Medication adherence in patients with type 2 diabetes after disability onset: a difference-in-differences analysis using nationwide data

Background: Effectively managing the coexistence of both diabetes and disability necessitates substantial effort. Whether disability onset affects adherence to type 2 diabetes medication remains unclear. This study investigated whether disability onset reduces such adherence and whether any reduction varies by disability type. Methods: This study used the National Disability Registry and National Health Insurance Research Database from Taiwan to identify patients with type 2 diabetes who subsequently developed a disability from 2013 to 2020; these patients were matched with patients with type 2 diabetes without disability onset during the study period. Type 2 diabetes medication adherence was measured using the medication possession ratio (MPR). A difference-in-differences analysis was performed to determine the effect of disability onset on the MPR. Results: The difference-in-differences analysis revealed that disability onset caused a reduction of 5.76% in the 1-year MPR (P < 0.001) and 13.21% in the 2-year MPR (P < 0.001). Among all disability types, organ disabilities, multiple disabilities, rare diseases, and a persistent vegetative state exhibited the largest reductions in 2-year MPR. Conclusions: Policies aimed at improving medication adherence in individuals with disabilities should consider not only the specific disability type but also the distinct challenges and barriers these patients encounter in maintaining medication adherence.