The blood contains four grams of glucose – a mere teaspoon. This small amount of glucose is so important to the function of the nervous system that the body has evolved a complex system to protect it and maintain “glucose homeostasis.” The body protects blood glucose even during exercise when muscles may increase their glucose uptake from the blood by ten-fold. This session describes how a well-orchestrated hormone response preserves the precious four grams of glucose in the blood under different conditions and the challenges faced by people with diabetes.