The brain is crucial for the regulation of whole-body metabolism and behavior. The pancreas-derived hormone insulin modulates brain function and affects energy metabolism as well as cognition. This is partially achieved by modulating several types of brain cell populations including those relevant to satiety and reward. Importantly, brains of Alzheimer´s disease patients exhibit a signature of brain insulin resistance with perturbed brain metabolism. This book will cover the basics of insulin signaling in the brain and will describe concepts of insulin resistance, a feature of type 2 diabetes. Moreover insulin´s effect on cognitive function will be pointed out and the association between brain insulin resistance and neurodegenerative diseases discussed. Additionally, potential behavioral and pharmacological concepts which can affect brain insulin signaling will be summarized.