The normal value of C-peptide is 250.0-600.0 pmol/L. C-peptide test results vary from time to time, and the specific value should be based on the results of professional tests in the hospital. C-peptide belongs to the peptide substances split out during the process of insulin secretion, which can play a role in maintaining the integrity and stability of insulin. After participating in the metabolic process of human body, C-peptide is degraded by kidney and excreted with urine. At present, the clinical judgment of diabetic patients is mainly based on the C-peptide value. If the C-peptide value is high, it can be judged that the patient has insulin resistance, and it can be considered that the insulin secretion is too much. If the C-peptide value is low, it can be judged that the patient has too little insulin secretion. Generally, if the C-peptide value is greater than 1.8 ng/ml, type 2 diabetes is considered possible, and if it is less than 0.5 ng/ml, type 1 diabetes is considered possible. The level of C-peptide value may be related to other diseases in addition to being affected by diabetes. The specific value of the test and the results of the examination, need to be based on the actual situation of the patient, and combined with a professional doctor examination for a comprehensive analysis.