Recent studies have suggested that insulin resistance and hyperinsulinemia exist in isolation from one another and play different pathogenic roles in cardiovascular disease (CVD). To understand how discordant insulin resistance and hyperinsulinemia are, this study quantified the percentage of individuals (n=446) in quartiles of insulin response by quartiles of insulin sensitivity. The authors also compared cardiovascular disease (CVD) risk factors in individuals within the same quartiles of insulin sensitivity but with differing insulin response levels. Results showed a significant correlation between insulin resistance and insulin response (r=0.76, p<0.001) with no difference by sex (male, r=0.77; female, r=0.76). After dividing individuals into quartiles of insulin sensitivity, the authors observed that an increase in insulin resistance was accompanied by an increase in the proportion of individuals with impaired glucose tolerance (IGT). The majority (95%) of the most insulin-resistant individuals were in the top two quartiles. Fasting plasma insulin concentrations also increased in parallel with degree of insulin resistance. Finally, the more insulin resistant the group was, the more unfavourable its CVD risk profile was. The authors concluded that insulin resistance and hyperinsulinemia are closely linked. Although insulin sensitivity does not account for 100% of the variance in insulin response, it is difficult to discern whether hyperinsulinemia has an independent impact on CVD risk factors associated with insulin resistance.
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