The value of C-peptide level measurements in diabetes mellitus

A prospective study of 27 patients with diabetes mellitus was done to assess their basal and glucagon stimulated C-peptide levels. Based on recommended cut off values for both basal and stimulated C-peptide levels, these patients were subsequently classified as insulin or non-insulin requiring diabetics. As in most other studies, we demonstrated a good correlation between the basal and glucagon stimulated C-peptide levels. Of the 8 patients on insulin therapy prior to this test, we found that only 2 actually required insulin i.e. had poor pancreatic reserve. Of the remaining 19 patients who were on diet and/or oral hypoglycaemic agents, we found that only one newly diagnosed diabetic had a definitive indication for insulin therapy. Among the other diabetics with poor control despite being on oral hypoglycaemic therapy, we found they had good islet cell secretory capacity for insulin.