Validation of insulin sensitivity surrogate indices and prediction of clinical outcomes in individuals with and without impaired renal function

Abstract

As chronic kidney disease (CKD) progresses with abnormalities in glucose and insulin metabolism, commonly used insulin sensitivity indices (ISIs) may not be applicable in individuals with CKD. Here we sought to validate surrogate ISIs against the glucose disposal rate by the gold-standard hyperinsulinemic euglycemic glucose clamp (HEGC) technique in 1074 elderly men of similar age (70 years) of whom 495 had and 579 did not have CKD (estimated glomerular filtration rate (eGFR) under 60 ml/min per 1.73 m2 (median eGFR of 46 ml/min per 1.73 m2)). All ISIs provided satisfactory (weighted κ over 0.6) estimates of the glucose disposal rate in patients with CKD. ISIs derived from oral glucose tolerance tests (OGTTs) agreed better with HEGC than those from fasting samples (higher predictive accuracy). Regardless of CKD strata, all ISIs allowed satisfactory clinical discrimination between the presence and absence of insulin resistance (glucose disposal rate under 4 mg/kg/min). We also assessed the ability of both HEGC and ISIs to predict all-cause and cardiovascular mortality during a 10-year follow-up. Neither HEGC nor ISIs independently predicted mortality. Adjustment for renal function did not materially change these associations. Thus, ISIs can be applied in individuals with moderately impaired renal function for diagnostic purposes. For research matters, OGTT-derived ISIs may be preferred. Our data do not support the hypothesis of kidney function mediating insulin sensitivity (IS)-associated outcomes nor a role for IS as a predictor of mortality. © 2014 International Society of Nephrology.