The Impact of GLP-1 Receptor Agonists on Patients with Diabetes on Insulin Therapy

Objective: The clinical benefit of adding a glucagon-like peptide-1 receptor agonist (GLP-1RA) to basal-bolus or very high dose insulin regimens is unclear. This study investigated the impact of adding a GLP-1RA to a spectrum of insulin regimens (basal, basal-bolus, and U-500) to determine the impact on hemoglobin A1c (HbA1c), weight loss, and total daily insulin dose (TDD) over the course of 12 months.Methods: A retrospective chart review was conducted on 113 participants with type 2 diabetes mellitus using insulin therapy. Each participant's HbA1c, body weight, and TDD were recorded prior to initiation of GLP-1RA therapy and at the 3, 6, and 12-month time points while on combination therapy.Results: Across all participants, the HbA1c values decreased significantly from a baseline of 8.9 (74 mmol/mol) ± 0.14% to 8.2 (66 mmol/mol) ± 0.14% (P<.01) in the first 3 months, 8.0 (64 mmol/mol) ± 0.12% (P<.01) at 6 months, to 8.3 (67 mmol/mol) ± 0.14% (P<.01) at 12 months. There was no significant decrease in weight or TDD with the addition of a GLP-1RA overall or in different insulin groups. However, there was a clinically significant decrease in weight over the study duration.Conclusion: The results of this study suggest that adding a GLP-1RA to various insulin regimens may help to achieve glycemic goals while avoiding the less desirable side effects of weight gain and increasing insulin regimens. However, the expected weight loss and decrease in TDD may not be as sizable in the clinical setting.Abbreviations: DCOE = Diabetes Center of Excellence; DM = diabetes mellitus; GLP-1RA = glucagon-like peptide-1 receptor agonist; HbA1c = hemoglobin A1c; RCT = randomized controlled trial; TDD = total daily dose