Neuroendocrine responses to hypoglycaemia decrease within the first year after diagnosis of type 1 diabetes.
ABSTRACT Neuroendocrine responses (adrenaline, noradrenaline and pancreatic polypeptide (PP)) to hypoglycaemia are often diminished in long-term diabetic patients, but the role of autonomic nervous system changes in these reductions is not yet fully clarified. In order to establish whether such changes in neuroendocrine responses occur early in the course of diabetes, we investigated the responses to insulin-induced hxypoglycaemia during the first year of type 1 diabetes. Autonomic and somatic nerve function tests were performed concomitantly. Six type 1 diabetes patients were studied 3 and 12 months after diagnosis of diabetes. Hypoglycaemia was induced by i.v. insulin infusion after an overnight normalization of blood glucose. Autonomic nerve function was evaluated by cardiovascular tests, and somatic nerve function by nerve conduction velocities A 50% reduction was found in adrenaline (p < 0.025) and noradrenaline (p < 0.05) responses to hypoglycaemia; PP, too, was significantly diminished at 12 months compared with 3 months after diagnosis of type 1 diabetes. Rate of glucose recovery did not differ at month 12 compared with month 3. Cardiovascular autonomic nerve function tests did not change and remained within the normal range throughout the study. Altered neuroendocrine responses to hypoglycaemia may occur early in the course of type 1 diabetes. These are unlikely to be due to structural changes (i.e. autonomic neuropathy), but rather to changes in central nervous system activity patterns, i.e. a higher threshold (i.e. a lower blood glucose level) for hypothalamic activation of the sympathoadrenal system.
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ABSTRACT: Over the past decades, research in patients with rheumatic disorders showed enormous progress in detecting various perturbations of the neuroendocrine system including those affecting autonomic nervous function. There is, however, a substantial lack of data on adrenomedullary hormonal system (AMHS) function in those patients. Insulin-induced hypoglycemia (IIH) represents a metabolic stressor, which elicits a counterregulatory stress response not only of the hypothalamic-pituitary axis but also of the AMHS. Therefore, in addition to traditional testing of hypothalamic-pituitary function, IIH can be used as a well-controlled functional test of the AMHS. Our recent studies showed, for the first time, attenuated epinephrine and norepinephrine responses to IIH in premenopausal females with rheumatoid arthritis (RA) and systemic sclerosis (SSc). These findings are suggestive of downregulation, or possibly defects, of the AMHS in those patients. This article reviews mechanism of the AMHS activation during IIH and demonstrates applications of the test in neuroendocrine-immune research.Annals of the New York Academy of Sciences 07/2006; 1069:98-108. · 4.38 Impact Factor