Cerebral insulin signaling seems to be likewise affected in schizophrenia [27, 28], probably causing disturbances in neural glucose uptake and utilization, as revealed by measurements of elevated CSF glucose levels [29], in vivo fluorodeoxyglucose positron emission tomography (FDG-PET) and functional magnetic resonance imaging (fMRI) studies [30–32]. This evidence concerns the gene INS and schizophrenia.