Background: Type 2 diabetes (T2DM) disproportionally affects racial/ethnic minorities and low-income populations. New treatments with proven cardiorenal benefits like sodium-glucose cotransporter-2 inhibitors (SGLT2is) and glucagon-like peptide-1 receptor antagonists (GLP-1RAs) have shifted the treatment paradigm and are recommended by guidelines for patients with cardiorenal conditions. However, there is a lack of data on uptake of these therapies across race, ethnicity, or social determinants of health (SDoH).
Objectives: To evaluate racial, ethnic, and SDoH-related disparities in uptake of newer antidiabetic therapies among patients with T2DM and comorbid cardiorenal conditions.
Methods: This was a retrospective cohort study using a 50% sample of Medicare fee-for-service data from 2013 to 2019. Older adults (≥65 years) with T2DM initiating either SGLT2is, GLP1-RAs, dipeptidyl peptidase-4 inhibitors (DPP-4is), sulfonylureas, or thiazolidinediones were included, and categorized into three cohorts: heart failure (HF), chronic kidney disease (CKD), and atherosclerotic cardiovascular disease (ASCVD). The CDC/ATSDR Social Vulnerability Index (SVI) was used to ascertain county-level SDoH information on socioeconomic status, household composition, minority status, and housing/ transportation. Multinomial logistic regressions were used to model the probability of initiating a drug class, conditioned on age, sex, ethnicity, and SVI themes.
Results: We identified 949,592 eligible episodes of drug initiation (mean age: 74.3, 52.6% male). Black (compared to White) patients were 32.1% (95% confidence interval: 28.2, 35.8), 28.5% (26.0, 28.5), and 29.2% (24.9, 33.2) less likely to initiate SGLT2i for the indication of HF, ASCVD, and CKD. The corresponding numbers for GLP-1RAs were 21.6% (17.6, 25.4), 19.0% (16.3, 21.6), and 20.6% (16.9, 24.1), respectively. At the beginning of the study period in 2013, the underuse of SGLT2i and GLP-1RAs among Black patients in the three cohorts ranged between 39.3 to 54.1 percent; however, this difference continued to diminish over the course of the study, reaching 21.4 to 36.0 percent in 2016, and approaching parity by 2019: -0.3 to 11.5 percent. Notably, SVI themes were not found to be a major factor in initiation of SGLT2i or GLP-1RAs.
Conclusions: Among patients with cardiorenal conditions, disparities in the use of newer guideline recommended antidiabetic therapies were most evident for Black patients; however, these disparities diminished over the course of the study period. Understanding the reasons for these disparities in medication use is necessary to promote equitable management of T2DM and outcomes among older Black patients in the US.
