Effect of acute ghrelin administration on glycaemia and insulin levels in obese patients

Objectives: Ghrelin is a 28-amino-acid peptide, predominantly produced by the stomach. There are several studies that suggest the importance of ghrelin in obesity. However, the pancreatic endocrine response to ghrelin in obesity is unclear at present. The aim of this study was to clarify whether ghrelin administration influences glucose and insulin levels in obese patients. Patients and methods: Six obese female patients (31 +/- 3.4 year) with a BMI of 36.1 +/- 7.7 kg/m(2) were studied. Three tests were done: placebo, ghrelin (1 mu g/kg, intravenously) and growth hormone-releasing hormone (GHRH; 1 mu g/kg, iv) plus ghrelin (1 mu g/kg, iv). Blood samples were taken at appropriate intervals for determination of glucose and insulin. Statistical analyses were performed by Wilcoxon and Mann-Whitney tests. Results: Glucose (mean peak, mmol/l) level after placebo administration was 4.9 +/- 0.2. Glucose level after the administration of ghrelin was 5.1 +/- 0.2, not significantly different from the response after placebo (p = NS). Glucose level after the administration of ghrelin plus GHRH was 5.1 +/- 0.2, not significantly different from placebo (p = NS). Insulin (mean peak, mU/l) level after placebo administration was 16.1 +/- 6.1. Insulin level after the administration of ghrelin was 12.3 +/- 1.6, not significantly different from placebo (p = NS). Insulin level after the administration of ghrelin plus GHRH was 11.1 +/- 2.7, not significantly different from the response after placebo (p = NS). Conclusions: In female obese patients, we did not find significant differences in glucose or insulin levels following ghrelin or GHRH plus ghrelin administration.