Growth hormone and IGF-I in diabetic children with and without microalbuminuria.

In order to evaluate the relationship between urinary GH, urinary IGF-I and plasma IGF-I levels and presence of incipient diabetic nephropathy in paediatric age, we studied fifty (25 male and 25 female) prepubertal patients with insulin-dependent diabetes mellitus (T1DM). The patients were subdivided into two groups according to the presence of persistent microalbuminuria defined as albumin excretion rate (AER) >20 microg/min in at least 5 urine collections in the 6 months prior to the beginning of the study: Group A: 18 patients with microalbuminuria; Group B: 32 patients without microalbuminuria. A group of 20 healthy subjects, sex-, age- and pubertal stage-matched, served as control. No difference was observed between the urinary output of IGF-I and GH and plasma IGF-I values between normoalbuminuric and control subjects (normoalbuminuric vs controls: urinary GH: mean+/-SD 7.9+/-0.7 ng/day vs 8.1+/-0.6; urinary IGF-I: 178.3+/-19.7 ng/day vs 175.5+/-20.3; plasma IGF-I: 203.9+/-31.2 ng/ml vs 199.4+/-43.2), but a significant difference was observed between the urinary output of IGF-I and GH and plasma IGF-I levels between microalbuminuric patients and normoalbuminuric and controls (microalbuminuric subjects: urinary GH: 13.1+/-1.4 p<0.01; urinary IGF-I: 451.3+/-45.9 p<0.001; plasma IGF-I: 326.5+/-63.2 p<0.01). Moreover, plasma IGF-I, urinary GH and urinary IGF-I were not significantly associated with microalbuminuria, while plasma IGF-I levels were positively related to glomerular filtration rate (GFR) (p<0.05). In conclusion, our study demonstrates that microalbuminuric patients have higher levels of urinary IGF-I, urinary GH, plasma IGF-I than normoalbuminuric diabetic subjects. These data support the hypothesis that IGF-I can have a role in the changes of renal function observed in patients with persistent microalbuminuria.