In this post hoc secondary analysis of a randomized clinical trial of 398 participants with youth-onset T2D, changes from baseline to 3 years in plasma concentrations of growth hormone mediators, including insulin-like growth factor-1, growth hormone receptor, and insulin-like growth factor binding protein 1, were associated with glycemic failure and measures of insulin resistance and beta cell function. Here, GH1 is linked to type 2 diabetes mellitus.