Background: GH has been shown to influence glucose homeostasis through a negative effect on insulin sensitivity followed by a compensatory increase of insulin secretion. However it has been recently reported, in animals and in humans, that GH might stimulate insulin secretion also through a direct effect on the growth and on the function of the pancreatic β cell.
Objective and hypotheses: To study longitudinally the insulin sensitivity (HOMA-S), the insulin secretion (IGI) and the capacity of the β cell to adapt to the insulin sensitivity (oral disposition index (ODI)) in a group of girls affected by Turners syndrome (TS) and in a group of GH deficient children (GHD).
Method: We studied 92 TS (9.7±2.95 years) and 99 GHD (62 m, 37 f) (8.9±3.5 years for a median period of 7.32 years (range 2.0413) in TS and 7.7 years (range 3.414.7) in GHD). Every year the children underwent an OGTT which was employed to calculate the HOMA-S (1/((insulin×glucose)/22.5)), the insulinogenic index, IGI (ΔI30/ΔG30) and the ODI (disposition index=HOMA−S×IGI).
Results: In TS no significant changes over the years were observed in term of HOMA-S, IGI, or ODI. On the contrary, in GHD children, despite HOMA-S remaining unchanged, an increase of IGI (1.25±1.28 vs 2.35±2.38) and ODI (0.57±0.68 vs 1.23±1.68) was observed, which became significant after 6 years of treatment. There was no difference before GH treatment between GHD and TS regarding HOMA-S, IGI, and ODI but IGI became significantly higher in GHD after 6 years.
Conclusion: Our results suggest a positive influence of GH treatment on the β cell secretory capacity in children with GH deficiency, while no effect was observed in those (TS) with normal GH secretion. A different sensitivity to GH might explain the differences.
18 Sep 2014 - 20 Sep 2014