The patient was diagnosed with type 1 diabetes at 2 months after birth by hyperglycemia (362 mg/dL [20.1 mmol/L]; normal reference range 70-180 mg/dL [3.9-10.0 mmol/L]) and decreased endogenous insulin secretion (serum C-peptide concentration 0.2 ng/mL [0.07 nmol/L]; normal reference range 0.74-3.18 ng/mL [0.25-1.05 nmol/L] and serum immunoreactive insulin concentration < 3 μg/mL; normal reference range 1-18 μg/mL). The gene discussed is INS; the disease is type 1 diabetes mellitus.