Results of numerous clinical trials have demonstrated that, in addition to glucose-lowering properties, newer second-line diabetes medications (glucagon-like peptide-1 receptor agonists [GLP-1RAs] and sodium-glucose cotransporter-2 [sGLT2] inhibitors) have cardiovascular and renal protective effects. Trials of cardiovascular outcomes have shown marked improvement in cardiovascular and renal outcomes with SGLT2 inhibitors and GLP-1RAs. Use of those agents reduced the risks of hospital admission due to congestive heart failure, mortality from cardiovascualr disease, and major adverse atherosclerotic cardiovascular disease, as well as the incidence and progression of chronic kidney disease (CKD).
Metformin is the preferred first-line agent for the treatment of most patients with type 2 diabetes mellitus. Clinical guidelines now advise the use of the newer second-line diabetes medications in patients with clinically established cardiovascular disease independent of glycated hemoglobin levels. According to Deborah O. Ogunsanmi, BPharm, and colleagues, despite strong evidence of benefits, there are few data available regarding prescribing patterns for SGLT2 inhibitors and GLP-1RAs, particularly among patient populations at high risk for disparities.
The researchers conducted a retrospective cohort study to examine the associations of cardio-renal and obesity comorbidities and neighborhood factors of prescribing factors of newer second-line diabetes medications compared with older second-line medications (dipeptidyl peptidase 4 inhibitors [DPP-4is] or sulfonylureas [SFUs] among patients with diabetes mellitus type 2 treated with metformin in medically underserved populations at high risk for disparities. Results were reported in the Journal of Managed Care Pharmacy [2023;29(6):699-711].
The study utilized data from three large secondary databases: (1) the Tennessee Population Health Data Network (TN-POPnet); (2) IPUMS National Historical Geographic Information Systems (NHGIS) database; and (3) Centers for Medicare & Medicaid (CMS) database. TN-POPnet includes electronic medical records data from a large health care delivery system, including five adult hospitals and more than 50 outpatient clinics. The system serves medically underserved populations in the Memphis metropolitan statistical area in the Mid-South region of the United States.
The researchers obtained patient-level data from January 2016 to August 2021 from TN-POPnet. Census tract-level data for 2016-2020 were extracted from the IPOMS NHGIS database. Zip-code level data on health professional shortage area (HPSA) designations were extracted from the CMS database of HPSA. Multilevel logistic regression models were used to examine the associations of comorbidities and neighborhood factors with the prescription of newer second-line diabetes medications.
A total of 7223 patients residing in 763 distinct census tracts and 196 zip codes met eligibility criteria. Of those, 45.0% (n=3477) were prescribed SFUs, and 28.1% (n=2168) were prescribed DPP-4is, compared with 15.8% (n=1223) who were prescribed GLP-1RAs and 11.1% (n=855) who were prescribed SGLT2 inhibitors. On average, patients who were prescribed newer second-line diabetes medications (GLP-1RAs or SGLT2 inhibitors) were younger than those who received older second-line medications (DPP-4is or SFUs); (57.9 years vs 64.4 years).
The overall study cohort included more women than men, as did each of the newer (57.4%) and older (52.2%) second-line diabetes medication study groups. The overall study cohort also included more Black patients, as did each of the newer (52.2%) and older (53.9%) second-line medication study groups.
Following adjustment for patient demographics and patient clustering, results of multilevel logistic regression models showed that patients with cerebrovascular disease were significantly less likely to be prescribed newer second-line diabetes medications (odds ratio [OR], 0.65; 95% CI, 0.52-0.80). Those with obesity were more likely to be prescribed newer second-line diabetes medications (OR, 1.68; 95% CI, 1.48-1.90). There were no statistically significant associations between prescription of the newer medications and coronary artery disease, congestive heart failure, and CKD.
In analyses of neighborhood factors, patients living in census tracts with higher levels of those with bachelor’s degrees (quartiles 3 and 4) had significantly higher odds of receiving newer second-line medications for diabetes compared with those living in census tracts with the lowest levels of those with bachelor’s degrees (quartile 3 vs quartile 1: OR, 1.30; 95% CI, 1.06-1.59; and quartile 4 vs quartile 1: OR, 1.46; 95% CI, 1.13-1.88). There were no significant associations between living in HPSAs and poverty levels with the likelihood of being prescribed newer second-line diabetes medications.
The odds of being prescribed newer second-line diabetes medications decreased with increasing age, women were more likely to be prescribed newer medications than men, and all non-White racial groups were less likely to receive newer second-line diabetes mediations.
In a subanalysis of prescription of GLP-1RA versus DPP41, patients with cerebrovascular disease and congestive heart failure were significantly less likely to receive GLP-1RAs (P<.05). Those with obesity were more likely to receive GLP-1RAs (P<.05). Those living in areas with higher levels of college graduates and in zip codes designated HPSAs were more likely to receive GLP-1RAs (P<.05). In subanalysis of GLP-1RA versus SFU, those with cardiovascualr disease and coronary artery disease were significantly less likely to receive GLP-1RAs (P<.05) and those with CKD and obesity were more likely to receive GLP-1RAs (P<.05).
Study limitations cited by the authors included the inability to ascertain the actual patient use of medications, and measuring socioeconomic factors at the census tract level.
In summary, the researchers said, “We found suboptimal prescriptions of GLP-1RAs and SGLT2 inhibitors in comparison with older second-line diabetes medications. Patients with cerebrovascular comorbidities were less likely to be prescribed newer second-line diabetes medications, and patients with obesity were more likely to be prescribed these diabetes medications. Furthermore, patients living in neighborhoods with higher education levels were more likely to receive newer second-line diabetes mediations. Future studies are needed to understand barriers to prescribing newer diabetes medications to address the inequalities in diabetes care. Our findings are important for policymakers and providers and can help improve care delivery among socioeconomically disadvantaged populations with diabetes.”
Takeaway Points
- Newer second-line diabetes medications have been shown to confer cardiovascular and renal benefits to patients with type 2 diabetes mellitus.
- Researchers reported results of a study examining the associations of neighborhood factors and comorbidities with the prescription of those medications.
- Analyses revealed substantial underprescribing of the newer second-line diabetes mediations as well as significant clinical and neighborhood variation in the use of the newer second-line diabetes medications.
