Serum adiponectin is increased in type 1 diabetic patients with nephropathy

Abstract

Objective: To elucidate whether serum adiponectin is associated with renal function, low-grade inflammatory markers, metabolic control, and insulin resistance in type 1 diabetic patients with and without nephropathy.

Research design and methods: A total of 189 type 1 diabetic patients from the Finnish Diabetic Nephropathy Study were divided into three groups based on their urinary albumin excretion rate (AER): patients with normal AER (n = 66) had no antihypertensive medication, while patients with microalbuminuria (n = 63) or macroalbuminuria (n = 60) were all treated with an ACE inhibitor. Renal function was estimated with the Cockcroft-Gault formula. Adiponectin was measured by an in-house time-resolved immunofluorometric assay.

Results: Adiponectin concentrations were higher in women than in men, but since there was no significant difference in sex distribution between the groups, data were pooled. Adiponectin concentrations were higher in patients with macroalbuminuria (19.8 +/- 12.0 mg/l) than in patients with microalbuminuria (13.1 +/- 4.8 mg/l) or normoalbuminuria (11.8 +/- 4.2 mg/l). In a univariate analysis, adiponectin was positively associated with creatinine (r = 0.41; P < 0.0001), AER (r = 0.33; P < 0.0001), interleukin-6 (r = 0.22; P = 0.002), systolic blood pressure (r = 0.22; P = 0.004), HbA(1c) (r = 0.17; P = 0.02), total cholesterol (r = 0.16; P = 0.03), and HDL cholesterol (r = 0.16; P = 0.03) and negatively with estimated glomerular filtration rate (GFR; r = -0.52; P < 0.0001) and waist-to-hip ratio (WHR; r = -0.16; P = 0.03). In a multiple linear regression analysis including the above variables, estimated GFR, AER, and WHR were independently associated with adiponectin levels (r(2) = 0.32).

Conclusions: Serum adiponectin concentrations are increased in type 1 diabetic patients with nephropathy, and levels are further associated with renal insufficiency.