Treatment with growth hormone may accelerate the development of type 2 diabetes in predisposed children and adolescents, say researchers.
A retrospective analysis of a Pharmacia and Upjohn database that monitors the safety of growth hormone therapy in children and adolescents was conducted by Dr Wayne Cutfield (department of paediatrics, University of Auckland, New Zealand) and colleagues. Of 23,333 children, 43 were found to have a confirmed glucose disorder - diabetes type 1 or 2, or impaired glucose tolerance. Of these, the incidence of type 2 diabetes was found to be six times greater than expected, with 18 children affected. However, the incidence of type 1 diabetes was not higher than expected.
In children who developed type 2 diabetes, the condition continued after discontinuation of growth hormone therapy, which excluded a transient drug-induced effect, the researchers say. Dr Cutfield et al comment that growth hormone is known to contribute to insulin resistance and that there are several sites in the insulin-signalling pathway at which growth hormone could induce anti-insulin effects. However, they say: "We speculate that conventional growth hormone therapy alone is unlikely to initiate a new case of diabetes mellitus." Some children receiving growth hormone may be at a higher risk of developing diabetes because they have other conditions, such as Turner's syndrome, they suggest.
The researchers advise that, before growth hormone therapy is begun, a child's glucose status should be measured and the patient should be followed up (Lancet 2000;355:610).
In a leading article commenting on the paper (ibid, p589), Dr William Jeffcoate (department of diabetes and endocrinology, City hospital, Nottingham) discusses the relevance to adults receiving treatment with growth hormone. He says that the results cannot be directly extrapolated. Much larger doses of growth hormone are used in children, he says, so the risk of diabetes in adults could be even less than that reported in the study. However, there is still "cause for concern". Dr Jeffcoate says that a large-scale, long-term, prospective study is needed to determine the efficacy and safety of growth hormone therapy.