Single Point Insulin Sensitivity Estimator (SPISE) index was recently introduced as a reliable indirect indicator of insulin resistance, applicable to large population-based research. Here, we aimed to 1) examine racial/ethnic differences in SPISE index among US adults, 2) compare predictive power of SPISE index for metabolic syndrome (MetSyn) by race/ethnicity, and 3) evaluate its predictive power for MetSyn against other well-known IR indices including Triglyceride/HDL-C, Triglyceride-glucose index, homeostatic model assessment for insulin resistance, and inverse fasting insulin.

A total of 2168 adults (814 white, 690 black, and 664 Hispanic) from NHANES 2017-March 2020 Pre-Pandemic Data was analyzed in this study. MetSyn was defined by the AHA/NHLBI criteria. SPISE index and insulin resistance indices were calculated by using physical and cardiometabolic parameters.

SPISE index was lowest in Hispanic, followed by black and white, with no difference between white vs. black. The area under the curve of receiver operating characteristics of SPISE index for predicting MetSyn was highest in white (88 %), followed by Hispanic (86 %) and black (82 %) (P < 0.05 vs. black), with optimal cutoffs of 5.03, 4.84, and 4.89, respectively. In the total cohort, the predictive power of the SPISE index for MetSyn was 85 %, higher than the other insulin resistance indices (all P < 0.05).

SPISE index outperforms various insulin resistance indices for predicting MetSyn in US adults, signifying its potential in large-scale observational studies. Race/ethnicity should be stratified when using the SPISE index as its predictive power and cutoffs for predicting MetSyn vary by race/ethnicity.