INS and glioblastoma: Glioblastoma, similar to many other solid tumors, are able to exploit glucose-dependent metabolism even in the presence of oxygen to promote cell proliferation.24 As intracerebral glucose concentrations increase with rising plasma glucose, a finding that is exaggerated in patients without prior history of hyperglycemia, tumors in patients with high systemic blood glucose may have greater uptake of metabolic substrates and thus proliferation.25–27 A second possibility is that hyperglycemia influences survival in GBM through increased insulin levels.