Response of Circulating Ghrelin Levels to Insulin Therapy in Children with Newly Diagnosed Type 1 Diabetes Mellitus

Ghrelin is secreted primarily by the stomach, although other tissues such as the pancreas synthesize a minor proportion. The discovery of a new cell type that produces ghrelin in the human pancreas and that this organ expresses GHS-R opens new perspectives in the understanding of the control of glucose metabolism. We have studied 22 children with newly diagnosed type 1 diabetes mellitus at four different points: at diagnosis before insulin therapy, after 48–60 h of insulin therapy, and after 1 and 4 mo of insulin treatment. At each point circulating levels of ghrelin, leptin, IGF-I, IGF binding protein (IGFBP)-1, IGFBP-2, IGFBP-3, and glucose were determined. Ghrelin levels were significantly decreased at diagnosis (573 ± 68 pg/mL, p < 0.01) compared with controls (867 ± 38 pg/mL) and remained decreased after insulin therapy (d 2: 595 ± 68 pg/mL; 1 mo: 590 ± 61 pg/mL; 4 mo: 538 ± 67 pg/mL) with no differences before or after insulin treatment. There was a negative correlation between ghrelin levels and body mass index at all of the study points, whereas a negative correlation between ghrelin and glucose concentrations was only observed after insulin therapy. No correlation between ghrelin and HbA1c was found at any point. A positive correlation between ghrelin and IGFBP-1 was found after insulin therapy, but no correlation with other members of the IGF system or leptin was found. In conclusion, these data could indicate a possible link between glucose concentrations and ghrelin; hence, the persisting low ghrelin levels in diabetic children may suggest a defensive mechanism against hyperglycemia.