Diabetes mellitus has been a major social problem due to its prevalence, which results from a combination of peripheral insulin resistance and insufficient insulin secretion.The whole process of insulin biosynthesis, transportation, maturation and secretion is largely understood, however, detailed mechanism remains to be uncovered. We reported here a highly conserved protein, HID-1, functions during the correct processing of insulin. We generated a beta cell-specific conditional knock out mouse model of hid-1 gene. The knock out mice showed significant glucose intolerance while normal response to insulin with no significant defect in islets’ morphology. Further study revealed remarkable increase in proinsulin to insulin ratio and abnormal proinsulin accumulation, suggesting that HID-1 may function in the conversion process from proinsulin to insulin.