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High Blood Sugar
(Hyperglycemia)

High Blood Sugar (Hyperglycemia) Facts

Whenever the glucose (sugar) level in one's blood rises high temporarily, this condition is known as hyperglycemia. The opposite condition, low blood sugar, is called hypoglycemia.

Glucose comes from most foods, and the body uses other chemicals to create glucose in the liver and muscles. The blood carries glucose (blood sugar) to all the cells in the body. To carry glucose into the cells as an energy supply, cells need help from insulin. Insulin is a hormone made by the pancreas, an organ near the stomach.

The pancreas releases insulin into the blood, based upon the blood sugar level. Insulin helps move glucose from digested food into cells. Sometimes, the body stops making insulin (as in type 1 diabetes), or the insulin does not work properly (as in type 2 diabetes). In diabetic patients, glucose does not enter the cells sufficiently, thus staying in the blood and creating high blood sugar levels.

Blood sugar levels can be measured in seconds by using a blood glucose meter, also known as a glucometer. A tiny drop of blood from the finger or forearm is placed on a test strip and inserted into the glucometer. The blood sugar (or glucose) level is displayed digitally within seconds.

Blood glucose levels vary widely throughout the day and night in people with diabetes. Ideally, blood glucose levels range from 90 to 130 mg/dL before meals, and below 180 mg/dL within 1 to 2 hours after a meal. Adolescents and adults with diabetes strive to keep their blood sugar levels within a controlled range, usually 80-150 mg/dL before meals. Doctors and diabetes health educators guide each patient to determine their optimal range of blood glucose control.

When blood sugar levels remain high for several hours, dehydration and more serious complications can develop. Moreover, even mild hyperglycemia (a fasting blood sugar over 109 mg/dL in adolescents/adults or over 100 mg/dL in children before puberty) - when unrecognized or inadequately treated for several years - can damage multiple tissues in the brain, kidneys, and arteries. When hyperglycemia is associated with the presence of ketones in the urine, this state demands immediate medical attention. When blood sugar levels rise and stay high (over 165 mg/dL consistently) for days to weeks, diabetes should be suspected and treatment initiated.

High blood sugar level fluctations occur daily in people with diabetes. It is important to control blood sugar levels through diet, exercise, and medication (if prescribed), to know the symptoms of elevated blood sugar, and to seek treatment, when necessary.

High Blood Sugar Causes

Diabetes mellitus is one of several persistent conditions causing high blood sugar levels. For someone with diabetes, hyperglycemia has many possible causes:

  • Carbohydrates: Eating food containing too many carbohydrates, a form of sugar. The body of a person with diabetes cannot process high levels of carbohydrates fast enough to convert it into energy. Blood sugar levels in patients with diabetes can rise within hours after eating.
  • Insulin control: Not producing enough insulin action (either by injection of insulin or taking medicine which stimulates the pancreas to make more insulin). People with diabetes must control blood sugar by a combination of dietary discretion, taking medication, and physical activity. When food, exercise, and insulin are not balanced, blood sugar levels rise.
  • Stress: Emotions can play a role in causing hyperglycemia, but should not be used as an excuse for poor control of diabetes.
  • Low levels of exercise: Daily exercise is a critical contributor to regulating blood sugar levels.
  • Infection, illness, or surgery: With illness, blood sugar levels tend to rise quickly over several hours.
  • Other medications: Certain drugs, especially steroids, can affect blood sugar levels.
Medically Reviewed by a Doctor on 3/2/2016

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