Association Between SGLT2 Inhibitor Therapy and the Incidence of Tinnitus in Patients with Type 2 Diabetes: A Retrospective Cohort Study

Background: Numerous studies have demonstrated the beneficial effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors on cardiovascular and renal outcomes in patients with heart failure and chronic kidney disease. However, whether SGLT2 inhibitors are also associated with a reduced risk of tinnitus has not been investigated. Objective: This study aimed to investigate the association between SGLT2 inhibitor therapy and the incidence of tinnitus in patients with type 2 diabetes. Methods: This retrospective cohort study was based on data from a nationally representative database of primary care practices in Germany from 2012 to 2023. Patients with type 2 diabetes who were treated with metformin and additionally received either an SGLT2 inhibitor or a dipeptidyl peptidase-4 (DPP4) inhibitor were included. Patients with a previous diagnosis of tinnitus were excluded. The primary outcome was the first tinnitus diagnosis documented by a primary care physician. The SGLT2 and DPP4 cohorts were compared for tinnitus incidence using Kaplan–Meier analysis and multivariable Cox regression. Results: 66,750 patients with SGLT2 inhibitors and 82,830 with DPP4 inhibitors were analyzed. The cumulative 5-year incidence of tinnitus was 1.9% in both groups. The multivariable regression analysis did not show a significant association between SGLT2 therapy and the occurrence of a tinnitus diagnosis (HR: 1.04; 95% CI: 0.89–1.21). Conclusion: There was no difference in tinnitus incidence between patients with SGLT2 or DPP4 inhibitors. The causes could lie in the heterogeneous, not purely vascular, etiology of tinnitus in general practitioners’ practices. Future studies should include further clinical data, including confirmed hearing impairments.