What role does Cortisol play in blood sugar?

Cortisol is a glucocorticoid hormone released by the adrenal cortex in response to stress. Its primary role in blood sugar regulation is to increase glucose availability. It does this by stimulating gluconeogenesis in the liver (production of glucose from amino acids and glycerol) and by reducing peripheral glucose uptake (insulin antagonism). Chronically elevated cortisol, as in Cushing's syndrome or chronic stress, leads to hyperglycemia and can contribute to insulin resistance and type 2 diabetes. Conversely, cortisol deficiency (Addison's disease) can cause hypoglycemia. While consumer DNA tests may report variants in genes related to cortisol metabolism (e.g., NR3C1, HSD11B1), the clinical utility of such testing for blood sugar management is limited. Standard clinical assessment (cortisol levels, glucose tolerance) is more reliable. Evidence: human-strong (well-established physiology).