We measured autoantibodies to GAD (GADA), islet antigen-2 (IA-2A) and zinc transporter 8 (ZnT8A) in 242 individuals with NDM (median age diagnosed 1.8 months [IQR 0.39–2.9 months]; median age collected 4.6 months [IQR 1.8–27.6 months]; median diabetes duration 2 months [IQR 0.6–23 months]), including 75 whose NDM resulted from severe beta cell endoplasmic reticulum (ER) stress. The gene discussed is GAD1; the disease is neonatal diabetes mellitus.