Insufficient insulin secretion is considered to be a defect in beta cell function. The presence of viral infections, such as rubella virus, mumps virus, and cytomegalovirus, causes beta cell damage and autoimmune tolerance, leading to insufficient insulin secretion, and chemical and dietary factors can also cause insulin impairment. beta cell function defects, abnormal mitochondrial function, and abnormal provision and consumption of tricarboxylic acid cycle carbon cause a decrease in the number of beta cells, followed by diabetes mellitus, which clinically requires symptomatic treatment.