Diabetes is a group of metabolic diseases characterized by chronic blood sugar elevation. It is caused by multiple comprehensive factors, including genetic and environmental factors. Its etiology and pathogenesis have not been fully elucidated. In recent years, with the development of genetic diagnosis technology, more and more genes related to diabetes have been discovered, which provides a new research direction for clinical understanding and treatment of diabetes. Our hospital found a family with melatonin receptor 1B (MTNR1B) gene mutation and insulin receptor (INSR) gene mutation. Whether there is a correlation between the two mutation sites is still unclear, but it is worth clinical attention.