Insulin is the only hormone in the body that can lower blood glucose, and when a patient has an abnormal glucose measurement, the physician will recommend that the patient test for insulin function. Insulin function testing is mainly used to diagnose diabetes, and its test indicators are mainly insulin release, C-peptide secretion, and blood glucose. The method is as follows: in the morning on an empty stomach, eat 75g of glucose or 100g of plain white flour buns, and draw venous blood on an empty stomach, 1 hour, 2 hours and 3 hours after a meal, respectively, to measure blood glucose, insulin release and C-peptide secretion at four time points. The range of results for the above three indicators should be as follows: blood glucose (mmol/L): 3.9-6.1, 6.7-9.4, ≤7.8, ≤6.1, near fasting;
Insulin (uU/ml): normal value of fasting insulin is 5-20, peaking 30-60 minutes after meal, and the highest value should be between 5-10 times fasting, near fasting after 3 hours.
C-peptide (ng/ml): 0.3-0.68 in fasting, peaking at 30-60 minutes, with a peak of 5-6 times the fasting level, and close to normal after 3 hours.
Insulin release and C-peptide secretion are mainly observed at the location of the peak. If the index is abnormally elevated or the peak is delayed, it indicates poor insulin function, suggesting diabetes mellitus, and prompt consultation with internal medicine to guide treatment.