NORMAL STIMULATED GROWTH-HORMONE SECRETION BUT LOW PERIPHERAL LEVELS OF INSULIN-LIKE GROWTH-FACTOR-I IN PREPUBERTAL CHILDREN WITH INSULIN-DEPENDENT DIABETES-MELLITUS

The hypothalamo-pituitary-insulin-like growth factor I (IGF-I) axis wa s studied in 24 prepubertal children with insulin-dependent diabetes m ellitus (IDDM) and 12 non-diabetic children. There were no significant differences between the diabetic and control subjects in basal concen trations of immunoreactive growth hormone releasing hormone (ir-GHRH), growth hormone (GH) or stimulated GH levels, but after exercise ir-GH RH concentrations were higher in the diabetic children. Peripheral IGF -I levels were significantly lower in the diabetic children, and even lower in those with poor metabolic control. A positive correlation was found between IGF-I levels and circulating free insulin concentration s in the diabetic subjects (r = 0.49, p < 0.05). These observations su ggest that the GH response to physiological stimulation is normal in p repubertal diabetic children. Exercise-induced GH response may not be mediated by GHRH. IGF-I levels were reduced in prepubertal children wi th IDDM and even more so in subjects with poor metabolic control. This may be a consequence of transitory hypoinsulineamia, emphasizing the importance of adequate insulinization to facilitate optimal growth in children and adolescents with IDDM.