Association of Diabetes Mellitus Status and Glycemic Control With Secondary Prevention Medication Adherence After Acute Myocardial Infarction

BACKGROUND: Cardioprotective medication adherence can mitigate the risk of recurrent cardiovascular events and mortality after acute myocardial infarction (AMI). We examined the associations of diabetes mellitus status and glycemic control with cardioprotective medication adherence after AMI. METHODS AND RESULTS: We performed a retrospective observational cohort study of 14 517 US veterans who were hospitalized for their first AMI between 2011 and 2014 and prescribed a beta‐blocker, 3‐hydroxy‐3‐methyl‐glutaryl‐CoA‐reductase inhibitor, and angiotensin‐converting enzyme inhibitor or angiotensin receptor blocker. The primary exposure was a diagnosis of type 2 diabetes mellitus; in diabetes mellitus patients, hemoglobin A1c (HbA1c) was a secondary exposure. The primary outcome was 1‐year adherence to all 3 medication classes, defined as proportion of days covered ≥0.8, assessed using adjusted risk differences and multivariable Poisson regression. Of 14 517 patients (mean age, 66.3 years; 98% male), 52% had diabetes mellitus; 9%, 31%, 24%, 15%, and 21% had HbA1c <6%, 6% to 6.9%, 7% to 7.9%, 8% to 8.9%, and ≥9%, respectively. Diabetes mellitus patients were more likely to be adherent to all 3 drug classes than those without diabetes mellitus (adjusted difference in adherence, 2.1% [0.5, 3.7]). Relative to those with HbA1c 6% to 6.9%, medication adherence declined with increasing HbA1c (risk ratio of achieving proportion of days covered ≥0.8, 0.99 [0.94, 1.04], 0.93 [0.87, 0.99], 0.82 [0.77, 0.88] for HbA1c 7–7.9%, 8–8.9%, and ≥9%, respectively). CONCLUSIONS: Although diabetes mellitus status had a minor positive impact on cardioprotective medication adherence after AMI, glycemic control at the time of AMI may help identify diabetes mellitus patients at risk of medication nonadherence who may benefit from adherence interventions after AMI.