Hyperglycemia is defined as a blood glucose over 130 mg per deciliter, according to the American Diabetes Association. Diabetes is the most common cause, and a hemoglobin A1C of greater than 6.5 percent on two tests, done three months apart, can diagnose this disease, according to the Mayo Clinic's Department of Endocrinology. But there are many other causes of high blood glucose as well.
Diabetes
In Type 2 diabetes, blood glucose is elevated because insulin, the hormone from the pancreas that drives glucose into cells, is unable to pass through cell membranes or attach to glucose well enough to serve in this role. According to the American Diabetes Association, 90 percent of people with diabetes have this form of the disease, which can go undiagnosed for many years.
In Type 1 diabetes, the pancreas stops making insulin and blood glucose rises rapidly.
Diabetics can experience hyperglycemia when they have an infection, surgery, trauma, a heart attack or stroke, or when they are on corticosteroids, diuretics, birth control pills or hormone replacement in menopause. Blood glucose can also elevate when too many calories are consumed, too many carbohydrates are eaten in the diet or exercise is decreased.
Acute Stress Hyperglycemia
Acute stress can take many forms and it can cause hyperglycemia in even nondiabetic patients. Trauma, burns, myocardial infarction or heart attack, and cerebral vascular accidents or stroke are all possible causes, according to the American Association for Clinical Chemistry.
A prolonged seizure can also causes a sudden and dramatic elevation in blood glucose. When the seizure ends, this level falls just as rapidly, causing swelling of the brain.
Pancreatic Causes of Hyperglycemia
Both pancretic cancer and pancreatitis are causes of hyperglycemia because the pancreas stops producing an adequate supply of insulin when damaged. The hyperglycemia of pancreatitis is usually reversible once the inflamation resolves.
Medications that Cause Hyperglycemia
Medications can cause hyperglycemia by raising the amount of circulating glucose. Diuretics, medications designed to increase urine output, raise the concentration of glucose in the blood by removing the water that normally dilutes glucose.
Corticosteroids, tricyclic antidepressants, antipsychotic agents, birth control pills and hormone replacement therapy raise the glucose level by causing gluconeogenesis, the process of making free glucose from fatty acids and amnio acids.
Epinephrine and dilantin cause the body to mobilize more stored glucose in the liver, and lithium, a medication used to treat bipolar disorder, can cause thyroid disorders that lead to hypergylcemia.
Hyperglycemia from illnesses
Infections, especially septicemic or blood-born infections and those that cause tissue death or necrosis, are capable of causing hyperglycemia. So can infections that cause dehydration, including influenza and any cause of vomitting and diarrhea.
Cushing's syndrome, caused by having too much cortisol in the body, can be caused by taking steroids in excessive quantity or for a prolonged period of time. It can also occur when the adrenal gland begins to make too much of this hormone. Regardless of the cause, Cushing's syndrome leads to hyperglycemia.
