According to the study of UK there were 5% of the people who were diagnosed with diabetes before the age of 45 suffering from MODY, but 80% of them misdiagnosed with type 1 or type 2 diabetes mellitus, which suggested that without considering the family history of diabetes or metabolic features, all people who were diagnosed up to the age of 30 with diabetes and C-peptide ≥0.2 nmol/L should be considered for HNF1A and HNF4A genes test [8]. The gene discussed is HNF1A; the disease is MODY.