Diabetes-Related Coma

A diabetes-related coma is a life-threatening emergency that can happen from having very high or very low blood sugar. Anyone who is unresponsive or in a coma needs immediate medical care. Call 911 or your local emergency services number if you’re near someone in a diabetes-related coma.


What is a diabetes-related coma?

A diabetes-related coma is a life-threatening complication that can result from very high blood sugar (hyperglycemia) or very low blood sugar (hypoglycemia). A coma is a prolonged, deep state of unconsciousness. People in comas are unresponsive but still alive.

Three diabetes complications can lead to a coma, including:

A person in a diabetes-related coma needs immediate medical attention. Call 911 or your local emergency number.

Hyperosmolar hyperglycemic state

Hyperosmolar hyperglycemic state (HHS) is a life-threatening complication of diabetes — mainly Type 2 diabetes. HHS happens when your blood glucose (sugar) levels are too high for a long period, leading to severe dehydration and confusion. Blood sugar levels are usually over 600 milligrams per deciliter (mg/dL).

If you don’t get treatment for HHS in time, it can lead to a coma.

Diabetes-related ketoacidosis

Diabetes-related ketoacidosis (DKA) is a life-threatening complication that mainly affects people with diagnosed or undiagnosed Type 1 diabetes. But it sometimes affects people with Type 2 diabetes as well.

DKA happens when your body doesn’t have enough insulin (natural or synthetic). Your body needs insulin to make glucose in your blood enter your cells, where it’s used as fuel for energy. If there’s no insulin or not enough insulin, your body starts breaking down body fat for energy instead. As your body breaks down fat, it releases ketones into your bloodstream.

For a person with diabetes, a high amount of ketones causes their blood to become acidic. If you don’t get treatment for DKA in time, it can lead to a coma.

Someone who has DKA usually has blood sugar levels above 250 mg/dL. But the main causes of DKA are a lack of insulin and ketones, not just high blood sugar. People with diabetes can have blood sugar over 250 mg/dL and not have DKA.

Severe low blood sugar (hypoglycemia)

Severe hypoglycemia happens when your blood sugar is below 40 mg/dL. This is life-threatening.

Glucose is the main source of energy for your body and brain. When your blood glucose is low, your body can’t function properly. If your blood sugar drops really low (like below 40 mg/dL), you likely won’t be able to function because of the physical and mental changes that occur. Prolonged severe hypoglycemia that’s not treated in time can lead to a coma.

Most cases of severe hypoglycemia affect people with diabetes who take insulin or certain oral diabetes medications, like sulfonylureas.


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Symptoms and Causes

What are the symptoms of a diabetes-related coma?

The three main symptoms of a coma include:

  • Unconsciousness: This is like a very deep sleep, and it’s impossible to wake you up.
  • Lack of eye response: This means your eyes stay closed, and someone holding your eye open doesn’t cause you to react. Your eyes might have some reflex responses, such as reacting to light.
  • Lack of motor (movement) response: This means you don’t consciously move. You may still have some reflex responses.

Severe symptoms of DKA that could happen before a diabetes-related coma include:

Symptoms of HHS that could happen before a diabetes-related coma include:

Symptoms of severe low blood sugar that could happen before a diabetes-related coma include:

  • Blurred or double vision.
  • Slurred speech.
  • Clumsiness or difficulty with coordination.
  • Being disoriented.
  • Seizures.

First aid for diabetes-related comas

If someone near you goes into a diabetes-related coma, follow these first-aid steps:

  • Immediately call 911 or your local emergency services number for an ambulance. If you know the person in a coma has diabetes, let the 911 operator know.
  • Don’t give them anything to eat or drink. They could choke.
  • Turn them onto their side so nothing can block their breathing (like spit or vomit).
  • Follow any instructions that the 911 operator gives you until the ambulance arrives.

What causes diabetes-related comas?

Three diabetes complications can lead to a coma if you don’t get proper treatment for them in time, including:

  • Hyperosmolar hyperglycemic state (HHS).
  • Diabetes-related ketoacidosis (DKA).
  • Severe low blood sugar (hypoglycemia).

HHS and DKA can both cause severe dehydration, which can trigger a coma. As your brain needs glucose to function, a severe lack of glucose from low blood sugar can cause your brain to “shut down” and go into a coma.

What are the risk factors for a diabetes-related coma?

Anyone who has diabetes — or undiagnosed diabetes — is at risk for a diabetes-related coma. But the increased risks for specific causes depend on the type of diabetes:

  • People with Type 1 diabetes have a greater chance of going into a diabetes-related coma from DKA or severe low blood sugar. This is because people with Type 1 diabetes always need 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 diabetes-related coma from HHS than DKA or severe low blood sugar.

Other factors that may increase your risk include:

  • Illness.
  • Surgery.
  • Trauma.
  • Insulin delivery problems.
  • Forgetting/skipping one or more doses of insulin or taking too much insulin.
  • Undermanaging diabetes, like not knowing your blood sugar levels day to day or not taking medication regularly.
  • Hypoglycemia unawareness (not experiencing typical symptoms of mild to moderate low blood sugar).
  • Drinking alcohol.
  • Substance use.


Diagnosis and Tests

How is a diabetes-related coma diagnosed?

A diabetes-related coma is a medical emergency. Anyone in a coma needs treatment in a hospital.

Healthcare providers can usually quickly diagnose a diabetes-related coma by knowing your medical history and doing a blood glucose test. They’ll perform other tests, too, like tests to check for ketones and your overall health.

This is why it’s important to wear a medical alert bracelet or necklace — providers can find this quickly in cases of emergencies. It’s also important to tell loved ones, coworkers and acquaintances that you have diabetes, so they know what to do in case you experience complications.

Management and Treatment

How is a diabetes-related coma treated?

The treatment for a diabetes-related coma depends on the cause. But all cases need treatment in a hospital.

Treatment for a diabetes-related coma due to DKA or HHS includes:

  • IV fluids: IV fluids help correct dehydration and electrolyte imbalances.
  • Insulin: Your healthcare team may give you insulin through an IV or as a needle injection (subcutaneous shot).
  • Other treatments: Your healthcare team may give you other treatments to help you recover. They’ll treat any underlying conditions or infections that may have caused high blood sugar.

Treatment for diabetes-related coma due to severe low blood sugar includes:

  • Emergency glucagon: This is a synthetic form of glucagon that a loved one or provider can administer as an injection or nasal powder (dry nasal spray), depending on the type. Synthetic glucagon triggers your liver to release stored glucose, which then raises blood sugar. If a loved one gives you glucagon, you still need medical treatment in a hospital. They should give you the glucagon and call 911.

You may need additional medical treatments for any further complications, like organ failure.

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How can I prevent a diabetes-related coma?

It’s crucial to know the early warning signs of DKA, HHS and low blood sugar to prevent a diabetes-related coma. Educate yourself and talk to your healthcare provider about the plan of action you need to take to treat these conditions before they become worse.

Call a healthcare provider in the following situations:

  • If your blood sugar is 300 mg/dL or higher two times in a row for an unknown reason.
  • If you have a low blood sugar episode (less than 70 mg/dL) that has not come up after three treatments, call your healthcare provider or 911.

Outlook / Prognosis

Can someone survive a diabetes-related coma?

Yes, it’s possible to survive a diabetes-related coma if you get treatment for the underlying cause. But some people have permanent brain damage. If you don’t get proper treatment in time, you can die.

DKA has a mortality (death) rate of 0.2% to 2.5%. People who go into a coma, have hypothermia (low body temperature) and have low pee output (oliguria) tend to have the worst outcomes.

Up to 20% of people who have HHS die from the condition. People who develop coma and/or low blood pressure have a poorer prognosis (outlook).

How long can you be in a diabetes-related coma?

The length of a diabetes-related coma depends largely on how quickly you receive proper treatment. The only possible way to end this kind of coma is to return to healthy blood glucose and insulin levels, which only happens with treatment by medical professionals. A person in a diabetes-related coma will not come out of it on their own.

If a person in this kind of coma doesn’t receive treatment in time, they’ll likely die. “In time” varies based on the situation and person. This is why it’s essential to get help as soon as possible.

A note from Cleveland Clinic

Diabetes-related comas are often preventable. The key is knowing the warning signs of DKA (diabetes-related ketoacidosis), HHS (hyperosmolar hyperglycemic state) and low blood sugar and acting fast to correct them. Be sure to call your healthcare provider if you experience symptoms of any of these conditions. Diabetes complications can be scary. Being educated and prepared are crucial to preventing them. Don’t hesitate to ask your provider questions about them or your diabetes management.

Medically Reviewed

Last reviewed on 10/20/2023.

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