The effect of sodium-glucose cotransporter 2 inhibitor (tofogliflozin) on renal tubular damage in diabetic patients without albuminuria.

Purpose: The sodium-glucose cotransporter 2 (SGLT2) inhibitors comprise a new class of glucose-lowering drugs for individuals with diabetes. Large-scale clinical trials indicated that SGLT2 inhibitors have both a cardiovascular-protective and renal-protective effects. A reduction in glomerular hyperfiltration and a decrease in albuminuria are suspected as the main causes of SGLT2 inhibitors' renoprotective effect. The effects of SGLT2 inhibitors on tubular damage in non-albuminuric diabetic patients are unclear.

Methods: The SGLT2 inhibitor tofogliflozin (20 mg, 1 × /day) was orally administered to 14 non-albuminuric diabetic patients. Serum and urine samples were collected at baseline (before) and after the start of tofogliflozin treatment. Hemoglobin A1c, hemoglobin, estimated glomerular filtration rate (eGFR), body weight, and blood pressure (BP) were analyzed as clinical parameters at baseline and 1, 3, and 6 months later. Urinary neutrophil gelatinase-associated lipocalin (NGAL) and N-acetyl-β-D-glucosaminidase were measured as tubular damage markers and the urinary 8-hidroxydeoxyguanosine (8-OHdG) values were measured as an oxidative stress marker at baseline and at 1 and 3 months.

Results: Compared to baseline, the patients' HbA1c values and body weights were significantly decreased post-tofogliflozin administration, and their eGFR values were decreased at 3 months but recovered at 6 months; the hemoglobin concentrations were significantly increased at 3 and 6 months and the urinary NGAL level tended to be decreased at 3 months. No significant changes in blood urea nitrogen, BP, NAG, urine sodium concentration, or urinary 8-OHdG values occurred. The effect of this SGLT2 inhibitor was not influenced by the use of an angiotensin receptor blocker or dipeptidyl-peptidase 4 inhibitor.

Conclusion: For individuals with non-albuminuric diabetes, tofogliflozin has a good glucose-lowering effect and might have a tubular-protective effect.