[Effect of recombinant human growth hormone on glucose metabolism in children with growth hormone deficiency].

OBJECTIVE: Numerous studies in children with growth hormone deficiency (GHD) show that recombinant human growth hormone (rhGH) treatment results in significant catch-up growth, but some papers reported that the children who underwent rhGH therapy might be at increased risk of diabetes. The aim of this study was to investigate the effects of rhGH treatment on blood glucose and insulin metabolism in children with GHD and the relationship between growth hormone (GH) and glucose homeostasis.

METHODS: In this study, 44 children with GHD treated with rhGH [0.1 U/(kgxd)] and age- and sex-matched 20 healthy children were enrolled. The GHD group included 28 males and 16 females aged from 4.5 to 16.5 years (mean 10.4 +/- 2.6 years), including 18 cases of complete GHD and 26 cases of partial GHD. The sexual development stage of all subjects was in Tanner I. Oral glucose tolerance tests (OGTT) were done, and body mass index (BMI), serum insulin-like growth factor-1 (IGF-1) level and insulin resistance by homeostasis model (HOMA-IR) were measured at the time of diagnosis and every 3 months after rhGH therapy. Continuous glucose monitoring system (CGMS) was applied for two cases with hyperglycemia.

RESULTS: (1) Fasting glucose and IGF-1 levels increased since 3 months of treatment and did not decrease since then. The levels of fasting glucose and IGF-1 at every time points of rhGH therapy were higher than the levels at the time of diagnosis (F = 6.81, P < 0.01; F = 7.31, P < 0.01, respectively). HOMA-IR and fasting insulin levels were increased since 3 and 9 months of treatment (P = 0.001 and P = 0.021, respectively). They decreased after 12 months of therapy and the levels at 18 months of therapy were similar to that at diagnosis. (2) Pearson correlation analysis showed that HOMA-IR was positively correlated with BMI, IGF-1 and the duration of treatment (r = 0.251, 0.437, 0.281, P < 0.01, respectively). The curve between HOMA-IR and duration of therapy was similar with parabola and the quadratic equation obtained was as follows: HOMA-IR = 1.5048 + 0.2177 x duration of therapy (months)-0.0103 x duration of therapy (months)(2) (r(2) = 0.147, F = 14.16, P < 0.01). (3) Two cases had transitory hyperglycemia. Their fasting glucose levels were all higher than 7.1 mmol/L. The glucose levels returned to normal after 1 month and 5 days respectively. OGTT and CGMS showed that their plasma glucose levels were normal after rhGH therapy was applied again.

CONCLUSION: The children who underwent rhGH therapy may be at increased risk of insulin resistance (especially during the first year) and the therapy may even induce transitory glucose metabolic disorder in a very small proportion of patients. Circulating IGF-1 may participate in the control of insulin sensitivity and play an important role in the hormonal balance between GH and insulin. It may be necessary to monitor glucose metabolism and IGF-1 for all children who are treated with rhGH therapy.