We aimed to: (1) evaluate the predictive performance of polygenic risk scores (PRSs) for glycaemic traits from childhood to early adulthood; (2) identify gene-environment interactions shaping glucose homeostasis trajectories; and (3) explore underlying mechanisms using pathway-specific PRSs.<h4>Methods</h4>Data from 8783 participants (aged 7-24 years) from the Avon Longitudinal Study of Parents and Children (ALSPAC) were used to compute 12 PRSs for type 2 diabetes, fasting glucose, insulin and BMI. The gene discussed is INS; the disease is type 2 diabetes mellitus.