NEW YORK (Reuters Health) – Growth hormone treatment of adults isn’t associated with an increased risk of developing diabetes, according to a new report.

“The strength of the study is that it is a real world survey of the prevalence of diabetes in these patients on treatment and that it shows no significant change when compared to the untreated state,” Dr. David R. Clemmons from University of North Carolina, Chapel Hill, told Reuters Health in an email.

Dr. Clemmons and colleagues in the Hypopituitary Control and Complications International Advisory Board investigated the prevalence and incidence of diabetes among 6672 adult patients with growth hormone deficiency being treated with recombinant human growth hormone.

The study was supported by Eli Lilly and CO, who manufacture Humatrope recombinant human growth hormone.

The overall prevalence of diabetes among patients in their database was 8.2%, with rates in the United States (11.2%) that were double those in Europe (5.7%). The results appear in the May 4th online issue of The Journal of Clinical Endocrinology & Metabolism.

During 22,493 patient-years follow-up (mean follow-up time, 4.1 years), the overall incidence of diabetes was 9.7 per 1000 patient-years (14.1 in the US, 7.0 in Europe).

The incidence of diabetes assessed by body-mass index (BMI) category was comparable in the US and Europe for BMI below 25 kg/meter squared and 25-30 kg/meter squared, but almost twice as high in the US than in Europe for BMI above 30 kg/meter squared.

After adjustment for BMI, the diabetes incidence rate among US patients (10.6 per 1000 patient-years) was higher than the incidence rate of self-reported diabetes in the US general population (7.1 per 1000 patient-years).

In a proportional hazard model, however, BMI and age were the only significant predictors of diabetes mellitus incidence in Europe and the US. Gender, growth hormone dose, and history of Cushing’s disease weren’t significant predictors.

For each unit increase in BMI, the likelihood of developing diabetes increased by 7.3% for US patients and by 8.0% for European patients, irrespective of other factors.

“Our analysis suggests that increased incidence of diabetes mellitus during growth hormone replacement therapy is associated with the continuing presence of obesity and metabolic syndrome rather than growth hormone therapy per se,” the researchers conclude.

“Patients who begin treatment with a BMI>30 need to be carefully monitored for the appearance of diabetes,” Dr. Clemmons advised. “The dose of growth hormone used should also be kept below 1.0 mg/day.”

“GH therapy is safe and very unlikely to precipitate the development of new onset diabetes as long as one adheres to the rules mentioned above,” Dr. Clemmons said.

He added that “transient increases in fasting glucose can occur in these patients but they often (not always) revert to normal. Therefore an increase in fasting glucose into the diabetic range does not necessarily mean the drug must be stopped. It would be more prudent to reduce the dose, then monitor the patient to determine if the glucose levels improve, in which case the drug can be continued.”

Dr. Clemmons and most of the researchers have received consulting fees and travel expenses from Eli Lilly and Co.

J Clin Endocrinol Metab 2011.