Albumin excretion rate, serum insulin-like growth factor-I and glomerular filtration rate in type I diabetes mellitus at puberty.

The albumin excretion rate (AER), insulin-like growth factor-I (IGF-I) levels, glomerular filtration rate (GFR) and glycosylated hemoglobin (HbA1c) levels were studied in 49 diabetic children and 49 controls. The duration of diabetes varied from newly diagnosed to 17.5 years. Diabetics exhibited a wide range of AER values and had significantly higher AER and IGF-I levels compared to controls. At puberty elevated circulating growth hormone (GH) concentrations were found with a parallel increase in the levels of IGF-I. High IGF-I levels were found in 10-12 year-old girls and 15-16 year-old boys in both diabetic and control groups. Positive correlations were found between IGF-I and GFR in girls of both groups (p < 0.05) and in control girls between IGF-I, GFR and microalbuminuria (p < 0.05). The diabetic boys also showed microalbuminuria with respect to controls at high HbA1c levels and when their testis volume exceeded 8 ml (p < 0.05). We concluded that the prominent change in GH release at puberty, reflected by IGF-I, is in pulse amplitude, and that this is increased in diabetes but it is not a very important factor when determining the abnormal levels of urinary albumin excretion.