Insulin Dosage Adjustments After Initiation of GLP-1 Receptor Agonists in Patients With Type 2 Diabetes

Background: Combination of insulin and GLP-1RAs have shown reductions in the HbA1c, body weight, and the risk of hypoglycemia. To date, there are conflicting data regarding the effect of GLP-1RAs on insulin dosage(s). Objective: The objective of this study was to evaluate adjustments of insulin doses upon initiation of GLP-1RAs. Methods: This was a retrospective chart review of patients on insulin therapy initiated on GLP-1RAs at NYU Langone Health. Patients were included in the study if they were at least 18 years of age, history of type 2 diabetes, and were on concurrent basal or mixed insulin therapy. 45 patients met inclusion criteria and were included in the study analysis. The primary endpoint was the median change in overall basal insulin doses. Secondary endpoints included median changes in total basal, mixed, and bolus insulin doses, oral antidiabetic medications and GLP-1RA doses, HbA1c, body weight, fasting glucose, and creatinine clearance. Safety results included any adverse reactions to insulin and/or GLP-1RA. Results: In the per-protocol analysis, there was a significant reduction in overall total basal insulin doses from baseline to week 24 (50 units vs. 44 units, p < 0.05). There was a median reduction in patients receiving glargine (50 units vs. 44 units) and detemir (29 units vs. 21.5 units). Conclusions: Use of GLP-1RAs after 24 weeks resulted in a statistically significant reduction in overall total basal insulin dosages from baseline. The median HbA1C in our patient population was >8%. Consider a ≥10% reduction in the overall basal insulin dose upon initiation of GLP-1RA in patients with a HbA1C >8%.