Introduction: Metformin is the most commonly used glucose lowering agent for type 2 diabetes. Recent evidence suggests metformin facilitates the proliferation and migration of stem cells, which in turn have shown to improve bladder overactivity in animal models. The objective of this study was to determine if metformin use was associated with a lower rate of overactive bladder (OAB) medication use.
Methods: We conducted a retrospective nested case-control cohort study using population-based health-care administrative databases in Ontario, Canada, between 2002-2019. Our cohort was defined as diabetics aged 66 years or older. Cases were defined as patients in our cohort who had received a prescription for an OAB medication, and then matched with up to 4 controls based on age, sex, cohort entry date, and diabetes diagnosis date. Exposure was defined as a new prescription for metformin prior to receiving a prescription for an OAB medication. Adjusted odds ratios (aOR) were estimated using conditional logistic regression. Sensitivity analysis was done to assess for the relationship between cumulative days’ supply of metformin and use of OAB medications.
Results: Within our cohort of 2,233,084 diabetics, there were 16,549 case subjects who received a prescription for an OAB medication, and 64,171 matched control subjects. We found a positive association between OAB medication use and metformin use (aOR = 1.07, 95% CI = 1.03-1.12). Summed days’ supply of metformin was also associated with OAB medication use, except when summed metformin days was >2220 (aOR = 1.02, 95%CI = 0.95-1.10).
Conclusions: This study found older diabetics exposed to metformin had a slightly higher rate of OAB medication use, until 2220+ days’ metformin supply, whereafter no association was found. This suggests there is no protective role for metformin in the prevention of OAB in this patient population.
Source of Funding: University of Toronto Functional Urology Research Program