A Class Comparison of Medication Persistence in People with Type 2 Diabetes: A Retrospective Observational Study

Introduction: Longer medication persistence in type 2 diabetes (T2D) is associated with improved glycaemic control. It is not clear which oral therapies have the best persistence. The objective of this study was to compare medication persistence across different oral therapies in people with T2D. Methods: We performed a retrospective cohort analysis using a primary-care-based population, the Royal College of General Practitioners Research and Surveillance Centre cohort. We identified new prescriptions for oral diabetes medication in people with type 2 diabetes between January 1, 2004 and July 31, 2015. We compared median persistence across each class. We also compared non-persistence (defined as a prescription gap of >= 90 days) between classes, adjusting for confounders, using Cox regression. Confounders included: age, gender, ethnicity, socioeconomic status, alcohol use, smoking status, glycaemic control, diabetes duration, diabetes complications, comorbidities, and number of previous and concurrent diabetes medications. Results: We identified 60,327 adults with T2D. The majority 42,810 (70.9%) of those had one or more oral medications prescribed; we measured persistence in those patients (who were prescribed 55,728 oral medications in total). Metformin had the longest median persistence (3.04 years; 95% CI 2.94-3.12). The adjusted hazard ratios for non-persistence compared with metformin were: sulfonylureas HR 1.20 (1.16-1.24), DPP-4 inhibitors HR 1.43 (1.38-1.49), thiazolidinediones HR 1.71 (95% CI 1.64-1.77), SGLT2 inhibitors HR 1.04 (0.93-1.17), meglitinides HR 2.25 (1.97-2.58), and alpha-glucosidase inhibitors HR 2.45 (1.98-3.02). The analysis of SGLT2 inhibitors was limited by the short duration of follow-up for this new class. Other factors associated with reduced medication persistence were female gender, younger age, and non-white ethnicity. Conclusions: Persistence is strongly influenced by medication class and should be considered when initiating treatments.