In the T1DBIT and DIABIMMUNE studies, lower IGF-1 levels were reported in children with islet autoimmunity and type 1 diabetes than in autoantibody-negative children (27, 28), which may be caused by decreased intraportal insulin levels leading to growth hormone resistance in the liver and thereby to lower IGF-1 production (29). This evidence concerns the gene GH1 and type 1 diabetes mellitus.