THE SERUM GROWTH HORMONE-BINDING PROTEIN IS REDUCED IN YOUNG-PATIENTS WITH INSULIN-DEPENDENT DIABETES-MELLITUS

Despite elevated serum concentrations of GH, longitudinal growth is stunted in a considerable number of children and adolescents with insulin-dependent diabetes mellitus (IDDM). To elucidate, whether reduced peripheral action of GH contributes to this phenomenon, GH-binding protein (GH-BP) activity was measured in 117 children and adolescents with IDDM (mean age 14.6 yr, range 4.5-28 yr) and 132 healthy controls (13.1 yr, 6.3-26 yr). Serum was incubated with I-125-GH, then chromatographed on a Sephacryl S200 column (1.8.100 cm), apparent binding of I-125-GH to GH-BP was corrected for the amount of endogenous GH present in the sample. GH-BP activity was significantly lower in IDDM patients, with a corrected binding of 16.8 +/- 0.6% compared to 21.3 +/- 0.7% in control children (mean +/- SE; P < 0.0001, Wilcoxon-test). Previous studies demonstrated that GH-BP is increased in healthy overweight children. In contrast, in IDDM children, GH-BP was reduced despite a moderate degree of overweight (z-score for weight: +0.94 +/- 0.12; mean +/- SE). Reduced serum GH-BP activity in IDDM children is further accentuated when compared to healthy children with a similar degree of overweight (22.8 +/- 0.5%; n = 44). Based on this novel finding, we conclude that decreased GH receptor density may explain reduced growth velocity despite increased secretion of GH in some IDDM children.