Validation of Steady State Insulin Sensitivity Indices in Chronic Kidney Disease

Abstract

Objective: Insulin resistance may contribute to cardiovascular disease and the progression of renal insufficiency in patients with chronic kidney disease (CKD). However, feasible methods for estimating insulin sensitivity in large-population CKD studies have not been validated. The purpose of this study was to attempt to validate several commonly used steady state insulin sensitivity indices in a CKD population.

Research design and methods: Twenty seven subjects with estimated glomerular filtration rate (eGFR) ranging from 70 to <10 ml/minute/1.73m² (median eGFR=48 ml/min/1.73m²) underwent a frequently sampled intravenous glucose tolerance test (FSIVGTT) on a single occasion. Correlations were obtained between the minimal model-derived insulin sensitivity parameter from the FSIVGTT (SI-FSIVGTT) and seven steady state insulin sensitivity indices derived from fasting insulin and glucose data obtained just prior to the FSIVGTT.

Results: Each of the seven steady state indices was significantly correlated with SI-FSIVGTT. For indices obtained using the mean of 4 fasting insulin and glucose values over 15 minutes, Pearson correlation coefficients (|r|) ranged from 0.51 to 0.87 (p<0.01 for each). For indices using single fasting insulin and glucose values, |r| ranged from 0.51 to 0.72 (p<0.01 for each). By both the four and one time point approaches, 1/I₀ had the highest correlation with SI-FSIVGTT. The correlation with SI-FSIVGTT did not change significantly according to eGFR level for any of the SI-SS indices.

Conclusions: Steady state insulin sensitivity indices are valid surrogates for SI-FSIVGTT in the CKD population. Their use will expand the range of testable hypotheses in CKD cohort studies.