Outcome of the glucagon test depends upon the prevailing blood glucose concentration in type I (insulin-dependent) diabetic patients.

The outcome of 97 paired glucagon and meal tests was related to the prevailing fasting blood glucose concentrations on the two test days. At blood glucose concentration less than 7 mmol/l both the C-peptide responses and the maximal (6 min) C-peptide concentrations during the glucagon tests were significantly lower than the corresponding values found during the meal tests. During the glucagon tests, a direct relationship was found between the responsiveness of the pancreatic beta-cells and fasting blood glucose values when these were between 3 and 7 mmol/l. No significant difference was found between the outcome of the two tests when the fasting blood glucose concentration was greater than 7 mmol/l. The results indicate that the outcome of the glucagon test in Type I patients depends upon the prevailing fasting blood glucose concentration and that the predictive value of the glucagon test as to how the beta-cells will respond to a meal during everyday life is low when fasting blood glucose is less than 7 mmol/l.