Islet function can be evaluated by the insulin release test, which measures serum insulin and serum C-peptide levels before, and 30, 60, 120, and 180 minutes after taking 75 grams of glucose, respectively, to depict the release curves of insulin and C-peptide and thus assess islet function. Insulin and C-peptide are isomolecularly secreted, and if the serum insulin level measured after insulin injection is affected by the injected insulin, the serum insulin value at that time cannot accurately assess one’s islet function, and one needs to use the serum C-peptide value to assess one’s islet function status. The normal fasting insulin level is 17.8-173pmol/L and the normal fasting c-peptide level is 0.37-1.47nmol/L. The peak of serum insulin and serum C-peptide release occurs 30-60 minutes after taking sugar, and the peak of serum insulin is 5-10 times higher than fasting, and the peak of serum C-peptide is 5-6 times higher than fasting. The islet function will continue to be tested after the self-glucose problem occurs, and the appropriate treatment should be directed by the endocrinology department as soon as the blood glucose problem occurs.