Insulin Resistance and the Cluster of Abnormalities Related to the Metabolic Syndrome Are Associated With Reduced Glomerular Filtration Rate in Patients With Type 2 Diabetes

Abstract

Because of its devastating outcomes, including end-stage renal disease and increased cardiovascular morbidity and mortality (1–3), chronic kidney disease (CKD) is a worldwide public health problem (4). Diabetes is the leading cause of end-stage renal disease in the Western world (5). Several evidences suggest that insulin resistance and the metabolic syndrome are associated with and probably contribute to reduced glomerular filtration rate (GFR) in patients with type 1 diabetes (6,7). At variance, no data are available in type 2 diabetes. The aim of this work was to investigate the role of insulin resistance and the cluster of metabolic syndrome–related (MS-r) abnormalities on kidney function in patients with type 2 diabetes. Two samples were studied. Selection criteria and clinical features of the first samples have been already published (8). Briefly, 731 type 2 diabetic patients (384 men and 347 women, age 61.4 ± 10 years, diabetes duration 10.8 ± 9 years, HbA1c [A1C] 8.2 ± 1.5%) were consecutively recruited at the Casa Sollievo della Sofferenza Institute in San Giovanni Rotondo. Standardized serum creatinine was measured by the modified kinetic Jaffe reaction. Micro- or macroalbuminuria was diagnosed when albumin-to-creatinine ratio (ACR) was ≥2.5 mg/mmol in men and 3.5 mg/mmol in women; 216 patients (29%) had macroalbuminuria. Estimated GFR was calculated with the abbreviated MDRD (Modification of Diet inRenal Disease) formula (9). CKD was defined as estimated GFR <60 ml/min per 1.73 m2. The homeostasis model assessment of insulin resistance index was calculated as fasting serum insulin …