Effects of Dietary Sodium and Protein Intake on Glomerular Filtration Rate in Subjects with Type 2 Diabetes Treated with Sodium-Glucose Cotransporter 2 Inhibitors

Abstract

Background: Approximately one forth of patients treated with SGLT2 inhibitors (SGLT2i) experience an acute estimated glomerular filtration rate (eGFR) reduction of more than 10% (“dippers”). High sodium and protein intake can increase intraglomerular pressure and predispose to a decline of renal function. We investigated whether measured creatinine clearance (CrCl) is a sensitive enough method to detect the initial dip of GFR and if dietary sodium and protein intake might influence the extent of the early change in GFR. Methods: 28 subjects with type 2 diabetes (T2D) were enrolled. 24h urinary samples for sodium and urea determination were collected, to estimate sodium and protein intake respectively before and 1, 3 and 6 months after SGLT2i initiation. Results: Mean CrCl was 83.23±25.52 ml/min/1.73 m2 (eGFR 67.32±16.07) and dropped by 19% at month 1 (eGFR by 6%). Dippers were 64% and 40%, according to CrCl and eGFR respectively. Exploring the potential correlation between changes in renal function and salt intake, ΔCrCl and baseline urinary sodium were inversely related at month 1 (r= -0,61; p<0.01), at month 3 (r= -0.51; p =0.01) and month 6 (r= -0,48; p<0.05). Likewise, an inverse correlation between ΔCrCl and baseline urinary urea was demonstrated at month 1 and 3 (r= -0.46; p<0.05 for both), at month 6 a similar trend was observed (r= -0.47; p=0.054). Conclusions: The present study suggests that a higher dietary sodium and protein intake may amplify the extent of early dip in GFR, as detected with measured CrCl, in diabetic patients undergoing SGLT2i treatment.