Photo;By Danny Hope from Brighton & Hove, UK (My Right Eye Uploaded by Pieter Kuiper) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons Thus the twin toxic hypers of modern excess sugar consumption, hyperglycaemia and hyperinsulinism, separately and synergistically suppress and inhibit glucose transport into the brain via suppression of the cerebral glucose pump – the glutamate/glutamine cycle, known as the iPump. Neither fats nor proteins play any part in this pathological process – indeed fats play a positive role in cerebral glucose metabolism via leptin, adiponectin and fibroblast growth factor 9 (FGF 9). 34 The Hungry Retina and Dementia The human retina consumes even greater energy on a cell for cell basis than does the human brain, which is why it is the most vulnerable tissue in any decrement in energy supply. We know this from any attack of hypoglycaemia; the retina cells are the first cerebral energy cells to respond – vision is blurred and stars appear in the visual field. Modern humans are subject not to chronic energy deficits but to chronic energy overload in the circulation, and here again we observe that the first tissue to register the suppression of the retinal glucose pump are the retinal glial cells; glutamate, the cerebral (retinal) hunger signal, is not converted to glutamine, and glutamate is the most excitotoxic amino acid in the brain; excess accumulation of toxic glutamate and damage to the retina is expressed many years before visual loss manifests.