Because of the importance of receptors activation and potential effects on the IGF system, a head-to-head comparison of the eventual differential impact of intermediate-acting human insulin (NPH), insulin detemir and insulin glargine on the growth hormone—insulin-like growth factor—insulin-like growth factor binding protein (GH-IGF-IGFBP) axis is relevant to be conducted for the safety assurance of insulin analogues. Therefore, this study aims to investigate whether the serum insulin profile obtained by once-daily injection of long-acting insulin analog, insulin detemir or insulin glargine, has a different impact on IGFBPs production and IGF-I concentrations (total IGF-I) bioactivity and tissue-availability as compared to that seen during treatment with intermediate-acting human insulin, NPH insulin.