Renal Effects of DPP-4 Inhibitor Sitagliptin or GLP-1 Receptor Agonist Liraglutide in Overweight Patients With Type 2 Diabetes: A 12-Week, Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE To investigate effects of dipeptidyl peptidase-4 inhibitor (DPP-4I) sitagliptin or glucagon-like peptide 1 (GLP-1) receptor agonist liraglutide treatment on renal hemodynamics, tubular functions, and markers of renal damage in overweight patients with type 2 diabetes without chronic kidney disease (CKD). RESEARCH DESIGN AND METHODS In this 12-week, randomized, double-blind trial, 55 insulin-naive patients with type 2 diabetes (mean +/- SEM: age 63 +/- 7 years, BMI 31.8 +/- 4.1 kg/m(2), glomerular filtration rate [GFR] 83 +/- 16 mL/min/1.73 m(2); median [interquartile range]: albumin-to-creatinine ratio (ACR) 1.09 mg/mmol [0.47-3.31]) received sitagliptin (100 mg/day), liraglutide (1.8 mg/day), or matching placebos. GFR (primary end point) and effective renal plasma flow (ERPF) were determined by inulin and paraaminohippuric acid clearance, respectively. Intrarenal hemodynamic variables were estimated. Absolute and fractional excretions of sodium (FENa), potassium, and urea (FEU) and renal damage markers (ACR, neutrophil gelatinase associated lipocalin [NGAL], and kidney injury molecule-1 [KIM-1]) were measured. Plasma renin concentration (PRC) and glycated hemoglobin (HbA(1c)) were assessed. At weeks 2 and 6, estimated GFR and fractional electrolyte excretions were determined. RESULTS At week 12, GFR was not affected by sitagliptin (-6 mL/min/1.73 m(2) [95% CI 14 to 3], P = 0.17) or liraglutide (+3 mL/min/1.73 m(2) [-5 to 11], P = 0.46), compared with placebo. Sitagliptin modestly reduced estimated glomerular hydraulic pressure (P-GLO; P = 0.043). ERPF, other intrarenal hemodynamic variables, renal damage markers, and PRC did not change for both treatments. Both agents reduced HbA(1c). Only at week 2, sitagliptin increased FENa and FEU (P = 0.005). CONCLUSIONS Twelve-week treatment with sitagliptin or liraglutide does not affect measured renal hemodynamics. No sustained changes in tubular functions or alteration in renal damage markers were observed. The validity and clinical relevance of the slight sitagliptin-induced PGLo reduction remains speculative.