Medication Adherence and Its Determinants in Patients with Type 2 Diabetes Mellitus Attending an Internal Medicine Outpatient Department.

Abstract

Background: Medication adherence remains a central element in achieving optimal glycemic control in type 2 diabetes mellitus. Many patients struggle to follow prescribed therapy, leading to early metabolic deterioration and a higher burden of complications. Understanding the factors that shape adherence in routine clinical settings can help guide targeted interventions.

Materials and methods: A hospital-based observational study was conducted in the Internal Medicine Outpatient Department of the Dominica China Friendship Hospital, Dominica, between August 2024 and January 2025. Adults diagnosed with type 2 diabetes mellitus and on treatment for at least six months were eligible. A total of 420 patients were enrolled. Medication adherence was measured using the eight-item Morisky medication adherence scale (MMAS-8). Sociodemographic, clinical and behavioral characteristics were documented through structured interviews and medical records. Data were analyzed using chi-square tests to assess associations and multivariate logistic regression was applied to identify independent predictors of adherence.

Results: Participants had a mean age of 54.6 ± 10.8 years, with males comprising 58.3% of the cohort. According to MMAS-8 scoring, 29.3% demonstrated high adherence, 41.9% moderate adherence and 28.8% low adherence (mean score 6.21 ± 1.54). Forgetfulness, discontinuation of therapy after symptomatic improvement and financial constraints were the most commonly reported barriers. On multivariable analysis, higher education, simplified drug regimen, regular follow-up and good glycemic control emerged as independent predictors of good adherence. Participants with high adherence exhibited significantly lower mean HbA1c levels compared with poorly adherent individuals (6.8 ± 0.9% vs 8.3 ± 1.1%, p < 0.001).

Conclusion: Medication adherence was suboptimal in a substantial proportion of adults with type 2 diabetes mellitus. Interventions that strengthen diabetes education, reduce regimen complexity and promote structured follow-up may improve adherence and support better glycemic control.