Belonging to a large gene family of homeodomain-containing transcription factors HOXA5 is part of a regulatory network involved in embryonic development and cellular differentiation as well as in various crucial cell functions and human diseases like diabetes and cancer where deregulated HOXA5 gene expression has been described causally in tumor predisposition and in various stages of tumor progression [54, 55]. This evidence concerns the gene HOXA5 and diabetes mellitus.