Metabolic syndrome is not a risk factor for kidney dysfunction in obese non-diabetic subjects

Objective: To investigate whether insulin resistance (IR) and the metabolic syndrome (MS) are associated with kidney dysfunction in obese non‐diabetic (OND) subjects. Methods and Procedures: Three‐hundred and eighty (113M/267F; age = 41 ± 14 years) OND subjects (BMI ≥ 30 kg/m²; range = 43 ± 8 kg/m²) were studied. Anthropometric measures, blood pressure, fasting glucose, insulin, lipid profile, and serum creatinine were evaluated. Glomerular filtration rate (GFR) was estimated (e‐GFR) with the Modification of Diet in Renal Disease equation. Chronic kidney disease (CKD) was defined as e‐GFR <60 ml/min/1.73 m². Results: e‐GFR was associated with gender (being lower in women) (P = 0.001) and age (P < 0.0001). CKD was present in 32 subjects (8.4%), who were older (P < 0.0001) and more frequently affected by hypertension (P = 0.04) as compared to subjects without CKD. MS was present in 212 (55.8%) subjects. They were older (P< 0.001), had lower e‐GFR (P = 0.02) and were more frequently affected by CKD (odds ratio (OR), 95% confidence interval (CI) = 2.3, 1.1–5.1) than those without MS. However, differences in e‐GFR values and in the risk of CKD were no longer statistically significant after adjusting for age (P = 0.99 for e‐GFR and OR, 95% CI = 1.2, 0.5–2.8 for the risk of CKD, respectively). Homeostasis model assessment of IR (HOMA_IR) index was neither higher in subject with CKD (P = 0.1) nor inversely correlated with e‐GFR (r = 0.1, P = 0.1). Discussion: In OND individuals the risk of CKD is independent of the MS and related abnormalities. This suggests that these individuals are not susceptible to a further deleterious role on kidney function on the top of that played by obesity itself.