Glucose Intolerance with Hypokalemia: An Increased Proportion of Circulating Proinsulin-like Component

Glucose tolerance, total plasma insulin, and the fractionated proinsulin-like and insulin component of circulating insulin have been studied in six patients with chronic diseases characterized by hypokalemia. Five of the six patients had abnormal glucose tolerance and three of the six had elevated fasting blood glucose; both abnormalities returned toward normal with potassium repletion. The five patients with abnormal glucose tolerance had lower and more delayed total insulin responses in the hypokalemic than normokalemic phase. In the basal state the pro-insulin-like component constituted from 20-65%, at 15 min after oral glucose 10-50%, and at 120 min 18-59% of the total circulating insulin. Hypokalemia represents an insulinopenic state in which the biologically less active proinsulin-like component constitutes a significant proportion of the total circulating insulin and may contribute to the abnormality in glucose tolerance.