Chemical and Early Overt Diabetes Mellitus in Children: II. Effect of Intravenous Tolbutamide on “Insulin Reserve”

Abstract

Blood sugar and serum immunoreactive insulin (IRI) response to a rapid intravenous infusion of tolbutamide was studied in twelve normal subjects, forty-four children with chemical diabetes and ten children with overt diabetes mellitus of recent onset. The diagnosis of chemical diabetes was based on two or more abnormal oral glucose tolerance tests, separated by at least two months' time interval. Of the forty-four children with chemical diabetes, twenty-four children had one or more blood sugar values outside the ninety-seventh or third percentile during oral glucose tolerance tests (“late” chemical diabetes) and had impaired tolbutamide responses at thirty minutes which were significantly different from normal controls and from the children with overt diabetes. Serum IRI levels were similar in chemical diabetics and normal subjects. Overt diabetics had decreased IRI responses to tolbutamide. The tolbutamide test as performed will not detect children in the earlier stages of chemical diabetes. Until a more sensitive and reliable test is devised, it is necessary to rely on repeated oral glucose tolerance tests to identify children in the earlier stages of chemical diabetes. Longitudinal studies of a large group of children with chemical diabetes are necessary in order to extend our knowledge of the pathophysiology of the disorder and to establish more specific and reliable criteria to define the stages of the disease.