Brain Defense of Glycemia in Health and Diabetes

The brain coordinates the homeostatic defense of multiple metabolic variables, including blood glucose levels, in the context of ever-changing external and internal environments. The biologically defended level of glycemia (BDL) is the net result of brain modulation of insulin-dependent mechanisms in cooperation with the islet, and insulinindependent mechanisms through direct innervation and neuroendocrine control of glucose effector tissues. In this article, we highlight evidence from animal and human studies to develop a framework for the brain’s core homeostatic functions—sensory/afferent, integration/processing, and motor/efferent—that contribute to the normal BDL in health and its elevation in diabetes.