This may be due to a number of factors: the disease process itself; other patient factors that impact GH levels, such as malnutrition, diabetes mellitus, thyroid disorders, kidney or liver failure, or adolescence; or, importantly, inappropriate cut-offs for GH levels in the dynamic function tests and/or IGF-1 assays used, or the performance characteristics of the assays [6,7,12,13,14]. Here, GH1 is linked to diabetes mellitus.