Name: Evaluation of Insulin Requirements After Initiation of GLP-1 Receptor Agonists Versus GLP-1/GIP Receptor Agonist
Start: 2025-04-24T11:20:00-0400
End: 2025-04-24T11:35:00-0400

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Thursday April 24, 2025 11:20am - 11:35am EDT

Athena D

Title:
Evaluation of Insulin Requirements After Initiation of GLP-1 Receptor Agonists Versus GLP-1/GIP Receptor Agonist

Authors:

Omar Mouna, PharmD
Kate O’Connor, PharmD, BCACP, BC-ADM

Objective:
Determine the impact of initiating GLP-1 Receptor Agonists compared to GLP-1/GIP Receptor Agonists on total daily insulin requirements in adults with Type 2 Diabetes Mellitus after 6 months.

Self Assessment Question:
Does initiation of GLP-1/GIP receptor agonist therapy show statitistical significance in reducing insulin requirements at 6 months compared to initiation of GLP-1 receptor agonist therapy?

Background (168 words)
Incretin-based therapies, including GLP-1 receptor agonists (GLP-1 RAs) and the dual GLP-1/GIP receptor agonist (GLP-1/GIP RA), tirzepatide, are increasingly utilized in the management of type 2 diabetes mellitus (T2DM). These agents improve glycemic control and offer additional benefits, such as weight reduction and cardiovascular risk mitigation. For patients requiring insulin therapy, the initiation of GLP-1 RAs has demonstrated potential in reducing daily insulin requirements by enhancing endogenous insulin secretion and suppressing glucagon release. The recent introduction of tirzepatide, a dual incretin receptor agonist, has shown even greater efficacy in glycemic control and weight loss compared to traditional GLP-1 RAs in clinical trials. However, limited real-world data exist on the comparative impact of these therapies on insulin dose adjustments in patients already on insulin. Understanding the different impact of GLP-1 RAs versus GLP-1/GIP RAs on insulin requirements may guide therapy selection, optimize insulin regimens, and minimize dose-related side effects. This study aims to evaluate the impact of initiating these incretin-based therapies on daily insulin requirements in patients with T2DM.

Methods (182 words)
This was a single-center, IRB-approved, retrospective medical record review, conducted at Wellstar MCG Health’s outpatient clinics, and included adult patients 18 years and older who were initiated on incretin-based therapy while concurrently being on insulin therapy between the dates of July 1, 2022 and December 31, 2023. Patients were excluded if they had type 1 diabetes, had insulin added to their regimen after initiating incretin-based therapy, were administering sliding scale prandial insulin, or began an oral GLP-1 RA. The primary outcome assessed was percent change in total daily insulin requirement from baseline in individuals who initiated GLP-1 RAs versus GLP-1/GIP RAs after 6 months of agent initiation. Secondary outcomes evaluated changes in hemoglobin A1c (HgbA1c) between the two groups from baseline to 6 months, requirement of additional antidiabetic medications after initiation of incretin-therapy at 6 months, and percentage of patients requiring insulin discontinuation after initiation of incretin therapy at 6 months. Continuous variables were analyzed using paired T-tests while categorical variables were assessed with chi-square. Multivariable regression was used to adjust for potential confounders. Statistical significance was set at P < 0.05.

Results (132 words)
A total of 130 patients were included, with 65 in each treatment group. Baseline characteristics, including age, baseline HgbA1c, weight, and total daily insulin dose, were similar between groups. At six months, individuals initiating GLP-1/GIP RA therapy experienced a significantly greater reduction in total daily insulin requirements compared to those initiating GLP-1 RA therapy (35.6% vs. 28.9%, p = 0.018). Insulin therapy was fully discontinued at 6 months in 24.6% of patients in the GLP-1/GIP RA therapy group versus 16.9% of patients in the GLP-1 RA therapy group. Five patients who initiated GLP-1/GIP RA therapy required additional antihyperglycemic agents while 7 patients in the GLP-1 RA therapy group required additional agents at 6 months. No significant difference in HgbA1c at 6 months was observed between groups (-0.81% vs. -0.84%, p = 0.91).

Conclusion (97 words)
Initiation of GLP-1/GIP RA therapy resulted in a significantly greater reduction in total daily insulin requirements compared to GLP-1 RA therapy after 6 months. Additionally, a higher percentage of patients in the GLP-1/GIP RA group were able to fully discontinue insulin, while the addition of other antihyperglycemic agents was similar between groups. Despite these differences, glycemic control, as measured by HgbA1c reduction, was comparable. These findings suggest that GLP-1/GIP RA therapy may be a more effective option for reducing insulin dependence in individuals with T2DM, potentially minimizing the burden of insulin therapy and the risk of hypoglycemia.

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