Comparison of Diuretic Effects between Empagliflozin, a Sodium-Glucose Co-Transporter 2 Inhibitor With Osmotic Diuresis, and Tolvaptan, a Water Diuretic, in Two Type 2 Diabetic Patients Taking Sodium Diuretics

Abstract

Empagliflozin, one of sodium-glucose co-transporter 2 (SGLT2) inhibitors, has been demon- strated to have beneficial effects on cardiovascular morbidity and mortality in patients with type 2 diabetes at high risk for cardiovascular events. The mechanisms behind these benefits of empagliflozin are presumed to include osmotic diuresis, being rather close to water diuresis than sodium diuresis. Two cases are presented here, where distinct changes in urinary water and sodium excretion were seen immediately after replacing tolvaptan, a water diuretic, with empagliflozin. Case 1 with heart failure showed a large decrease in urinary sodium excretion with a slight decrease in urine volume. By contrast, Case 2 with nephrotic syndrome showed a large increase in urinary sodium excretion with an increase in urine volume. The differences were probably due to distinct diuretic effects of empagliflozin and tolvaptan in the presence of sodium diuretics as well as distinct pathological conditions. In addition, the amount of urine protein was reduced after the replacement in Case 2. SGLT2 inhibitors would be expected to have the potential to exert some beneficial effects other than lowering blood glucose levels by increasing urinary glucose excretion.