The screening for coeliac disease was negative (IgA 165 mg/dl; tTG 0.4 U/mL), and an oral glucose tolerance test indicated diabetes mellitus (120’ glycaemia 234 mg/dl), with marked hyperinsulinism and insulin resistance (peak insulin level was 279 μU/mL, 120’ insulin level 167 μU/mL). The gene discussed is TGM2; the disease is hyperinsulinism.