Insulin Sensitivity Decreases in Short Children Born Small for Gestational Age Treated with Growth Hormone

Objectives

To evaluate insulin sensitivity in short children born small for gestational age (SGA) treated with growth hormone (GH), and to study the relationship between growth response and insulin levels.

Study design

In 29 children (16 female, 13 male) who were short and SGA, an oral glucose tolerance test was performed before (mean age, 8.8 years; range, 4.5-14.3 years) and after 1 year of GH treatment (33 μg/kg/day). Insulin sensitivity was calculated with the homeostasis model assessment (HOMA) and the insulin sensitivity index (ISI) of Matsuda.

Results

The mean height increased from −3.1 to −2.4 SD. Insulin resistance (ISI <5) was seen in 17.2% of children before and in 48.3% (mainly pubertal) children after GH treatment. Insulin sensitivity decreased significantly: ISI fell from 12.2 to 6.1 (P = .02) and HOMA increased from 1.2 to 2.2 (P = .001). Glucose and HbA1c levels did not change significantly. ISI after 1 year did not correlate with height gain, but it did correlate with age (r = −0.469; P = .01) and body mass index (r = −0.52; P = .004).

Conclusions

Insulin sensitivity is impaired in some children who are SGA already at baseline and decreases with GH treatment in most of them. Children close to puberty and children who are less underweight have the highest risk to become insulin resistant.

Abbreviations: AUC, Area under the curve, BMI, Body mass index, GH, Growth hormone, HOMA, Homeostasis model assessment, ISI, Insulin sensitivity index, OGTT, Oral glucose tolerance test, SGA, Small for gestational age