Hyperglycemia is the medical term for high blood sugar levels. Glucose, which is a simple sugar (monosaccharide), is essential for energy production and sustaining life. High blood sugar levels damages cells, affects the water and electrolyte balance and disrupts homeostasis.
Causes of Hyperglycemia
Prolonged hyperglycemia is a key feature in diabetes mellitus (sugar diabetes). However, acute episodes may be seen in periods of stress/shock, severe infections, pregnancy, stroke and heart attacks. These non-diabetic causes of hyperglycemia need to be treated in order for the blood sugar levels to return to a normal state. Hyperglycemia in strokes and heart attacks can negatively impact the prognosis. It may also be seen in conditions associated with growth hormone, like gigantism, as growth hormone is one of the accessory hormones (along with cortisol and epinephrine) that can raise blood sugar levels.
The levels of blood glucose is primarily regulated by the pancreatic hormones, insulin and glucagon, as discussed under Normal Blood Glucose. Insulin lowers blood glucose levels by stimulating cells to increase glucose uptake from the blood and triggers the liver to store any excess glucose. Glucagon raises the blood glucose levels when it drops lower than normal. Stored glucose (glycogen) is mobilized and proteins and fats are also used for energy production in a process known as gluconeogenesis.
Raised blood glucose levels may be seen in stressful situations and severe illnesses as discussed above. It is primarily due to the action of the body’s ‘stress hormones’, epinephrine (mainly) and cortisol, which raises the blood glucose levels. Epinephrine reduces the body’s sensitivity to insulin and may also increase gluconeogenesis.
The rise in blood sugar levels is necessary for the body to have greater energy resources available for heightened states (‘fight-flight reponse’). The blood glucose levels return to normal once the stimulus for the stress is removed. Stress hyperglycemia should be monitored closely and reevaluated at regular intervals to exclude the possibility of diabetes mellitus.
Prolonged and persistent elevation in blood glucose levels in diabete mellitus (sugar diabetes) is the consequence of a lack of insulin (type 1 diabetes mellitus) or insulin resistance (type 2 diabetes mellitus). The condition develops gradually and is marked by associated signs and symptoms like polydipsia (constant thirst), polyuria (large volumes of urine in a day ~ frequent urination) and polyphagia (excessive hunger).
Over time, hyperglycemia associated with diabetes mellitus leads to tissue damage. This is most prominent in the nerves and blood vessels and leads to a host of complications. Diabetes mellitus is a chronic condition (irreversible) and proper glucose control (medication, diet and lifestyle) is essential to limit the impact of long standing hyperglycemia.