Diabetic Coma

Diabetic Coma

Also called: Nonketotic Coma, Hypoglycemic Coma, Hyperosmolar Coma, Hyperglycemic Coma


Diabetic coma is a state of unconsciousness that can put a patient at risk of brain damage or even death. It is triggered by either persistent and extreme elevations in glucose (blood sugar) levels (hyperglycemia) or abnormally low glucose levels (hypoglycemia).

A person in a diabetic coma is still breathing but has impaired brain function that keeps the individual unconscious and unable to communicate. Prompt treatment is necessary to prevent long-term, irreversible damage and return the individual to consciousness. In rare cases, delayed treatment can result in death. In some cases, patients will emerge from the coma and make varying degrees of recovery. Some will have permanent brain damage, but others will recover completely. In general, the longer patients are in a comatose state, the more likely they are to suffer severe, permanent brain damage or death.

Controlling glucose is the best way to prevent diabetic coma. Patients should consult with a physician about their appropriate glucose level and closely monitor this level to make sure it is not too high or too low. Changes in diet, exercise and medication may be necessary to manage glucose. A sick-day plan devised by a physician can also help prevent diabetic coma.

About diabetic coma

Diabetic coma is a condition in which a patient loses consciousness because of excessively high or excessively low glucose (blood sugar). A person in a diabetic coma is still breathing but is in a profound state of unconsciousness and cannot be aroused by stimuli.

A coma is a deep, prolonged state of unconsciousness caused by an injury or disease. A region deep within the brain stem stimulates the brain to various levels of wakefulness and alertness, depending on signals received from the eyes, ears, skin and other sensory organs. When this area of the brain is disturbed, a person’s consciousness may be impaired.

In most cases, a diabetic coma lasts a few days. Rarely, some patients may remain in a persistent coma (sometimes called “awake coma”). Patients in this state may have open eyes, and they may make grunting sounds or other vocalizations. However, the higher brain functions are absent.

Patients who fall into a diabetic coma need prompt treatment to ensure that vital functions such as heart rate, blood pressure and body temperature are stabilized. Failure to do so can lead to long-term damage to the patient’s ability to function mentally and physiologically.  

The damage associated with a diabetic coma will depend on how extensively the coma has injured the brain. In many cases, patients make full recoveries. Some patients, however, may have varying degrees of lingering psychological or physiological impairment.

In severe cases, diabetic coma can lead to death. However, the mortality rate may be declining. Deaths due to diabetic ketoacidosis and hyperosmolar hyperglycemic nonketotic syndrome, two of the potential causes of diabetic coma, fell from 42.4 to 23.8 for every 100,000 diabetic American adults between 1985 and 2002, the U.S. Centers for Disease Control and Prevention reported in 2006.

Types and differences of diabetic coma

A coma is defined as a state of profound unconsciousness (sometimes called an “altered” state of consciousness). Coma related to diabetes can have several causes. It may result from excessively high or low glucose (blood sugar).

The two types of diabetic coma that can result from high glucose levels (hyperglycemic) are diabetic ketoacidosis (DKA) and  hyperosmolar hyperglycemic nonketotic syndrome (HHNS).

DKA occurs when waste products of fat metabolism called ketones build up in the body. Blood glucose levels are very high during DKA, as well. The body may use body fat for energy if lack of insulin prevents it from using glucose. DKA can lead to diabetic coma and may be fatal when it does. People with type 1 diabetes have a greater chance of developing diabetic ketoacidosis than those with type 2 diabetes. Causes of diabetic ketoacidosis include:

  • Missed dose(s) of insulin
  • Acute infection or illness, such as pneumonia, heart attack or infection of an extremity (such as osteomyelitis or the skin disorder cellulitis)
  • Severe dehydration

HHNS involves very high glucose levels and dehydration.  It is generally not accompanied by a buildup of ketones. HHNS tends to affect older patients with type 2 diabetes and can lead to diabetic coma in rare situations. Causes of the syndrome include:

  • Missed dose(s) of insulin or other medication
  • Acute infection or illness
  • Increased intake of sugary foods or fluids

Low glucose (hypoglycemia) can cause a hypoglycemic coma. Hypoglycemia can develop suddenly but is often accompanied by warning symptoms such as sweating, rapid heart beat (palpitations), shakiness and dizziness. When untreated, hypoglycemia can affect the brain, leading to fainting and loss of consciousness or seizures. If a patient loses consciousness and is not promptly treated, brain damage can result. Causes of hypoglycemic coma include:

  • Extra or increased dose(s) of insulin or certain antidiabetic agents
  • Intense activity such as exercise without eating or medicating properly
  • Missing a snack or meal
  • Drinking too much alcohol, or drinking on an empty stomach

Symptoms and diagnosis of diabetic coma

Diabetic coma is a result of very low or very high glucose (blood sugar). Therefore, symptoms related to hypoglycemia and hyperglycemia present the greatest indicator that a patient may be in danger of lapsing into a diabetic coma. Among the symptoms of low glucose are dizziness, rapid heart rate, fainting, fatigue and polyphagia (extreme hunger). Among the symptoms of high glucose are dehydration, fatigue, polydipsia (extreme thirst) and polyuria (excessive urination). In addition, patients experiencing diabetic ketoacidosis may have heavy, gasping, labored breathing, known as Kussmaul breathing.

A physician will perform a physical examination and if possible obtain a medical history to try to confirm the likely cause of the coma.

Tests that may be ordered include:

  • Glucose tests. These may reveal high or low glucose levels.
  • Electrolyte blood tests. These may reveal the presence of abnormal pH (acid buildup) or extreme dehydration.
  • Ketone tests. These urine tests or blood tests can detect high levels of ketones characteristic of diabetic ketoacidosis.
  • Brain scans. Imaging tests such as a CAT scan (computed axial tomography) MRI (magnetic resonance imaging) or PET scan (positron emission tomography) can reveal brain damage.
  • Electroencephalogram (EEG). This test detects abnormalities in the electrical activity of the brain.

Treatment options for diabetic coma

Experts from national organizations recommend several steps to take when dealing with an unresponsive person.  Diabetic individuals and their families should check with their physicians about specific steps to take in these situations. Included in the general recommendations are the following:

  • Phone an emergency number, such as 911 in the United States and some other nations.
  • Do not try to give food or drink to an unconscious person.
  • Follow instructions provided by the operator while waiting for the ambulance.
  • Do not give patients additional medications without the instructions of medical personnel.

Patients under the care of medical professionals are treated with the goal of reducing the potential for additional damage to the brain. Patients may be placed on a ventilator to help them breathe, and will be monitored to ensure that their muscles, tendons and ligaments remain flexible, that they receive adequate nutrition and that they do not come down with infections. In addition, they may receive the following treatments based on the type of coma:

  • Hyperglycemic comas (ketoacidotic and hyperosmolar)
    • Intravenous fluids
    • Insulin
    • Administration of electrolytes such as potassium and sodium
  • Hypoglycemic coma
    • Glucagon. A hormone that forces the liver to release glucose (blood sugar) into the bloodstream. Severe hypoglycemia can be treated with an injection of glucagon by either a medical professional or a trained layperson. Patients who lapse into a diabetic coma will be unable to self-administer an injection. If a physician prescribes glucagon as part of a sick-day plan, people who have daily contact with the patient should be trained in administering an injection before an emergency occurs.
    • Intravenous glucose

Scientists are focusing on preventing the brain damage that can result from diabetic coma. Studies on animals have found that pyruvate, a byproduct of sugar metabolism, can reduce brain injury from hypoglycemic coma. However, much more research would have to be done before this treatment may be an option in humans.

Prevention methods for diabetic coma

The best way to prevent diabetic coma is to keep glucose (blood sugar) levels well under control. There are several steps that are essential to the careful maintenance of diabetes. They include:

  • Create and maintain an appropriate meal plan. Patients should work with their physician and a registered dietitian on crafting and following a diet that controls their glucose. Lack of carbohydrates can trigger “starvation” ketosis, though this is often mild, and hypoglycemia, which may lead to coma.
  • Check levels of glucose and ketones. Patients should perform glucose monitoring and ketone testing regularly as advised by their physician. This will help to warn them when their glucose is either too high or too low, or when they are in danger of complications such as diabetic ketoacidosis or hyperosmolar hyperglycemic nonketotic syndrome.
  • Take medications carefully. Patients should always take their medications exactly as instructed by a physician. If treatments fail to control a patient’s diabetes, adjustments may be necessary. However, patients should not adjust dosages or quit taking medications without first consulting a physician.

Patients and physicians should also be alert to how nondiabetes drugs can affect glucose. For example, researchers in 2006 reported that some popular antibiotics can cause dangerously high or low glucose.

  • Establish a sick-day plan. A physician can devise a plan to help prevent illnesses from escalating to life-threatening complications.
  • Address dawn phenomenon and the Somogyi effect. Some patients are troubled by  rising levels of  glucose in the morning. A physician may recommend steps such as changing medication, snacking before bedtime or using an insulin pump.
  • Control unstable diabetes. This continues to be a difficult therapeutic goal in many cases. Options to improve glycemic management may include an insulin pump, pancreas transplant or islet cell transplant. A possible option that a physician may prescribe for patients with type 1 diabetes or type 2 diabetes who use insulin is a newer injected antidiabetic agent called pramlintide (Symlin).
  • Educate family, friends, co-workers and caregivers. Patients should teach those around them how to respond to diabetic emergencies such as a diabetic coma. This can be crucial to avoiding serious health consequences when diabetic individuals are unable to treat themselves. In the case of children, instruction should be provided to school and day-care employees, coaches, leaders of youth groups and so forth.
  • Keep an emergency source of sugar at hand. These quick fixes for hypoglycemia (low blood glucose) include glucose tablets, glucose gels, nondiet soft drinks, fruit juice, hard candies and sugar packets. Some physicians recommend that to avoid overtreating hypoglycemia and causing high blood glucose, it may help to eat an initial predetermined amount, then wait 10 or 15 minutes before deciding whether to eat any more. Fatty foods such as chocolate and ice cream are less desirable because the body does not absorb them as quickly.
  • Wear an ID bracelet or necklace that details the condition. Such jewelry can provide critical information to those who respond when a patient lapses into a diabetic coma.

Another possible option may be to get a diabetes assistance dog. Several organizations train dogs to sense dangerous changes in glucose and alert their diabetic owner. However, demand for these animals is reported to be far greater than the supply.

Questions for your doctor about diabetic coma

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about diabetic coma:

  1. Am I (or is a loved one) at risk of diabetic coma?
  2. Are there warning signs I should watch for?
  3. How is diabetic coma treated?
  4. Can you develop a sick-day plan for me?
  5. What should my emergency plan and kit include?
  6. Whom should I inform about the emergency plan and kit?
  7. Should anyone be trained in administering glucagon to me?
  8. At what level of blood sugar should I contact you? What levels of blood sugar require immediate action?
  9. What other steps can I take to prevent diabetic coma?
  10. What else should I know about diabetic coma if I have diabetes or a loved one does?
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