Acute activation of the stress response mobilizes energy to meet immediate demands, and in non-diabetics this produces predictable changes in glucose handling. Acute stress triggers the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, releasing epinephrine and cortisol that together increase hepatic glucose output and transiently reduce peripheral glucose uptake. Robert M. Sapolsky at Stanford University explains how these hormones shift metabolism toward rapid fuel availability, while George P. Chrousos at the National Institutes of Health outlines the HPA axis role in coordinating that endocrine response. The overall effect is a short-lived rise in blood glucose that supports fight-or-flight activities.
Mechanisms
Epinephrine from the adrenal medulla stimulates glycogenolysis and gluconeogenesis in the liver and inhibits insulin secretion and insulin-stimulated glucose uptake in skeletal muscle, producing a quick increase in circulating glucose. Cortisol amplifies this by promoting gluconeogenic enzymes and by inducing transient insulin resistance in peripheral tissues, preserving glucose for high-priority organs such as the brain. These physiological processes are adaptive in the short term, enabling rapid cognitive and physical responses. Bruce S. McEwen at The Rockefeller University framed repeated activation of these pathways as accumulating physiological wear and tear, a concept termed allostatic load that links repeated acute stressors to longer-term metabolic consequences.
Relevance and consequences
In otherwise healthy people the hyperglycemic effect of a single acute stressor is usually short-lived because pancreatic beta cells respond by increasing insulin secretion and tissues restore normal uptake once catecholamine levels fall. Context matters: the magnitude and duration of glucose changes depend on stressor intensity, prior conditioning, sleep, nutrition, and concurrent illness. Recurrent or prolonged acute stress episodes, especially when combined with poor sleep or limited access to nutritious food in certain social or territorial settings, can contribute to sustained alterations in glucose regulation and elevate cardiometabolic risk over time. Clinically, understanding these dynamics helps interpret transient glucose elevations during medical procedures or traumatic events and informs strategies for workplace health in high-stress occupations such as emergency response. Recognizing the hormonal drivers and the social-environmental modifiers supports targeted interventions to reduce harmful metabolic sequelae while preserving the adaptive benefits of the acute stress response.