Prevalence of residual B-cell function in insulin-treated diabetics evaluated by the plasma C-etide response to intravenous glucagon.

In 83 insulin-treated diabetics the influence of the duration of insulin treatment on the prevalence of residual insulin secretion was examined by determining the plasma C-peptide concentration before and after intravenous injection of 1 mg of glucagon. In 64 patients, plasma C-etide concentration was also determined before and after a standard meal. There was a good correlation between the C-peptide response to glucagon and to the meal (r = 0.67; p less than 0.0001) suggesting that the glucagon test will predict the B-cell response during everyday life. The predictive value of a positive glucagon test was 84% and of a negative test 100%. A preserved, but reduced, B-cell function was demonstrable in 36 of 83 patients. Residual B-cell function was most frequent in the patients with the shortest duration of diabetes. The metabolic importance of endogenous insulin was demonstrated by the significantly lower insulin requirement in the patients with residual B-cell function.