Exploration of the early insulin response by two small successive loads of I.V. glucose in normal and obese subjects.

Two 5 g glucose loads at 1-h interval were given to healthy controls and obese subjects with slightly altered or normal OGTT in order to explore the capacity of restoration of the "rapid insulin response" to i.v. glucose. In the normal subjects, the two successive loads gave rise to identical responses as far as maximum increase (delta max), average increase at 2-5 min (delta 2-5 min), area of increase 0-15 min (delta 0-15 min) for both glucose and IRI, were concerned. Obese subjects could be divided on the basis of their insulin response to the first load into normal responders (group I) and high-responders (group II). In group I obese subjects, the responses to the second load were identical to those to the first. In group II obese subjects delta max, delta 2-5 min and delta 0-15 min of the insulin response to the second load were reduced as compared to the first.