Tofogliflozin reduces sleep apnea severity in patients with type 2 diabetes mellitus and heart failure: a prospective study

Sleep apnea (SA) is prevalent among patients with heart failure (HF) and contributes to a poor prognosis. Sodium–glucose cotransporter 2 (SGLT2) inhibitors have demonstrated efficacy in reducing the risk of serious clinical events in patients with HF. Additionally, SGLT2 inhibitors may reduce the risk of incident SA and mitigate its severity in patients with cardiovascular disease and T2DM. We aimed to investigate whether the SGLT2 inhibitor tofogliflozin reduced the severity of SA, as assessed using the apnea–hypopnea index (AHI), in patients with HF and T2DM and whether a decrease in AHI correlates with changes in body composition and cardiorenal function parameters. This is a single-arm, prospective pathophysiologic study involving patients with HF, T2DM, and SA, defined as having an AHI of 15 events/h and more. SA was assessed using polysomnography. Changes in AHI before and 6 months after starting oral administration of tofogliflozin (20 mg) were assessed. Additionally, body composition and cardiorenal functions were assessed before and 6 months after tofogliflozin administration. Ten patients with HF, T2DM, and SA were finally enrolled (60% men, 66.9 ± 13.4 years). Tofogliflozin reduced AHI from 43.2 [30.2] to 35.3 [13.1] events/h (p = 0.024) at 6 months. Hemoglobin A1c, body weight, and body water content decreased significantly. However, no significant changes were observed in the cardiorenal function parameters. A linear relationship was observed between the changes in body water content and AHI (r = 0.642, p = 0.045). Tofogliflozin reduced AHI, possibly associated with a reduction in body water content.