Absence of Interaction Between 5α‐Reductase Inhibitors and Glucocorticoids on Incidence of Myocardial Infarction in People With Type 2 Diabetes

Aims People with Type 2 diabetes experience higher cardiometabolic risk, and both synthetic glucocorticoids and use of 5α‐reductase inhibitors have been individually linked to increased risk of myocardial infarction. We tested whether the increase in risk is exacerbated by co‐prescription of both drugs. Materials and Methods We performed a population‐based cohort study in the Scottish Diabetes Research Network‐National Diabetes Dataset (SDRN‐NDS) and IQVIA Medical Research Data‐UK (IMRD‐UK). Patients with Type 2 diabetes aged ≥ 40 years receiving 5α‐reductase inhibitors or tamsulosin, who were incident users of systemic glucocorticoids during 2006–2021 were included. We modelled the joint effect of 5α‐reductase inhibitors and cumulative exposure to glucocorticoids on the risk of myocardial infarction using a time‐varying Cox proportional hazards model. Results A total of 13 161 patients with Type 2 diabetes were included in SDRN‐NDS and 15 084 in IMRD‐UK. Mean age was 71.4 ± 9.6 and 72.3 ± 9.4 years, with mean follow‐up of 4.7 (3.6) and 5.6 (4.0) years, respectively. Median (IQR) total glucocorticoids exposure was 210 (96–630) and 420 (200–1240) prednisolone‐equivalent milligram. Risk for myocardial infarction was increased among users of 5α‐reductase inhibitors (HR [95% CI]: SDRN‐NDS, 1.21 [1.02–1.43]; IMRD‐UK, 1.27 [1.02–1.59]) and per SD increase in cumulative glucocorticoid exposure (HR [95% CI]: SDRN‐NDS, 1.09 [1.03–1.14]; IMRD‐UK, 1.08 [1.01–1.15]). We did not observe a multiplicative interaction (SDRN‐NDS, p = 0.44; IMRD‐UK, p = 0.68) between the use of the two drugs. Conclusion People with Type 2 diabetes exposed to 5α‐reductase inhibitors or glucocorticoids are at an increased risk of myocardial infarction, although a multiplicative interaction between the use of the two drugs was not found.