with a 20.8% reduction in risk of developing open-angle glaucoma. When we looked at the highest quartile of drug prescribed (>1,100 grams over a two year period) we found a 25% reduction in risk relative to those taking no metformin. This risk reduction is seen even when we account for glycemic control in the form of glycated hemoglobin, and use of other diabetes drugs was not associated with reduced risk of open-angle glaucoma. A possible explanation for our findings might be that the mechanism of risk reduction is taking place by CRM drug mechanisms that target aging pathways rather than through glycemic control of diabetes. In the long run, the approaches to late onset diseases in general will become much more powerful if we can use parallel approaches that simultaneously target both the aging processes going on and the disease-specific pathways going on. In the literature we see caloric restriction mimetic drugs metformin, rapamycin and resveratrol all being explored for their ability to target points in aging pathways in ways that can impact the risk of a variety of late-onset diseases, so it will be important for those interested in the risk factors affecting late onset diseases to pay attention to how caloric restriction mimetic drugs might be altering risk for those late onset diseases.