HYPERGLYCEMIA

elevation of glucose levels in the blood beyond the normal range; it is the chief diagnostic laboratory symptom of diabetes mellitus (q.v.). Hyperglycemia results from a breakdown in the body's regulation of its metabolism of carbohydrates, and the condition is specifically due to a relative deficiency of the hormone insulin. Since insulin is important in the mechanism that removes glucose from the bloodstream and increases the storage of sugar in the liver, the relative lack of this hormone allows glucose circulating in the blood to accumulate. Sustained hyperglycemia in persons with diabetes causes the typical clinical symptoms of thirst and blurred vision in such patients. Excessive circulating glucose is directly toxic to the nervous system and causes numbness and tingling.