What is diabetic coma?

Diabetic coma is a life-threatening emergency that can affect you if you have diabetes. In a diabetic coma, you are unconscious and unable to respond to your environment. You are either suffering from high blood glucose (hyperglycemia) or low blood glucose (hypoglycemia). You need immediate medical attention if you go into a diabetic coma.

What are the causes of diabetic coma?

Diabetic coma is mainly caused by an extremely high or low blood sugar level. Conditions include:

  • Diabetic hyperosmolar syndrome
    • Blood sugar could be as high as 600 mg/dL
    • No ketones (byproducts of the breakdown of fatty acids) in urine
    • Blood is thicker than normal
    • Happens in people with Type 2 diabetes
  • Diabetic ketoacidosis
    • Could happen with a blood sugar as low as 250 mg/dL or even lower in some cases
    • Body uses fatty acids instead of glucose for fuel
    • Ketones develop in urine and bloodstream
    • More common in people with Type 1 diabetes

What are the symptoms of diabetic coma?

The following symptoms are your body’s warning signs that your blood sugar (glucose) is too high or too low.

Whenever you have these symptoms, check your blood sugar. If it is too high or too low, treat it according to your healthcare provider’s instructions to prevent a diabetic coma. If you have had diabetes for a long time, you may fall into a coma without showing any of the symptoms.

Hyperglycemia (high blood glucose) symptoms are:

  • Tiredness
  • Abdominal pain
  • Shortness of breath
  • Increased urination
  • Weak pulse
  • Drowsiness
  • Walking unsteadily
  • Increased thirst
  • Rapid heart rate
  • Dry mouth
  • Fruity smell to your breath
  • Hunger

Hypoglycemia (low blood glucose) symptoms are:

  • Weakness
  • Sweating
  • Tiredness
  • Anxiety
  • Fast breathing
  • Shakiness
  • Nervousness
  • Nausea
  • Confusion
  • Problems communicating
  • Light-headedness
  • Hunger
  • Dizziness

When blood sugar is too low, the brain does not receive enough fuel. This can be caused by:

  • Drinking too much alcohol
  • Eating too little
  • Exercising too much
  • Taking too much insulin

What are the risk factors of diabetic coma?

While anyone who has diabetes is at risk for a diabetic coma, the causes depend on the type of diabetes:

  • People with Type 1 diabetes have a greater chance of going into a diabetic coma as a result of diabetic ketoacidosis or hypoglycemia. This is because people with Type 1 diabetes always use insulin and have a wider range in their blood glucose levels than people with Type 2 diabetes.
  • People with Type 2 diabetes have a greater chance of going into a diabetic coma from diabetic hyperosmolar syndrome than from diabetic ketoacidosis or hypoglycemia.

Other risks that can lead to diabetic coma in anyone who has diabetes include:

  • Surgery
  • Trauma
  • Illness
  • Insulin delivery problems
  • Poor diabetes management
  • Drinking alcohol
  • Skipping doses of insulin
  • Using illegal substances

Last reviewed by a Cleveland Clinic medical professional on 10/04/2017.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy