Effects of ghrelin, growth hormone releasing peptide-6, and growth hormone releasing hormone on growth hormone, adrenocorticotropic hormone, and cortisol release in type 1 diabetes mellitus

Abstract

In type I diabetes mellitus (T1DM), growth hormone (GH) responses to provocative stimuli are normal or exaggerated, whereas the hypothalamic-pituitary-adrenal axis has been less studied. Ghrelin is a GH secretagogue that also increases adrenocorticotropic hormone (ACTH) and cortisol levels, similarly to GH-releasing peptide-6 (GHRP-6). Ghrelin's effects in patients with T1DM have not been evaluated. We therefore studied OH, ACTH, and cortisol responses to ghrelin and GHRP-6 in 9 patients with T1DM and 9 control subjects. the GH-releasing hormone (GHRH) induced GH release was also evaluated. Mean fasting GH levels (micrograms per liter) were higher in T1DM (3.5 +/- 1.2) than in controls (0.6 +/- 0.3). in both groups, ghrelin-induced GH release was higher than that after GHRP-6 and GHRH. When analyzing A area under the curve (Delta AUC) GH values after ghrelin, GHRP-6, and GHRH, no significant differences were observed in T1DM compared with controls. There was a trend (P = .055) to higher mean basal cortisol values (micrograms per deciliter) in T1DM (11.7 +/- 1.5) compared with controls (8.2 +/- 0.8). No significant differences were seen in Delta AUC cortisol values in both groups after ghrelin and GHRP-6. Mean fasting ACTH values were similar in T1DM and controls. No differences were seen in Delta AUC ACTH levels in both groups after ghrelin and GHRP-6. in summary, patients with T1DM have normal GH responsiveness to ghrelin, GHRP-6, and GHRH. the ACTH and cortisol release after ghrelin and GHRP-6 is also similar to controls. Our results suggest that chronic hyperglycemia of T1DM does not interfere with GH-, ACTH-, and cortisol-releasing mechanisms stimulated by these peptides. (C) 2010 Elsevier Inc. All rights reserved.