Insulin-like growth factor I, its binding proteins 1 and 3, and growth hormone-binding protein in children and adolescents with insulin-dependent diabetes mellitus: clinical implications

Abstract

Values of IGF-I after extraction, its binding proteins, and the high affinity GH-binding protein (BP) are not well established in pediatric patients with insulin-dependent diabetes mellitus (IDDM). We report data for IGF-I, IGFBP-1, and -3, and GHBP in 92 Spanish children with IDDM, separated according to pubertal stage: prepubertal (n = 49); pubertal onset (n = 17); mid-puberty (n = 17), and complete puberty (n = 9), as well as to metabolic control (HbA1 < 9% or > or = 9%). IGF-I levels in IDDM patients increased throughout development (p < 0.001), but were diminished at every developmental stage when compared with marched control subjects. IGF-I concentrations showed a negative correlation with the degree of metabolic control, in particular during the prepubertal stage of development. A negative correlation (r = -0.22; p < 0.005) between IGF-I concentrations and HbA1 was found. Serum IGFBP-I levels diminish during maturation in diabetic patients (p < 0.001). However, IDDM patients have significantly higher levels of IGFBP-1 than control subjects at every stage of development, and IDDM patients with inadequate metabolic control exhibit even greater differences when compared with matched control subjects. A positive correlation (r = 0.22; p < 0.005) between IGFBP-1 concentrations and HbA1 was found. IGFBP-3 serum levels were similar to those observed in normal subjects, and no correlation was observed in relation to the metabolic control. In IDDM patients, GHBP levels change significantly during maturation, as they do in normal control subjects; however, significantly lower GHBP levels were found in prepubertal and pubertal IDDM patients. GHBP levels were independent of metabolic control, although a tendency toward lower levels of GHBP was seen when HbA1 levels increased. We suggest that a partial GH resistance syndrome exists in IDDM patients, and this may be related to the metabolic control. Hence, the biochemical markers measured here may be of value in evaluating the smaller pubertal growth spurt in diabetic patients.