Feb. 18, 2000 (New York) -- Children who are given growth-hormone injections may be at a significantly increased risk of developing type 2 diabetes, according to a report in Saturday's issue of the journal The Lancet. Growth hormone is often prescribed for children whose pituitary glands do not make amounts of the hormone sufficient for normal growth. However, its use becomes controversial when it is given to children who are merely short-statured in order to boost their growth.
The New Zealand investigators say that the hormone injections may trigger early onset of diabetes in children who are already at risk of developing the disease later in life.
Type 2 diabetes develops when the cells in the body become resistant to the effects of insulin, the hormone that allows the blood sugar, or glucose, to be taken up into the cells and used for energy. This, in turn, leads to an accumulation of glucose in the blood. Type 2 diabetes is usually treated with diet and exercise, and in some cases, pills. Occasionally insulin injections are used if previous treatments do not control the blood sugar.
"We have always been worried about growth hormone exacerbating insulin resistance, and this is more evidence," says Allison Goldfine, MD, an investigator at Joslin Diabetes Center in Boston. "[The finding] stresses the importance of screening before giving growth hormone to identify glucose status and possibly monitoring periodically."
But Goldfine tells WebMD that it's important to put the findings into perspective, considering the psychological impact of withholding or refusing growth hormone to a child with severe growth retardation just because there is a possibility of developing diabetes.
The study included more than 20,000 Japanese children and adolescents age 19 and younger who were treated with growth hormone injections for an average of nearly three years. The average age at the start of growth hormone therapy was 10 years. Most children received growth hormone for less than three years.
Overall, the risk of diabetes was six times higher for the children who took growth hormone compared with the incidence in healthy U.S. and Japanese children not taking the hormone.
The authors say several possible explanations could account for the high incidence of type 2 diabetes reported in the study. "Although type 2 diabetes mellitus is thought to be rare in childhood and adolescence, there has been a substantial increase in the incidence of this disorder in the past few years," writes Wayne S. Cutfield, MD, a pediatric endocrinologist at the University of Auckland.
Another possibility is that the growth hormone may have hastened the onset of type 2 diabetes that would have occurred in adult life even if the children had not taken the hormone.
Stephen Gitelman, MD, director of the pediatric diabetes program at the University of California in San Francisco, says the findings are not overly surprising.
"We're seeing a real surge in type 2 diabetes in adolescents," Gitelman tells WebMD. "It's really reaching epidemic proportions. So we have this background where children are at increased risk as a result of ethnic diversity in our country and increased obesity, increased sedentary lifestyle, etc. And then on top of that you give a drug known to influence [glucose] metabolism and exacerbate insulin resistance. Given that background, it's not surprising that you are going to see a tendency toward more kids with diabetes."
But Gitelman says the possibility of diabetes developing during growth hormone treatment should always be discussed with parents, and if diabetes does develop, the shots either can be discontinued or the doses can be adjusted so as not to interfere with the diabetes.
- Growth hormone treatments are prescribed to children whose pituitary glands do not make enough of the hormone for normal growth, but some uses of the medication are controversial.
- A new study shows that children taking growth hormone are six times as likely to develop type 2 diabetes, when compared to healthy children not taking the hormone.
- Experts are unsure what to make of these findings, as many of these children are already at risk of developing type 2 diabetes and the growth hormone may serve only to hasten its onset.