Verapamil Use Is Associated With Reduction of Newly Diagnosed Diabetes Mellitus

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. 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 from 2000 to 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 of 4930 patients in the verapamil cohort and 340 of 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 to 0.94; P = 0.006]. After exclusion of patients followed for <180 days or <365 days (to avoid bias derived from delayed diagnosis), adjusted HRs remained significant [0.79 (95% CI, 0.67 to 0.93; P = 0.005) and 0.77 (95% CI, 0.65 to 0.91; P = 0.002), respectively]. Only the interaction term for age was significant (P = 0.009). Verapamil had a more prominent effect on patients aged older than 65 years (P < 0.001). Conclusions: In patients with no known history of diabetes mellitus, oral verapamil use was associated with a decreased incidence of T2DM compared with other CCBs.