Effect of Puberty on Insulinlike Growth Factor I and HbA1 in Type I Diabetes

Abstract

Objective To assess the effect of puberty on the relationship between glycemic control and insulinlike growth factor I (IGF-I) levels in children with insulin-dependent (type I) diabetes mellitus. Research Design and Methods Simultaneous HbA1 and plasma IGF-I levels were determined in 71 prepubertal (Tanner stage I) and 112 pubertal (Tanner stages II-V) subjects aged 2.7–17.8 yr. Results Overall, IGF-I levels were positively correlated with both age (r = 0.31, P < 0.001) and Tanner stage (r = 0.32, P < 0.001) but only weakly associated with HbA1 values (r = −0.16, P = 0.025). A strong negative association existed between IGF-I and HbA1 levels (r = −0.45, P < 0.001) in the pubertal subjects, but no such association was apparent in the prepubertal subjects. Multiple regression analyses disclosed a significant independent negative association between IGF-I and HbA1 levels in the pubertal group (P < 0.001) but not in the prepubertal group. Conclusions Glycemic control appears to strongly influence IGF-I levels only after the onset of puberty.