Symptoms of a Diabetic Coma

Having diabetes increases the risk of having too high or too low blood sugars, which can become dangerous.

In a person without diabetes, the body usually does a good job balancing blood sugar levels and keeping them in a healthy range.

In someone with diabetes, the pancreas doesn’t produce enough insulin, and the cells don’t respond to insulin as they should, or the liver might release too much stored sugar.

Many people take insulin to help manage their diabetes, which further increases the risk of getting low blood sugar. 

When blood sugar levels rise to extreme highs or lows, the person may slip into a diabetic coma, which is when they become unconscious.

Diabetic comas can be life-threatening, so it’s essential to know what can cause them so they can be prevented.

What are the symptoms leading up to a diabetic coma?

A diabetic coma occurs when blood glucose levels fall dangerously low or climb too high, resulting in the person losing consciousness.

If you fall into a diabetic coma and the cause of the coma isn’t promptly treated, it can become fatal. Some people may fall into a coma for a few hours, while others might be in a coma for longer.

It all depends on the severity of the cause of the coma and how quickly the patient receives medical treatment.

A primary goal of managing diabetes is keeping blood sugars in a healthy range, which is between 70-140 mg/dL (milligrams per deciliter). 

Coma related to hypoglycemia: Hypoglycemia is the term for low blood sugar level and occurs when blood sugar levels fall below 70 milligrams per deciliter.

There are different levels of hypoglycemia, which correlate with the severity of the hypoglycemic event.

  • Level 1 (mild) hypoglycemia: Blood glucose is less than 70 mg/dL but is 54 mg/dL or higher.

  • Level 2 (moderate) hypoglycemia: Blood glucose is less than 54 mg/dL.

  • And Level 3 (severe) hypoglycemia: A person cannot function because of mental or physical changes. They need help from another person. In this case, blood glucose is often below 40 mg/dL. Severe hypoglycemia is more likely to result in a diabetic coma, especially if it goes untreated.

The most common symptoms of hypoglycemia include feeling shaky and/or dizzy, sweating, hunger, irritability or moodiness, anxiety, nervousness, and having a headache.

Some people experience nocturnal hypoglycemia, which means it occurs overnight while sleeping, making it even more dangerous.

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Signs of nocturnal hypoglycemia include:

  • Damp sheets or nightclothes, due to sweat during sleep

  • Nightmares

  • Feeling tired, irritable, or confused after waking

If you don’t treat hypoglycemia, severe hypoglycemia can occur, which can lead to a diabetic coma.

Signs and symptoms of severe hypoglycemia include:

  • Clumsiness or jerky movements

  • Muscle weakness

  • Slurred speech or difficulty speaking

  • Blurry or double vision

  • Drowsiness

  • Confusion

  • Convulsions or seizures

  • Coma

  • Death

People who have had diabetes for a long time may not be as aware of the symptoms of hypoglycemia. This is hypoglycemia unawareness.

Having hypoglycemia unawareness is dangerous because they might not feel the symptoms until the hypoglycemic event becomes more severe, increasing the risk of a diabetic coma.

Coma due to high blood sugar. Hyperglycemia is the term for high blood sugar levels. Blood sugar levels over 200 mg/dL are high. But blood sugar levels resulting in a diabetic coma will be much higher, usually 400 mg/dL or more.

Those with type 1 diabetes can develop a serious condition called diabetic ketoacidosis, or DKA. DKA occurs when insulin levels fall so low that the body starts burning ketones for fuel instead of glucose.

Some of the warning signs of DKA include thirst or a very dry mouth, frequent urination, high blood sugar levels, and high levels of ketones in the urine. 

Other symptoms can appear as DKA worsens, such as constantly feeling tired; dry or flushed skin; nausea, vomiting, or abdominal pain; difficulty breathing; fruity odor on the breath (from the body burning ketones for fuel) and having a hard time paying attention/confusion.

People with type 2 diabetes may develop hyperglycemic hyperosmolar syndrome, or HHS. Especially if they have recently had a medically stressful event such as infection, heart attack, stroke, or recent surgery; are dehydrated; are older; have poor kidney function, or aren’t following their diabetes treatment plan.

Symptoms of hyperglycemic hyperosmolar syndrome include:

  • Blood sugar level of 600 milligrams per deciliter (mg/dL) or higher

  • Excessive thirst

  • Dry mouth

  • Increased urination

  • Warm, dry skin

  • Fever

  • Drowsiness, confusion

  • Hallucinations

  • Vision loss

  • Convulsions

  • Coma

What happens when you go into a diabetic coma?

If your severe high or low blood sugar causes a diabetic coma, you are alive but are unconscious. People in a diabetic coma can’t be awakened or respond to sights, sounds, or other types of stimulation.

If someone is in a diabetic coma for a long time or they don’t receive emergency medical care, they may develop permanent brain damage or even die. However, people who receive emergency treatment usually survive and make a full recovery.

People in a diabetic coma are treated in a hospital under close supervision of medical professionals.

For high blood sugar, insulin therapy is administered as well as intravenous fluids and other solutions to help the body recover.

For low blood sugar, a doctor may administer glucagon to help the liver release stored sugar. Or the patient may receive intravenous glucose to raise blood sugar levels.

People in a diabetic coma will be monitored closely until they recover and regain consciousness. From there, the length of their hospital stay will depend on how quickly they recover.

How long does it take to recover from a diabetic coma?

Most people will respond quickly to treatment and regain consciousness once correcting their blood sugar, especially if they receive prompt medical care.

People who have suffered a diabetic coma will likely be counseled on ways to prevent it from occurring in the future and might have their diabetes medications changed before they are released from the hospital.

They might also be referred to diabetes specialists such as endocrinologists and diabetes educators to help them change their care plan to help prevent future diabetes complications


A diabetic coma results from very high or very low blood sugar levels, resulting in a loss of consciousness. People in a diabetic coma are alive but aren’t conscious or able to respond to any stimulation.

Complications that result in very high blood sugar include diabetic ketoacidosis (DKA) in people with type 1 diabetes and hyperglycemic hyperosmolar syndrome (HHS) in those with type 2 diabetes.

Severe low blood sugar (hypoglycemia) can also cause a diabetic coma and occurs when blood sugar levels fall below 40 mg/dL, though this threshold may vary among people.

Most people fully recover from a diabetic coma. Especially if they receive emergency medical care once they notice their symptoms. However, if medical care isn’t sought quickly, the likelihood of permanent brain damage and even death may occur once someone falls into a diabetic coma.

Managing blood sugars while following a personalized diabetes care plan is the best strategy to prevent diabetic comas.

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  1. SingleCare Team. (2020) What should my blood sugar level be? Available at:
  2. Hormone Health Network.”Severe Hypoglycemia | Hormone Health Network.”, Endocrine Society, 21 April 2021,
  3. National Institute of Diabetes and Digestive and Kidney Diseases (2016) Low Blood Glucose (Hypoglycemia). Available at:
  4. Johns Hopkins Medicine. Hypoglycemia: Nocturnal. Available at:
  5. American Diabetes Association. DKA (Ketoacidosis) & Ketones. Available at:

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