Medication Adherence and Risks of Mortality and End-Organ Damage in Asian Patients with Type 2 Diabetes: A Cohort Study from Southern Taiwan

<b>Background</b>: Medication adherence is a critical component of effective management in type 2 diabetes mellitus (T2DM). Although previous studies have explored the relationship between adherence and clinical outcomes, the strength and consistency of these associations have not been fully elucidated and remain unclear. In particular, evidence derived from patient-reported measures of adherence is limited, and the prognostic significance of adherence as assessed from the patient perspective is not clearly defined. <b>Methods</b>: We conducted a prospective observational cohort study consisting of adult patients with T2DM who received regular outpatient follow-up. Medication adherence was assessed at the time of enrollment using the eight-item Morisky Medication Adherence Scale (MMAS-8) and was categorized as good, moderate, or poor. Participants were subsequently followed for five years to ascertain clinical outcomes. Primary outcomes were assessed longitudinally and included the occurrence of nonfatal myocardial infarction, heart failure, nonfatal stroke, and progression to end-stage kidney disease (ESKD), as well as all-cause mortality. Secondary outcomes included changes in glycated hemoglobin (HbA1c), estimated glomerular filtration rate (eGFR), and low-density lipoprotein (LDL) levels. <b>Results</b>: No statistically significant differences were observed in the incidence of nonfatal myocardial infarction, heart failure, nonfatal stroke, or progression to ESKD across adherence groups. In contrast, all-cause mortality was significantly higher among patients with poor adherence. With respect to metabolic outcomes, HbA1c and eGFR at five years were comparable across adherence groups, whereas LDL levels were significantly higher in patients with poor adherence. <b>Conclusions</b>: Poor medication adherence as assessed at baseline may be related to a higher risk of all-cause mortality and poorer lipid control, while no statistically significant differences were observed for nonfatal cardiovascular or renal outcomes.