How much variance in insulin resistance is explained by obesity?

Abstract

Background: Obesity is believed to be the major cause of insulin resistance, although many other obesity-independent signals are shown to affect insulin sensitivity.Aim: We address the degree to which variation in insulin resistance is explained by morphometric and biochemical measures of obesity.Methods: PubMed and Google Scholar were searched for epidemiological studies published between 1994 and 2015 that report correlations between at least one measure of obesity and that of insulin resistance.Results: A total of 63 studies satisfied inclusion criteria. Frequency distribution of coefficients of determination between morphometric measures of obesity and insulin resistance was skewed with the mode being less than 10%, class and median being 17.3%. Plasma leptin concentration, but not plasma non-esterified fatty acid level, was better correlated with insulin resistance, the median variance explained being 33.29%. Morphometric measures alone had a median variance explained of 16%. Ethnicity explained part of the variance across studies with the correlation being significantly poorer in Asians.Conclusion: The extremely limited predictive power of morphometric and biochemical measures of obesity suggests that more research needs to focus on the obesity-independent signals that affect insulin sensitivity as well as leptin expression.