From Initiation, Implementation, to Discontinuation: An Umbrella Review of Determinants of Medication Adherence in Diabetes

Abstract

Medication adherence is a key determinant of glycemic control, and it comprises three interrelated phases, namely, initiation, implementation, and discontinuation, as conceptualized by the ABC taxonomy. Therefore, this umbrella review aims to identify and classify factors influencing medication adherence among patients with diabetes across the three phases. A systematic search was conducted in MEDLINE, EBSCO, and Scopus (inception to May 2025) to identify systematic reviews on factors associated with medication adherence in adults with type 1 or 2 diabetes mellitus. Data were then extracted and mapped to the ABC taxonomy and five conceptual domains. Methodological quality was assessed using AMSTAR 2, and a total of 28 systematic reviews comprising 795 studies were included. The majority of the evidence found focused on implementation, with limited studies examining initiation and discontinuation. The results showed that initiation was primarily influenced by patient-related factors (e.g., fear of injections, health beliefs, and self-efficacy) and socioeconomic factors (e.g., income, education, and social support). Meanwhile, implementation was determined by a broader range of factors, including health literacy, regimen complexity, adverse effects, and financial burden. In the discontinuation phase, financial constraints, insurance, treatment efficacy, and adverse effects were the most frequent factors. The current review emphasizes that medication adherence in diabetes is a multifactorial, phase-dependent process characterized by distinct but overlapping determinants across the adherence continuum. The majority of the reviews were judged to be of moderate to high quality. Future original studies are advised to consistently apply the ABC taxonomy to clearly distinguish adherence phases and to generate phase-specific evidence that can better inform targeted interventions.