Insulin binding to erythrocyte receptors in acromegalic patients in relation to the activity of acromegaly and to concomitant diabetes mellitus.

Insulin binding to receptors on erythrocytes was studied in patients with acromegaly (n = 27) and in control subjects without any endocrine pathology, diabetes or obesity (n = 13). According to fasting serum concentration of growth hormone (GH), acromegalics were divided into two groups: A) GH less than 10 ng/ml (n = 16) and B) GH above 20 ng/ml (n = 11), in which patients were further divided into subgroups with regard to the presence or absence of diabetes. Insulin binding was decreased both in active and inactive acromegalics when compared with controls. A greater decrease was seen in active acromegaly coupled with diabetes. This was not the case of inactive hyperglycaemic acromegalics, where a compensatory increase in the affinity of "empty" receptors might account for a lack of a greater decrease in insulin binding.