| Abstract: | Objective: The mechanism of the beneficial effect of calcium channel blockers (CCBs), especially verapamil, on the development of type 2 diabetes mellitus (T2DM) has been described. Previous clinical studies aiming to confirm these results were flawed by inappropriate comparator drugs or study designs. This study compared the incidence of T2DM in adults prescribed oral verapamil and propensity score-matched adults prescribed other oral CCBs. Methods: This retrospective population-based cohort study used Taiwan's National Health Insurance Research Database during 2000-2011. T2DM was defined according to the International Classification of Diseases, Ninth Revision, Clinical Modification. Results: During follow-up periods of 41,958 and 42,118 person-years, 269/4930 patients in the verapamil cohort and 340/4930 patients in the matched cohort, respectively, developed T2DM. The incidence rates were 6.41 and 8.07 per 1000 population per year among verapamil and other CCB users, respectively. The adjusted hazard ratio (HR) for T2DM associated with use of verapamil (vs. other CCBs) was 0.80 (95% confidence interval [CI], 0.68-0.94; P = 0.006). After excluding those followed for <180 or <365 days to avoid bias derived from delayed diagnosis, adjusted HRs remained significant (0.79, 95% CI, 0.67-0.93, P = 0.005 and 0.77, 95% CI, 0.65-0.91, P = 0.002, respectively). Only the interaction term for age was significant (P = 0.009). Verapamil had a more prominent effect on those aged > 65 years (P< 0.001). Conclusions: In patients with no known history of DM, oral verapamil use was associated with a decreased incidence of T2DM compared with other CCBs. |
