Cortisol, a steroid hormone, more specifically a glucocorticoid, is produced by the the adrenal gland, a small gland that sits on the top of the kidney. Cortisol is released in response to stress and a low level of blood glucose. Its primary functions are to increase blood sugar synthesis by using protein and fat sources. Prolonged exposure to cortisol, in the same fashion as prolonged exposure to any other kind of steroid, alters the normal glucose metabolism. Cortisol counteracts insulin (the hormone that is released by the pancreas upon increase in blood sugar after meals to increase sugar uptake into cells), and this contributes to hyperglycemia (high blood sugar) and blocks the utilization of glucose by tissues, resulting in insulin resistance.