Insulin-receptor autoantibody detected by the human placental membrane method: six patients with insulin-receptor autoantibody in japan.

Insulin-receptor antibodies were detected in six patients out of 61 diabetics from all over Japan during 1975 to 1979 using the human placental membrane method. These 61 patients were divided into three categories: (1) Those whose diabetes control needed more than 80 units of insulin a day; (2) those whose fasting IRI was higher than 50 microU/ml even with glucose intolerance; and (3) those who had hypoglycemia of unknown origin. Controls consisted of 11 serum samples from 11 healthy women and six diabetics treated with insulin and thus having insulin antibodies in their sera. The sera from healthy subjects did not suppress 125I-insulin binding with human placental membrane in either the direct or the preincubation method. 125I-insulin binding in the direct method was markedly suppressed, however, by the sera of insulin-treated diabetics, although no such suppression was observed with the preincubation method. In six of the 61 subjects (two males and four females), inhibition of binding was proved by both direct and preincubation methods for the protein fraction of the sera, particularly for the IgG fraction in five cases. Three of the six had Sjögren syndrome; one of these also had acanthosis nigricans. Four of the six showed insulin resistance, and two did not. A follow-up showed that antibodies decreased relatively quickly in three of the six cases, with the degree of inhibition paralleling patients' clinical courses.