Insulin sensitivity in growth hormone-deficient children: influence of replacement treatment

OBJECTIVE: In adults, excessive GH secretion may lead to secondary diabetes mellitus, while prolonged GH treatment may accelerate the onset of type 2 diabetes mellitus in predisposed children. The aim of the study was to evaluate insulin sensitivity (IS) and glucose tolerance (GT) in a group of GH-deficient children treated with GH for a period of 6 years. PATIENTS AND DESIGN: One hundred and twenty-eight children (40 females, 88 males) were included in the study. At the beginning of treatment chronological age was 8.9 +/- 3.2 years, height standard deviation score (SDS) -2.43 +/- 0.90 and body mass index (BMI) SDS 0.18 +/- 1.60. At the end of the study chronological age was 13.0 +/- 2.9 years, height SDS -1.24 +/- 1.27 and BMI SDS 0.23 +/- 1.54. GH was administered at a mean weekly dosage of 0.3 mg/kg, injected subcutaneously over 6-7 days. GT was assessed according to the criteria of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. IS was evaluated with the quantitative insulin sensitivity check index (QUICKI). RESULTS: No cases of impaired GT or diabetes were recorded during the follow-up period. IS, already lower than in controls before starting treatment with GH, decreased significantly during the first year of therapy (QUICKI: 0.346 +/- 0.033 vs. 0.355 +/- 0.044, P < 0.05), with no further decrease in the following years. No correlation was found between QUICKI, BMI, years of treatment and onset of puberty. CONCLUSIONS: GH treatment in GH-deficient children does not lead to an impaired GT or type 2 diabetes mellitus, although it does significantly decrease IS.