Insulin I-131 Binding in Serum from Normal and Diabetic Subjects by Ultracentrifugation and Gel Filtration

Abstract

Ultracentrifugation and gel filtration were used to test for specific insulin-I-131 binding protein in the serum of normal subjects and in patients with overt or potential diabetes. Such technics permit study of sera at physiologic pH, with physiologic concentrations of exogenous insulin added. They also eliminate the interference of electrical fields and, in ultracentrifugation, the need for artificial supporting media. Whereas a specific binding protein was readily demonstrable in the serum of insulin-treated patients with high antibody titers, there was no evidence of a protein capable of binding exogenous labeled insulin in normal subjects nor in the serum of subjects with various types of diabetes and potential diabetes. Serum from subjects who have a hyper-response of insulin to glucose loads, possibly caused by peripheral antagonism to insulin action, did not bind significant amounts of insulin-I-131.