Serum Retinol-Binding Protein 4: Relationship to Obesity and Type 2 Diabetes Mellitus

Abstract

Diabetes mellitus is a chronic metabolic disease characterized by hyperglycemia resulting from defects in insulin secretion as in type1 diabetes mellitus, or resistance to insulin action or both as in type 2 diabetes mellitus. Diabetes mellitus has a high mortality rate due to its complications. Most diabetic complications arise from damage to blood vessels that affect either small blood vessels (microvascular complications) or large blood vessels (macrovascular complications). Diabetic nephropathy is considered as the most common and serious microvascular complication which leads to end-stage renal disease. It is recorded in approximately one third of patients with diabetes. Obesity is a disease in which excess body fat has accumulated to such an extent that health may be negatively affected. It is commonly defined as a body mass index (weight divided by height squared) of 30 kg/m2 or higher. Many studies show an association between excessive body weight and various diseases, particularly type 2 diabetes mellitus. Besides lipid accumulation and free fatty acids (FFA) release, adipocytes together with other adipose tissue cells produce and release multiple signaling proteins termed adipokines. RBP4 was recently discussed as a new adipokine that could be linked to obesity and impaired glucose metabolism. Summary ? g 130 In order to study the association between serum levels of retinol-binding protein 4 (RBP4) and the presence of obesity and type 2 diabetes mellitus, as well as its evaluation as a risk factor for diabetic nephropathy, serum levels of RBP4 were measured in forty adult diabetic patients (fifteen lean diabetic patients and twenty-five obese diabetic patients); twenty adult obese non- diabetic patients and fifteen apparently healthy age - and sex-matched subjects serving as a control group. Diabetic patients were additionally classified according to their albumin/ creatinine ratio into sixteen diabetic normoalbuminuric patients, thirteen diabetic microalbuminuric patients and eleven diabetic macroalbuminuric patients. Assay of serum RBP4 was carried out using an enzyme-linked immunosorbent assay (ELISA) technique. The results of the present study showed a highly