Metabolic syndrome definition in adolescents should incorporate insulin resistance

To the editor,

I read Lee et al.'s recent article in the Annals of Pediatric Endocrinology & Metabolism with great interest [1]. The authors demonstrated that the determination of insulin resistance (IR) through age-corrected cutoff points correlates more strongly with metabolic syndrome (MS) than the use of fixed cutoff points. This article is based on another paper published by the same group in 2014 [2] that defined age-adjusted cutoff points for insulinemia and homeostasis model assessment (HOMA) in a Korean population. The approach used was similar to that employed by our research group, in which we defined cutoff points for Brazilian adolescents in a 2008 study [3] and sought to validate the data in a 2018 publication [4]. Several researchers have demonstrated the importance of using an IR indicator that is simple to obtain and clinically useful when compared to the gold standard, hyperinsulinemic-euglycemic clamp. The use of fasting insulinemia or HOMA may be appropriate, especially if corrected for age and sex, given the presence of a certain degree of physiological IR at puberty. Several groups have sought to define cutoff points appropriate for this purpose and, in parallel, have demonstrated that fasting glycemia is inadequate parameter due to the high compensatory capacity of the young pancreas.

Despite IR being the main etiology of MS, the most widely accepted and used definition of MS from the International Diabetes Federation [5] does not use criteria for defining IR, but only places fasting glycemia as one of its diagnostic criteria. The article by Lee et al. [1], as well as several others that have been published in recent years, clearly demonstrates that a suitable diagnosis of MS in adolescence needs to take into account IR. Several studies have demonstrated that fasting insulin or HOMA are appropriate indicators for this purpose. The use of fasting glycemia as a criterion can lead to delayed diagnosis of MS among many adolescents, delaying treatment and increasing the risk of early progression to diabetes and cardiovascular disease.