Predictors of Use of Individual Insulin and GLP-1 RA Products Versus Fixed Ratio Insulin/GLP-1 RA Combinations in Medicare Beneficiaries

<b>Background:</b> In 2022, federal law capped insulin product costs at $35 per month for Medicare prescription drug plan recipients. However, this law did not address the high costs of other antihyperglycemic medications, such as glucagon-like peptide-1 receptor agonists (GLP-1RAs), with an average copay of $120 per month. Under the law, fixed-ratio insulin/GLP-1RA combination products are classified as "insulin products," making these effective medications more accessible to patients who might otherwise be unable to afford them. Patients may not be aware of the potential financial benefits of combination products, highlighting the need to identify those using them to better educate both patients and providers. <b>Objectives:</b> The primary objective was to identify predictors of use for the insulin/GLP-1RA combinations. The secondary objective was to determine if there was a difference in medication cost to patients between individual and combination product users and determine cost savings potential of switching. <b>Design:</b> This was a retrospective, observational cohort analysis. <b>Setting:</b> Prescription fill data were examined for antihyperglycemic medications filled between January 1, 2022, and December 31, 2022. Prescriptions were filled within one regional division of a large community-based pharmacy chain, encompassing 71 pharmacies within Kansas, Nebraska, and Missouri. <b>Methods:</b> This retrospective observational cohort analysis examined prescription fill data for antihyperglycemic medications for the calendar year 2022 across one regional division of a large community-based pharmacy chain. Included patients 65 years of age or older with a Medicare prescription drug plan, using any basal insulin and any GLP-1RA, including combinations, as well as metformin, with ≥ 80% proportion of days covered. Demographics, usage predictors, and cost differences were compared between patients using individual products and those using insulin/GLP-1RA combination products. <b>Results:</b> A total of 138 patients were analyzed. The use of insulin/GLP-1RA combination products was associated with increased likelihood of using sodium-glucose cotransporter-2 inhibitors (<i>P</i> = 0.022). Median annual out-of-pocket spending was significantly different between groups (<i>P</i> < 0.001), with most combination users paying more than $1,000 less per year than individual product users. <b>Conclusion:</b> Insulin/GLP-1RA combination products represent a cost-effective alternative to individual antidiabetic pharmacotherapy agents.