Nicorandil and diabetes: a nested case-control study to examine a signal generated by prescription-event monitoring

Objective: To investigate a signal generated by an observational cohort study that treatment with the potassium channel opener drug, nicorandil, is associated with an increased incidence of diabetes mellitus (DM). Methods: Nested case-control study within cohorts used for prescription-event monitoring. Results: The cohort study of nicorandil showed that there was a significant difference between the event rate for DM in the first month after starting nicorandil, compared to months 2-6 (difference in rates 1.93, 99% CI 0.7-3.1, per 1000 patient months of treatment). However, the adjusted odds ratio from the case-control study was 1.42 (95% CI 0.66-3.07) for incidence of newly diagnosed DM in nicorandil versus four comparator drugs. Conclusions: The nested case-control study was used as a hypothesis-testing instrument for following up a signal of a possible drug reaction to nicorandil. It showed no evidence that nicorandil is associated with increased incidence of newly diagnosed DM.