Associations Between Type 2 Diabetes-Related Genetic Scores and Metabolic Traits, in Obese and Normal-Weight Youths.

Abstract

Young-onset obesity is strongly associated with the early development of type 2 diabetes (T2D). Genetic risk scores (GRSs) related to T2D might help predicting the early impairment of glucose homeostasis in obese youths. Our objective was to investigate the contributions of four GRSs (associated with: T2D [GRS-T2D], beta-cell function [GRS-β], insulin resistance [GRS-IR], and body mass index) to the variation of traits derived from oral glucose tolerance test (OGTT) in obese and normal-weight children and young adults. This was a cross-sectional association study. A total of 1076 obese children/adolescents (age = 11.4 ± 2.8 years) and 1265 normal-weight young volunteers (age = 21.1 ± 4.4 years) of European ancestry were recruited from pediatric obesity clinics and general population, respectively. Standard OGTT was the intervention in this study. Associations between GRSs and OGTT-derived traits including fasting glucose and insulin, insulinogenic index, insulin sensitivity index, disposition index (DI) and associations between GRSs and pre-diabetic conditions were measured. GRS-β significantly associated with fasting glucose (β = 0.019; P = 3.5 × 10^-4) and DI (β = -0.031; P = 8.9 × 10^-4, last quartile 18% lower than first) in obese children, and nominally associated with fasting glucose (β = 0.009; P = 0.017) and DI (β = -0.030; P = 1.1 × 10^-3, last quartile 11% lower than first) in normal-weight youths. GRS-T2D showed weaker contribution to fasting glucose and DI compared to GRS-β, in both obese and normal-weight youths. GRS associated with insulin resistance and GRS associated with body mass index did not associate with any traits. None of the GRSs associated with prediabetes, which affected only 4% of participants overall. Single nucleotide polymorphisms identified by genome-wide association studies to influence beta-cell function were associated with fasting glucose and indices of insulin secretion in youths, especially in obese children.