Growth hormone response to thyrotropin-releasing hormone in insulin-dependent diabetics with or without severe...

Plasma levels of growth hormone (GH) were determined in fifty-two non obese insulin-dependent diabetics (IDD) and in twenty eight control patients before and after the i.v. administration of 250 micrograms in thyrotropin-releasing hormone (TRH). The mean basal plasma GH level in the IDD was normal. Administration of TRH elicited a rise of GH above 6 ng/ml in 40% of the IDD whereas no elevation occurred in any control subject. The basal and post-stimulative GH levels were similar in diabetics with mild retinopathy and in diabetics without microvascular lesions. The basal and peak plasma GH levels as well as the GH increase after TRH were significantly higher in ten patients with nephropathy and severe retinopathy than in 42 IDD having no detectable renal damage. It is concluded that there is a disturbance of GH secretion in IDD. This abnormality seems to be independent of the short-term glycemic control and appears to be partially related to the presence of severe microvascular lesions. The present results do not prove a causal relationship between the abnormal GH secretion and the development of the diabetic microangiopathy as the pituitary dysfunction could also be a consequence of central microvascular lesions.