Renoprotective Effects of Additional SGLT2 inhibitor Therapy in Patients With Type 2 Diabetes Mellitus and Chronic Kidney Disease Stages 3b-4: A Real World Report From A Japanese Specialized Diabetes Care Center

BACKGROUND: Large randomized clinical trials of patients with type 2 diabetes mellitus (T2DM) and at high risk for cardiovascular disease revealed that sodium-glucose cotransporter 2 (SGLT2) inhibitors significantly reduced renal events. However, the trials included small numbers of patients with moderate-to-severe chronic kidney disease (CKD). Therefore, the renoprotective effects of SGLT2 inhibitors remain unknown in T2DM patients complicated with impaired renal function. We examined if SGLT2 inhibitors conferred beneficial effects on kidney function in T2DM patients with CKD. METHODS: We retrospectively recruited T2DM patients who were newly treated with add-on of SGLT2 inhibitors and suffered from moderate-to-severe renal impairment with CKD stages 3b-4 (15 < estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m(2)), at initiation of SGLT2 inhibitor therapy. We analyzed T2DM patients with moderate-to-severe renal impairment who continued to use SGLT2 inhibitors for at least 1 year. We investigated the effects of SGLT2 inhibitor therapy on 1-year changes in eGFR and urinary protein excretion before and after the treatment. RESULTS: We analyzed 42 T2DM patients with median eGFR of 40.4 mL/min/1.73 m(2). One-year SGLT2 inhibitor therapy lowered median hemoglobin A1c (HbA1c) levels from 7.6% to 7.5% (not significant). Body weight and blood pressure were significantly decreased, and hemoglobin was significantly increased. The median value of eGFR after 1 year of SGLT2 inhibitor therapy was 41.0 mL/min/1.73 m(2), with no significant difference compared with baseline. The annual decline in eGFR improved significantly after SGLT2 inhibitor therapy (eGFR: (median), pre: -3.8, vs. post: 0.1 mL/min/1.73 m(2) per year, P < 0.01). We also found a significant decrease in urinary protein excretion after SGLT2 inhibitor therapy (urinary protein-to-creatinine ratio: (median), pre: 0.36, vs. post: 0.23 g/g creatinine, n = 35, P < 0.01). CONCLUSIONS: This study revealed the promising observations that add-on treatment with SGLT2 inhibitors exerted significant renoprotective effects, culminating in improvements in annual decline in eGFR and urinary protein excretion in T2DM patients with CKD stages 3b-4, but did not significantly reduce HbA1c. Further prospective clinical trials are warranted to fully elucidate the effects of SGLT2 inhibitors on glycemic control and renal function in T2DM patients with moderate-to-severe renal impairment.