Type 2 diabetes is eight and a half times more common among children in the Unites States treated with growth hormone than among kids who are not on the hormone treatment, a new study shows.

The researchers, based at the pharmaceutical company Eli Lilly, found that of more than 11,000 kids who took growth hormone, 11 were diagnosed with type 2 diabetes after treatment started, while none of them had type 2 diabetes before treatment.

An additional 26 kids had an impaired ability to process blood sugar, which is often a precursor to type 2 diabetes.

The children in the study received growth hormone for a variety of conditions, including a deficiency of the hormone, very short stature, or genetic disorders such as Prader-Willi syndrome or Turner syndrome.

All the patients at some point in their treatment took Humatrope, a growth hormone marketed by Eli Lilly.

The company has been monitoring children on the growth hormone to detect any unexpected side effects of the drug.

The study, which is published in the Journal of Clinical Endocrinology and Metabolism, did not compare the children who took growth hormone to children with similar health conditions who did not take the hormone; rather, the researchers compared them to a large group of kids in the general population.

According to the National Institutes of Health, about 8 out of every 100,000 kids aged 10 to 19 are diagnosed with type 2 diabetes each year. For comparison, the rate seen in the kids on growth hormone represents 100 out of every 100,000.

Dr. Christopher Child, the lead author of the study and a researcher at Lilly Research Center in England, told Reuters Health in an email that he was not surprised to see a larger proportion of diabetes cases among children who took growth hormone.

A previous study in 2000 found a similarly increased rate of diabetes, and the company had noted several diabetes cases in reports of potential side effects.

Growth hormone is known to interfere with the activity of insulin, the hormone that regulates blood sugar. It’s unclear whether the growth hormone treatment itself is responsible for the higher diabetes risk seen in the kids, however.

Child and his colleagues found that 10 of the 11 children with diabetes also had risk factors for the disease. These included obesity, radiation treatment from leukemia, and some of the growth conditions themselves that prompted the hormone treatment.

“Thus, the increased diabetes incidence compared to the general population may well reflect, at least in part, the known increased risk of diabetes in some of the patient groups for whom (growth hormone) treatment is currently indicated,” Child said.

In seven of the 11 diabetic children, their hyperglycemia - the high blood sugar involved in diabetes - resolved over time. In four of those seven children, it resolved after they stopped taking growth hormone.

Child said his company will continue to monitor the health of children long term following their treatment with growth hormone, including for signs of diabetes.

“We recommend closer surveillance of (growth hormone)-treated patients with pre-existing type 2 diabetes risk factors before, during and after treatment, to assess glucose metabolism and to encourage those lifestyle measures that have been shown to be effective for prevention of diabetes, such as diet and exercise,” Child said.

SOURCE: The Journal of Clinical Endocrinology and Metabolism, online April 13, 2011.