Real-World Patterns of Basal Insulin Use with Other Diabetes Medications Among People with Type 2 Diabetes Between 2014 and 2020

Introduction: Basal insulin's position in the type 2 diabetes (T2D) treatment paradigm has undergone significant revisions since the advent of diabetes medications such as glucagon-like peptide 1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT-2is), which offer cardiorenal protection for people with T2D (PwT2D). This study aimed to characterize the demographic, clinical, and diabetes medication utilization patterns of PwT2D initiating basal insulin between 2014 and 2020 over the time period when these revisions were occurring.

Methods: A retrospective study was conducted using the IBM MarketScan databases and included adults with T2D who initiated basal insulin therapy (basal insulin initiators) in 2015, 2017, or 2019. Patient characteristics, medication utilization patterns, and time to add an additional diabetes drug class were compared across years. Characteristics of users of basal insulin-GLP-1RA combination therapy (GLP-1RA-basal insulin dual users) were also compared across years.

Results: Between 2015 and 2019, initiation of basal insulin therapy remained steady, with 1.6-1.9% of PwT2D starting basal insulin in each year. GLP-1RA and SGLT-2i use increased pre- and post-basal insulin initiation (pre-basal: GLP-1RA, from 14.8% to 25.2%, p < 0.0001; SGLT-2i, from 11.4% to 20.5%, p < 0.0001; post-basal: GLP-1RA, from 16.7% to 30.5%, p < 0.0001; SGLT-2i, from 13.4% to 23.3%, p < 0.0001]). The proportion of PwT2D with underlying cardiovascular and renal diseases did not increase during this period. Among basal insulin initiators without prior GLP-1RA, SGLT-2i, or bolus insulin use, time to adding on these agents decreased, with 14.0-15.6% starting bolus insulin within the first year. Among GLP-1RA-basal insulin dual initiators, the proportion of those with underlying cardiovascular disease was not higher among GLP-1RA first users.

Conclusions: In this real-world study, insulin remained key in the T2D treatment paradigm. A growing proportion of PwT2D utilized GLP-1RAs and SGLT-2is before and after initiation of basal insulin therapy. At the same time, there was no increase in the proportion of those initiating basal insulin who had cardiorenal comorbidity profiles for which treatment guidelines have recommended the use of GLP-1RAs or SGLT-2is.