Serum sodium ion level influenced by daily salt intake after administration of sodium-glucose cotransporter 2 inhibitors

Although sodium–glucose cotransporter 2 (SGLT2) inhibitors increase the excretion of sodium into urine, hyponatraemia is rare, consequent averse effect. In this study, we examined whether salt (sodium ion) intake affects serum sodium levels in 20 patients with type 2 diabetes mellitus after receiving SGLT2 inhibitors. The patients underwent regular follow-up examinations at one-month interval during which blood glucose, serum sodium and HbA1c levels were assessed, and daily salt intake was estimated according to Tanaka’s formula. The samples from before and after starting canagliflozin (100mg/day) were compared. The data showed significant positive correlation between the changes in serum sodium levels and daily salt intake in patients after receiving SGLT2 inhibitors. This indicates that patients who reduce their daily salt intake while under SGLT2 inhibitor medication may experience hyponatraemia. Although salt restriction is important to treat patients with type 2 diabetes mellitus and hypertension, daily salt intake should be considered carefully when SGLT2 inhibitors are administered.