The prevalence of adherence to insulin therapy in patients with diabetes: A systematic review and meta-analysis

Background: Adherence to insulin therapy is crucial to achieving good glycemic control for patients with type 1 diabetes (T1D) or type 2 diabetes (T2D). A comprehensive estimation of adherence to insulin therapy in patients with diabetes is currently lacking. Objective: To explore the prevalence of adherence to insulin therapy in patients with both T1D and T2D. Methods: A systematic search was performed using the following databases: PubMed, EMBASE, Cochrane CENTRAL, and ProQuest Dissertation and Theses from the inception of each database to August 2023. Cross-sectional studies were included if they met the following criteria: (1) conducted in patients with T1D or T2D; (2) reported adherence to insulin therapy. The Joanna Briggs Institute (JBI) critical appraisal checklist for studies reporting prevalence data was used to assess the quality of included studies. Pooled estimates of the prevalence of adherence to insulin were calculated as a percentage together with a 95 % confidence interval (95%CI) using a random-effect model. All analyses were conducted using STATA 15 (College Station, Texas, United States); PROSPERO (CRD42022322323). Results: Search results yielded 14,914 articles, of these 57 studies with a total of 125,241 patients met the inclusion criteria. The overall estimated prevalence of adherence to insulin therapy in both types of diabetes was 55.37 % (95%CI: 48.55 %-62.19 %). The adherence for T1D was 52.63 % (95 % CI: 37.37 %-67.87 %), whereas the adherence for T2D was 52.55 % (95 % CI: 43.08 %-62.01 %). The prevalence of adherence in lower middleincome countries was 56.79 % (95 % CI: 27.85 %-85.74 %). Conclusions: The overall prevalence of adherence to insulin therapy was remarkably low. This requires attention from healthcare practitioners and policymakers to implement appropriate strategic approaches to improve adherence to insulin therapy.