Early-life TCDD exposure had no persistent long-term effects on glucose homeostasis in chow-fed offspring, but when transferred to HFD, TCDD-exposed female offspring had a delayed onset of HFD-induced hyperglycemia, more pronounced HFD-induced hyperinsulinemia, and increase % PCNA+ β-cells compared with CO-exposed female offspring. The gene discussed is PCNA; the disease is hyperinsulinism.