Concerns persist about cardiovascular risk when diabetes develops during statin therapy. In Cardiovascular Diabetology, two retrospective cohort studies evaluated cardiovascular outcomes in individuals who developed diabetes during statin use compared with other statin-treated populations.

The analysis used data from the Korean National Health Insurance Service database from 2009 to 2020. From a source population of 1,500,959 adults, two cohorts were constructed. In Study 1, 4,371 individuals who used statins continuously for at least 730 days before a new diagnosis of type 2 diabetes mellitus (T2DM) were identified. These individuals were matched 1:1 to statin users who initiated therapy after a prior T2DM diagnosis. Matching was based on age, sex, and low-density lipoprotein cholesterol levels. In Study 2, 4,191 statin users who developed T2DM during follow-up were matched 1:1 with statin users who remained free of diabetes during the same period. The primary outcome was major adverse cardiovascular events (MACE), defined as myocardial infarction or stroke. All-cause mortality was a secondary outcome.

In Study 1, individuals who developed T2DM during statin therapy had a lower risk of MACE than those who initiated statins after diabetes diagnosis. The adjusted hazard ratio (aHR) was 0.607 (95% confidence interval [CI], 0.458-0.805; P = 0.0005). This difference was driven mainly by a lower stroke risk (aHR, 0.504; 95% CI, 0.357-0.711; P < 0.001). In Study 2, incident T2DM during statin use was not associated with increased MACE risk (aHR, 1.122; 95% CI, 0.784-1.605; P = 0.53) or all-cause mortality (aHR, 0.555; 95% CI, 0.290-1.063; P = 0.0758) compared with remaining diabetes-free.

These findings indicate that diabetes developing during statin therapy was not associated with excess cardiovascular risk or mortality.