Evaluation of Insulin Dosage After the Addition of Tirzepatide Compared With Semaglutide or Dulaglutide in Patients With Type 2 Diabetes

OBJECTIVE The purpose of this study was to evaluate insulin dose requirements after the addition of the dual glucose-dependent insulinotropic polypeptide/glucagon-like peptide 1 (GLP-1) receptor agonist tirzepatide compared with the GLP-1 receptor agonists injectable semaglutide and dulaglutide in people with type 2 diabetes. RESEARCH DESIGN AND METHODS This was a retrospective cohort study using chart review of electronic health records to identify patients from a single academic medical center with type 2 diabetes who were initiated on tirzepatide, injectable semaglutide, or dulaglutide from 1 July 2021 to 31 May 2023 while on concomitant insulin therapy (basal with or without bolus or premixed insulin). RESULTS A total of 135 patients were included in the study. The median percentage change in insulin requirement was 0% at 4–6 weeks (P = 0.286), −16.67% at 3 months (P <0.001), −51.03% at 6 months (P <0.001), and –58.33% at 12 months (P = 0.013) for the tirzepatide group (n = 45) and 0% at 4–6 weeks, 3 months, and 6 months and −12.50% at 12 months in the combined dulaglutide and semaglutide group (n = 90). Mean change in weight at 6 months was −8.5813 kg in the tirzepatide group and −3.4111 kg in the dulaglutide and semaglutide group (P <0.001). The most commonly reported adverse events in the tirzepatide group were decreased appetite, nausea, and vomiting. CONCLUSION In patients with type 2 diabetes who were also on insulin, tirzepatide led to significantly lower insulin requirements after 3, 6, and 12 months of use compared with dulaglutide and semaglutide. Tirzepatide also led to significantly more weight loss compared with dulaglutide and semaglutide and yielded a larger decrease in A1C overall without increasing side effects.