[Clinical usefulness of the glucagon test in the study of pancreatic islet cell function]

In an attempt to assess the utility of glucagon test as an index of beta cell function, we have studied the C-Peptide response to intravenous injection of 1 mg of glucagon in 77 patients with type I diabetes, 27 type II diabetics and 14 normal subjects. A significant difference between basal and glucagon-stimulated C-Peptide levels as well as a good relationship between both values were observed in all groups (r values 0.91, 0.80 and 0.89 respectively). Both basal and stimulated C-Peptide concentrations showed significant relationship with the body mass index and total cholesterol levels, whereas both parameters were negatively related to insulin requirements in type I diabetic group. Absolute C-Peptide increment was different in all groups, despite it was not related to basal C-Peptide levels. These findings confirm the usefulness of glucagon test as an investigative tool to assess the secretory capacity of beta-cell, suggesting that estimation of C-Peptide increment represents the best parameter to evaluate beta-cell reserve.