In a previous extensive review of this topic in 2007, De Groot et al. reported that, of the IGF-II-producing tumors causing hypoglycemia, 41% had a mesenchymal origin, 43% had an epithelial origin, 1% had a neuroendocrine and hematopoietic origin, and 14% had an unknown origin [6]. This evidence concerns the gene IGF2 and Hypoglycemia.