Urinary excretion of IGF-I and growth hormone in children with IDDM

Short-term suppression of elevated growth hormone concentrations following insulin-like growth factor 1 administration in young adults with type 1 diabetes does not alter glomerular filtration or albumin excretion rates

OBJECTIVE

Young adults with type 1 diabetes mellitus (T1DM) have increased glomerular filtration rate (GFR), which may mediate progressive renal disease and microalbuminuria. This may be secondary to low concentrations of insulin-like growth factor (IGF)-I and GH hypersecretion. We tested the hypothesis that restoration of circulating IGF-I concentrations in young adults with T1DM might suppress GH secretion, GFR and urinary albumin excretion.

DESIGN

In a randomized double blind crossover study six young adults with T1DM (three men, 19-24 years) received 7 days treatment with rhIGF-I/insulin-like growth factor binding protein (IGFBP)-3 complex (SomatoKine) 0.4 mg/kg/day and placebo. Subjects underwent overnight insulin infusion for euglycaemia, followed by determination of GFR and albumin excretion rate.

RESULTS

Following IGF-I/IGFBP-3 complex, overnight insulin requirements (0.15 vs placebo 0.21 mU/kg/min, P < 0.04), plasma insulin (77 vs placebo 152 pmol/l, P < 0.01) and mean overnight GH (2.6 vs placebo 4.8 mU/l, P < 0.04) fell. IGF-I (492 vs placebo 218 ng/ml, P < 0.01) and IGFBP-3 (4.5 vs placebo 3.9 microg/ml, P < 0.05) increased. GFR did not change (145.5 (23.9) ml/min/1.73 m(2) post-IGF-I/IGFBP-3 complex vs 152.2 (19.8) post placebo). Albumin excretion rate did not change 9.5 (5.5-16.6)mg/24 h pre- vs 11.5 (9.9-20.2) post-IGF-I/IGFBP-3 complex and 10.7 (8.1-21.2) pre- vs 11.5 (8.7-29.9) post placebo. Plasma creatinine levels were lower following IGF-I/IGFBP-3 complex (mean +/- SD, 56.2 +/- 16.8 micromol/l) vs placebo (61.5, 45.0, P < 0.02).

CONCLUSIONS

Seven days treatment with IGF-I/IGFBP-3 complex enhanced overnight insulin sensitivity and reduced GH levels, but there was no effect on glomerular hyperfiltration or albumin excretion rates.

Limited joint mobility and lipodystrophy in children and adolescents with insulin-dependent diabetes mellitus

One hundred forty-eight children, aged 11.9 +/- 3.7 years, who had insulin-dependent diabetes mellitus (IDDM) for 4.5 +/- 3.7 years and glycosylated Hb values (HbA1) of 10.5% +/- 4.5%, were examined for limited joint mobility (LJM) and lipodystrophy. In all diabetics, human biosynthetic insulin was used. Six hundred forty-eight pupils, aged 11.8 +/- 2.5 years, served as controls. LJM was found in 28.4% of the diabetics and in 7.5% of the controls (p < 0.001). The presence and severity of LJM was positively correlated with the duration of diabetes and negatively with height. There was no correlation between the presence of LJM and sex, chronological age, age of diabetes onset, HbA1 values, or retinopathy. Lipodystrophy at insulin injection sites was found in 37.1% of the diabetics. Hypertrophic lesions predominated. Our findings and those of the literature lead to the following conclusions: the prevalence of LJM in IDDM subjects of comparable age using Rosenbloom's criteria is almost uniform in all published studies (28%); the correlation, however, of prevalence and severity to different parameters presents discrepancies which cannot be interpreted at present. Human biosynthetic insulin does not protect from lipodystrophy and alterations of insulin injections still remain the only currently available preventive and therapeutic measure.