title: Impaired insulin action in the human brain: causes and metabolic consequences.
abstract: Over the past few years, evidence has accumulated that the human brain is an insulin-sensitive organ. Insulin regulates activity in a limited number of specific brain areas that are important for memory, reward, eating behaviour and the regulation of whole-body metabolism. Accordingly, insulin in the brain modulates cognition, food intake and body weight as well as whole-body glucose, energy and lipid metabolism. However, brain imaging studies have revealed that not everybody responds equally to insulin and that a substantial number of people are brain insulin resistant. In this Review, we provide an overview of the effects of insulin in the brain in humans and the relevance of the effects for physiology. We present emerging evidence for insulin resistance of the human brain. Factors associated with brain insulin resistance such as obesity and increasing age, as well as possible pathogenic factors such as visceral fat, saturated fatty acids, alterations at the blood-brain barrier and certain genetic polymorphisms, are reviewed. In particular, the metabolic consequences of brain insulin resistance are discussed and possible future approaches to overcome brain insulin resistance and thereby prevent or treat obesity and type 2 diabetes mellitus are outlined.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University, Partners in the German Centre for Diabetes Research (DZD), Otfried-Müller-Street 10, 72076 Tübingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Heni
authors.affiliation: Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Partners in the German Centre for Diabetes Research (DZD), Otfried-Müller-Street 10, 72076 Tübingen, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kullmann
authors.affiliation: Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen, Partners in the German Centre for Diabetes Research (DZD), Otfried-Müller-Street 10, 72076 Tübingen, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Preissl
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University, Partners in the German Centre for Diabetes Research (DZD), Otfried-Müller-Street 10, 72076 Tübingen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fritsche
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University, Partners in the German Centre for Diabetes Research (DZD), Otfried-Müller-Street 10, 72076 Tübingen, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Häring
mesh_terms: D001835:Body Weight / Q000502:physiology; D001923:Brain Chemistry; D003071:Cognition; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D005247:Feeding Behavior; D006801:Humans; D007328:Insulin / Q000378:metabolism* / Q000502:physiology; D007333:Insulin Resistance
chemical_list: D007328:Insulin