Adiposity Impacts Intrarenal Hemodynamic Function in Adults With Long-standing Type 1 Diabetes With and Without Diabetic Nephropathy: Results From the Canadian Study of Longevity in Type 1 Diabetes.

OBJECTIVE: Central adiposity is considered to be an important cardiorenal risk factor in the general population and in type 1 diabetes. We sought to determine the relationship between central adiposity and intrarenal hemodynamic function in adults with long-standing type 1 diabetes with and without diabetic nephropathy (DN).

RESEARCH DESIGN AND METHODS: Patients with type 1 diabetes ( n = 66, duration ≥50 years) and age-/sex-matched control subjects ( n = 73) were studied. The cohort was stratified into 44 DN Resistors (estimated glomerular filtration rate [eGFR] >60 mL/min/1.73 m2 and <30 mg/day urine albumin) and 22 patients with DN (eGFR ≤60 mL/min/1.73 m2 or ≥30 mg/day urine albumin). Intrarenal hemodynamic function (glomerular filtration rate for inulin [GFRINULIN ], effective renal plasma flow for p -aminohippuric acid [ERPFPAH ]) was measured. Afferent arteriolar resistance, efferent arteriolar resistance, renal blood flow, renal vascular resistance [RVR], filtration fraction, and glomerular pressure were derived from the Gomez equations. Fat and lean mass were quantified by DXA.

RESULTS: Whereas measures of adiposity did not associate with GFRINULIN or ERPFPAH in healthy control subjects, trunk fat mass inversely correlated with GFRINULIN ( r = -0.46, P < 0.0001) and ERPFPAH ( r = -0.31, P = 0.01) and positively correlated with RVR ( r = 0.53, P = 0.0003) in type 1 diabetes. In analyses stratified by DN status, greater central adiposity related to lower GFRINULIN values in DN and DN Resistors, but the relationships between central adiposity and ERPFPAH and RVR were attenuated and/or reversed in patients with DN compared with DN Resistors.

CONCLUSIONS: The adiposity-intrarenal hemodynamic function relationship may be modified by the presence of type 1 diabetes and DN, requiring further study of the mechanisms by which adiposity influences renal hemodynamic function.