c-peptide release test

The c-peptide release test was performed by the following principle. C peptide is a secreted product of islet β cells. It has a common precursor with insulin-proinsulin. One molecule of proinsulin is cleaved into one molecule of insulin and one molecule of C peptide under a special action. Therefore, in theory, C peptide and insulin are equivalently secreted, and the physiological function of free C peptide in blood is not clear. However, C-peptide is not destroyed by the liver, and its half-life is significantly longer than that of insulin. Therefore, the measurement of C-peptide levels can better reflect the function of β-cell synthesis and insulin release.