In a series of 58 NF1-associated NET cases, about 25% (14 cases) were marked with somatostatin antibodies on immunohistochemistry, but only 28% of the patients presented symptoms related to the hormone secretion, i.e. diabetes mellitus, diarrhea, gallstones, and less frequently dyspepsia and hypochlorhydria (102). This evidence concerns the gene NF1 and diabetes mellitus.