OBJECTIVES : Switching between different types of insulin may reflect adverse effects and non-adherence in patients with type 2 diabetes. However, little is known about the rates of switching in a real-world setting. Our objective was to describe and compare switching rates among new users of neutral protamine Hagedorn (NPH) insulin and long-acting insulin analogs (glargine, detemir, degludec) among patients with type 2 diabetes.

METHODS : We conducted a retrospective cohort study using data from the Clinical Practice Research Datalink (CPRD) Aurum, a primary care database from the United Kingdom. We created a cohort of patients receiving their first-ever prescription for basal insulin, which included NPH or long-acting insulin analogs (detemir, glargine, degludec) between January 1^st, 2003 and December 31^st, 2018. We defined incident treatment switch as a new prescription for a basal insulin not previously prescribed. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for switching between each of the three long-acting insulin analogs and NPH.

RESULTS : Our cohort included 85,369 patients who initiated basal insulin treatment. A total of 14,693 treatment switches occurred over 435,908 person-years of follow-up (overall rate: 33.7, 95% CI: 33.0, 34.7 per 1000 person-years). After adjusting for potential confounders, new users of detemir were more likely to switch treatments than new users of NPH (HR: 1.31, 95% CI: 1.25, 1.37), while new users of glargine were less likely to switch treatment than new users of NPH (HR: 0.85, 95% CI: 0.82, 0.88). While a trend was observed for degludec versus NPH (HR: 1.19, 95% CI: 0.92, 1.56), this analysis was inconclusive due to sparse data.

CONCLUSIONS : In this population-based study, detemir was associated with the greatest rate of switching while glargine was associated with the lowest rate among patients with type 2 diabetes in a real-world setting.