A diabetic coma doesn't strike out of the blue. You'll first experience signs and symptoms of high blood sugar or low blood sugar.

High blood sugar
If your blood sugar level is too high, you may experience:

• Increased thirst
• Frequent urination
• Dry mouth
• Nausea
• Vomiting
• Shortness of breath

Low blood sugar
If your blood sugar level is too low, you may feel:

• Shaky or nervous
• Tired
• Sweaty
• Hungry
• Irritable
• Confused

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Prolonged blood sugar extremes — blood sugar that's either too high or too low for too long — may cause various conditions, all of which can lead to a diabetic coma.

• Diabetic ketoacidosis. If your muscle cells become starved for energy, your body may respond by breaking down fat stores. This process forms toxic acids known as ketones. Left untreated, diabetic ketoacidosis can lead to a diabetic coma. Diabetic ketoacidosis is most common in people who have type 1 diabetes, but it can also affect people who have type 2 diabetes or gestational diabetes.
• Diabetic hyperosmolar syndrome. If your blood sugar level tops 600 milligrams per deciliter (mg/dL), or 33 millimoles per liter (mmol/L), the condition is known as diabetic hyperosmolar syndrome. When your blood sugar gets this high, your blood becomes thick and syrupy. The excess sugar passes from your blood into your urine, which triggers a filtering process that draws tremendous amounts of fluid from your body. Left untreated, diabetic hyperosmolar syndrome can cause life-threatening dehydration and loss of consciousness. Diabetic hyperosmolar syndrome is most common in older adults who have type 2 diabetes.
• Hypoglycemia. Your brain needs glucose to function. In severe cases, low blood sugar may cause you to pass out. Hypoglycemia is most common in people who take too much insulin or skip meals or snacks. Exercising too vigorously or drinking too much alcohol can have the same effect. How quickly your blood sugar drops influences the symptoms of hypoglycemia. For example, if it takes a few hours for your blood sugar to drop 50 mg/dL (3 mmol/L), the symptoms may be minimal. If your blood sugar drops the same amount in a few minutes, the symptoms will be more pronounced.

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Anyone who has diabetes is at risk of a diabetic coma. Risk factors for the conditions that may lead to a diabetic coma vary, however.

For example, diabetic ketoacidosis is most common in people who have type 1 diabetes. Diabetic hyperosmolar syndrome is most common in older adults who have type 2 diabetes — especially those who don't monitor their blood sugar or who don't know they have diabetes.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

A diabetic coma is a medical emergency. If you pass out, you'll need someone to request emergency medical help.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

If you experience a diabetic coma, prompt diagnosis is essential. The emergency medical team will do a physical exam and may ask those who are with you about your medical history.

You may need various lab tests as well. The doctor may measure:

• Your blood sugar level
• Your ketone level
• The amount of nitrogen or creatinine (a breakdown product of creatine, an important part of muscle) in your blood
• The proportion of red blood cells and fluid in your blood (hematocrit)
• The amount of potassium in your blood

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Left untreated, a diabetic coma can lead to permanent brain damage. In some cases, an untreated diabetic coma can be fatal.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Emergency treatment for a diabetic coma depends on whether your blood sugar level is too high or too low.

If your blood sugar level is too high, you may be given intravenous fluids to restore water to your tissues. You may need potassium, sodium or chlorine supplements to help your cells function correctly. When enough fluid has been replaced, short-acting insulin may be used to help your tissues absorb glucose again. Any underlying infections will be treated as well.

If your blood sugar level is too low, you may be given an injection of the hormone glucagon. The injection will cause your blood sugar level to quickly rise.

Consciousness typically returns when blood sugar reaches a normal level.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

Good day-to-day control of your diabetes can help you prevent a diabetic coma. Keep these tips in mind:

• Follow your meal plan. Consistent snacks and meals can help you control your blood sugar level.
• Keep an eye on your blood sugar level. Frequent blood sugar tests can tell you whether you're keeping your blood sugar level in your target range — and alert you to dangerous highs or lows.
• Take your medication as directed. If you have frequent episodes of high or low blood sugar, your doctor may adjust the dosage or timing of your medication. Your doctor may recommend regular glycated hemoglobin tests to determine how well you're managing your blood sugar.
• Educate your loved ones, friends and co-workers. Teach loved ones and other close contacts how to recognize early signs and symptoms of blood sugar extremes — and how to summon emergency help should you pass out.
• Wear a medical ID bracelet or necklace. If you're unconscious, the ID can provide valuable information to your loved ones, co-workers and others — including emergency personnel.

Above all, keep your perspective. For most people who have diabetes, the risk of a diabetic coma is small. Take good care of yourself to help prevent diabetes complications.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.