Our study demonstrated the MIDD patients with most mutations had the following clinical characteristics: (1) high incidence of progressive neurosensory deafness (85.71%); (2) early onset of diabetes and deafness; (3) high incidence of maternal inheritance (84.51%); (4) thin and short stature (41.58%); (5) absence of diabetes antibodies (90.00%); (6) progressive insulin secretory defect. Here, INS is linked to maternally-inherited diabetes and deafness.