In a randomized, double-blind, placebo-controlled clinical trial in 166 adult patients with GHD, treatment with GH was associated with a worsening of glucose tolerance with the appearance of diabetes in 4% and carbohydrate intolerance in 20% of patients after 12 months, while in the placebo group only 8% developed intolerance [32]. This evidence concerns the gene GH1 and diabetes mellitus.