High Blood Sugar (Hyperglycemia)

What is hyperglycemia?

Hyperglycemia is a high level of sugar in the blood. Blood sugar is also called glucose.

How does it occur?

Hyperglycemia can occur in healthy people for a brief time after they eat foods very high in sugar, for example, after drinking a large milkshake or eating a large dessert. This may result in a brief high blood sugar level, but the body will process the sugar and the level of sugar in the blood will soon return to normal.

Hyperglycemia is the main problem if you have diabetes. If you have the form of diabetes called type 1 diabetes, hyperglycemia occurs because you do not have enough insulin to move sugar from the blood into all your cells. (Insulin is made by the pancreas.) In type 2 diabetes, high blood sugar usually occurs because the cells have become unable to use insulin. In both cases the sugar cannot move from the blood into the cells, so high levels of sugar build up in the blood.

Hyperglycemia may occur if you are not diabetic but have another illness that makes it hard for your body to process sugar, such as an inflammation of the pancreas (called pancreatitis). This can also happen with some medicines, especially steroids. These conditions are usually temporary and your blood sugar usually becomes normal after you are no longer ill or your medicine can be stopped.

What are the symptoms?

Usually hyperglycemia causes no symptoms, especially if it's brief. However, if the blood sugar rises to 300 milligrams per deciliter (16.7 millimoles per liter) or higher and stays that high for a day or longer, symptoms may occur. Symptoms may include:

• blurry vision
• dry mouth
• feeling unusually thirsty and feeling the need to drink large amounts of liquids
• increased urination
• tiredness.

Severe hyperglycemia--that is, blood sugars of 600 mg/dL (33.3 mmol/L) or higher--can cause coma and even death.

How is it diagnosed?

The level of sugar in your blood can be measured with a blood test. The test should be done before breakfast, after several hours of no food or drink except water. This is called a fasting blood sugar test.

• A normal fasting blood sugar is 70 to 99 mg/dL (3.9 to 5.5 mmol/L).
• 100 to 125 mg/dL (5.5 to 6.9 mmol/L) is mildly abnormal and is called a prediabetic blood sugar level.
• A fasting blood sugar level of 126 mg/dL (7.0 mmol/L) or higher indicates diabetes.

The blood test should be repeated to confirm the diagnosis.

How is it treated?

The treatment depends on whether you have type 1 or type 2 diabetes.

Type 2 diabetes can be treated with:

• diet
• exercise
• medicine if diet and exercise are not enough to lower the blood sugar.

Type 1 diabetes occurs when the body (pancreas) stops making insulin. Therefore the only treatment is insulin.

Severe hyperglycemia is a medical emergency and must be treated right away, starting with IV (intravenous) fluids and insulin. You may need to stay several days at the hospital to get the blood sugar back to normal, to treat any problems caused by the high blood sugar, and to see if the cause of the high blood sugar is an infection or other illness.

Severe hyperglycemia usually occurs:

• in people who have not yet been diagnosed with type 1 diabetes
• in poorly controlled diabetes, types 1 or 2
• when a second medical problem, such as an infection, occurs with type 1 or 2 diabetes

How long will the effects last?

How long hyperglycemia lasts depends on why it occurred and how well you follow the directions for controlling it.

• Type 1 diabetes is a lifelong condition. Its symptoms increase or decrease depending on your response to the insulin and your diet and on how well you are able to control your blood sugar level.
• If you have type 2 diabetes, you will need to be careful about your diet, get enough exercise, and possibly take medicine to keep your blood sugar normal for the rest of your life.

If you have diabetes and do not have proper treatment for it, you may develop a very dangerous complication called ketoacidosis. When your body cannot move sugar into your cells, the cells break down fat for energy. The fat byproducts (ketones) and high sugar level can cause ketoacidosis, which is a life-threatening chemical imbalance and needs emergency treatment at the hospital.

Hyperglycemia that occurs from medicines that you are taking usually goes away when the medicine is stopped.

How can I take care of myself?

You should make sure you understand why your blood sugar is high. You should follow your healthcare provider's directions carefully to keep your blood sugar normal. This usually means you need to:

• Eat a healthy diet as recommended by your healthcare provider.
• Exercise according to your provider's recommendation most days of the week.
• Take medicine exactly as directed, if any has been prescribed.
• Check your blood sugar as often as your provider recommends.

Not keeping your blood sugar at normal levels can cause very serious problems, including heart and blood vessel disease, strokes, kidney failure, and loss of vision.

What can I do to prevent hyperglycemia?

If you are not diabetic and there are others in your family who have hyperglycemia or type 2 diabetes, you should:

• Have your blood sugar checked at least once a year.
• Keep a healthy weight for your height and age.
• Exercise regularly according to your healthcare provider's recommendation.

If you have fasting blood sugar levels in the prediabetes range--that is, 100 to 125 mg/dL--your level of blood sugar can become normal with a healthy diet and regular exercise, thus avoiding type 2 diabetes. But the potential for developing type 2 diabetes is always there.

If you do have diabetes, follow your healthcare provider's recommendations for:

• eating healthy
• getting physical activity
• taking your medicines to keep your blood sugar normal
• keeping your checkup appointments.