Diabetic coma

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Diabetic coma
Blue circle for diabetes.svg
Universal blue circle symbol for diabetes. [1]
Specialty Endocrinology

Diabetic coma is a life-threatening but reversible form of coma found in people with diabetes mellitus. [2]


Three different types of diabetic coma are identified: [3]

  1. Severe low blood sugar in a diabetic person
  2. Diabetic ketoacidosis (usually type 1) advanced enough to result in unconsciousness from a combination of a severely increased blood sugar level, dehydration and shock, and exhaustion
  3. Hyperosmolar nonketotic coma (usually type 2) in which an extremely high blood sugar level and dehydration alone are sufficient to cause unconsciousness.

In most medical contexts, the term diabetic coma refers to the diagnostical dilemma posed when a physician is confronted with an unconscious patient about whom nothing is known except that they have diabetes. An example might be a physician working in an emergency department who receives an unconscious patient wearing a medical identification tag saying DIABETIC. Paramedics may be called to rescue an unconscious person by friends who identify them as diabetic. Brief descriptions of the three major conditions are followed by a discussion of the diagnostic process used to distinguish among them, as well as a few other conditions which must be considered.

An estimated 2 to 15 percent of people with diabetes will have at least one episode of diabetic coma in their lifetimes as a result of severe hypoglycemia. [4]


Severe hypoglycemia

People with type 1 diabetes mellitus who must take insulin in full replacement doses are most vulnerable to episodes of hypoglycemia (low blood glucose levels). This can occur if a person takes too much insulin or diabetic medication, does strenuous exercise without eating additional food, misses meals, consumes too much alcohol, or consumes alcohol without food. [5] It is usually mild enough to reverse by eating or drinking carbohydrates, but blood glucose occasionally can fall fast enough and low enough to produce unconsciousness before hypoglycemia can be recognized and reversed. Hypoglycemia can be severe enough to cause unconsciousness during sleep. Predisposing factors can include eating less than usual or prolonged exercise earlier in the day. Some people with diabetes can lose their ability to recognize the symptoms of early hypoglycemia.

Unconsciousness due to hypoglycemia can occur within 20 minutes to an hour after early symptoms and is not usually preceded by other illness or symptoms. Twitching or convulsions may occur. A person unconscious from hypoglycemia is usually pale, has a rapid heart beat, and is soaked in sweat: all signs of the adrenaline response to hypoglycemia. The individual is not usually dehydrated and breathing is normal or shallow. Their blood sugar level, measured by a glucose meter or laboratory measurement at the time of discovery, is usually low but not always severely, and in some cases may have already risen from the nadir that triggered the unconsciousness.

Unconsciousness due to hypoglycemia is treated by raising the blood glucose with intravenous glucose or injected glucagon.

Advanced diabetic ketoacidosis

Diabetic ketoacidosis (DKA), most typically seen in those with type 1 diabetes, is triggered by the build-up of chemicals called ketones. These are strongly acidic and a build-up can cause the blood to become acidic. [5] When these levels get too high it essentially poisons the body and causes DKA. [6]

If it progresses and worsens without treatment it can eventually cause unconsciousness, from a combination of a very high blood sugar level, dehydration and shock, and exhaustion. Coma only occurs at an advanced stage, usually after 36 hours or more of worsening vomiting and hyperventilation.

In the early to middle stages of ketoacidosis, patients are typically flushed and breathing rapidly and deeply, but visible dehydration, pale appearance from diminished perfusion, shallower breathing, and a fast heart rate are often present when coma is reached. However these features are variable and not always as described.

If the patient is known to have diabetes, the diagnosis of diabetic ketoacidosis is usually suspected from the appearance and a history of 1–2 days of vomiting. The diagnosis is confirmed when the usual blood chemistries in the emergency department reveal a high blood sugar level and severe metabolic acidosis.

Treatment of diabetic ketoacidosis consists of isotonic fluids to rapidly stabilize the circulation, continued intravenous saline with potassium and other electrolytes to replace deficits, insulin to reverse the ketoacidosis, and careful monitoring for complications.

Nonketotic hyperosmolar coma

Nonketotic hyperosmolar coma usually develops more insidiously than diabetic ketoacidosis because the principal symptom is lethargy progressing to obtundation, rather than vomiting and an obvious illness. Extremely high blood sugar levels are accompanied by dehydration due to inadequate fluid intake. Coma occurs most often in patients who have type 2 or steroid diabetes and have an impaired ability to recognize thirst and drink. It is classically a nursing home condition but can occur in all ages.

The diagnosis is usually discovered when a chemistry screen performed because of obtundation reveals an extremely high blood sugar level (often above 1800 mg/dl (100 mM)) and dehydration. The treatment consists of insulin and gradual rehydration with intravenous fluids.

Identifying the cause

Diabetic coma was a more significant diagnostic problem before the late 1970s, when glucose meters and rapid blood chemistry analyzers were not available in all hospitals. In modern medical practice, it rarely takes more than a few questions, a quick look, and a glucose meter to determine the cause of unconsciousness in a patient with diabetes. Laboratory confirmation can usually be obtained in half an hour or less. Other conditions that can cause unconsciousness in a person with diabetes are stroke, uremic encephalopathy, alcohol, drug overdose, head injury, or seizure.

Most patients do not reach the point of unconsciousness or coma in cases of diabetic hypoglycemia, diabetic ketoacidosis, or severe hyperosmolarity before a family member or caretaker seeks medical help.


Treatment depends upon the underlying cause: [7]

Related Research Articles

Hypoglycemia Not enough blood sugar, usually because of temporary overcorrection of diabetes

Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose below 70 mg/dL (3.9 mmol/L), symptoms associated with hypoglycemia, and resolution of symptoms when blood sugar returns to normal. Hypoglycemia may result in headache, tiredness, clumsiness, trouble talking, confusion, fast heart rate, sweating, shakiness, nervousness, hunger, loss of consciousness, seizures, or death. Symptoms typically come on quickly.

The following is a glossary of diabetes which explains terms connected with diabetes.

Diabetic ketoacidosis Medical condition

Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes mellitus. Signs and symptoms may include vomiting, abdominal pain, deep gasping breathing, increased urination, weakness, confusion and occasionally loss of consciousness. A person's breath may develop a specific "fruity" smell. Onset of symptoms is usually rapid. People without a previous diagnosis of diabetes may develop DKA as the first obvious symptom.

Hyperglycemia Too much blood sugar, usually because of diabetes

Hyperglycemia is a condition in which an excessive amount of glucose circulates in the blood plasma. This is generally a blood sugar level higher than 11.1 mmol/l (200 mg/dL), but symptoms may not start to become noticeable until even higher values such as 13.9–16.7 mmol/l (~250–300 mg/dL). A subject with a consistent range between ~5.6 and ~7 mmol/l is considered slightly hyperglycemic, and above 7 mmol/l is generally held to have diabetes. For diabetics, glucose levels that are considered to be too hyperglycemic can vary from person to person, mainly due to the person's renal threshold of glucose and overall glucose tolerance. On average, however, chronic levels above 10–12 mmol/L (180–216 mg/dL) can produce noticeable organ damage over time.

Ketoacidosis Medical condition

Ketoacidosis is a metabolic state caused by uncontrolled production of ketone bodies that cause a metabolic acidosis. While ketosis refers to any elevation of blood ketones, ketoacidosis is a specific pathologic condition that results in changes in blood pH and requires medical attention. The most common cause of ketoacidosis is diabetic ketoacidosis but can also be caused by alcohol, medications, toxins, and rarely starvation.

Alcoholic ketoacidosis Medical condition

Alcoholic ketoacidosis (AKA) is a specific group of symptoms and metabolic state related to alcohol use. Symptoms often include abdominal pain, vomiting, agitation, a fast respiratory rate, and a specific "fruity" smell. Consciousness is generally normal. Complications may include sudden death.

Hyperinsulinemic hypoglycemia describes the condition and effects of low blood glucose caused by excessive insulin. Hypoglycemia due to excess insulin is the most common type of serious hypoglycemia. It can be due to endogenous or injected insulin.

Neuroglycopenia is a shortage of glucose (glycopenia) in the brain, usually due to hypoglycemia. Glycopenia affects the function of neurons, and alters brain function and behavior. Prolonged or recurrent neuroglycopenia can result in loss of consciousness, damage to the brain, and eventual death.

Diabetes mellitus is a chronic disease in cats whereby either insufficient insulin response or insulin resistance leads to persistently high blood glucose concentrations. Diabetes affects up to 1 in 230 cats, and may be becoming increasingly common. Diabetes mellitus is less common in cats than in dogs. Eighty to ninety-five percent of diabetic cats experience something similar to type 2 diabetes but are generally severely insulin dependent by the time symptoms are diagnosed. The condition is treatable, and if treated properly the cat can experience a normal life expectancy. In type 2 cats, prompt effective treatment may lead to diabetic remission, in which the cat no longer needs injected insulin. Untreated, the condition leads to increasingly weak legs in cats and eventually to malnutrition, ketoacidosis and/or dehydration, and death.

Diabetic hypoglycemia Medical condition

Diabetic hypoglycemia is a low blood glucose level occurring in a person with diabetes mellitus. It is one of the most common types of hypoglycemia seen in emergency departments and hospitals. According to the National Electronic Injury Surveillance System-All Injury Program (NEISS-AIP), and based on a sample examined between 2004 and 2005, an estimated 55,819 cases involved insulin, and severe hypoglycemia is likely the single most common event.

Steroid diabetes is a medical term referring to prolonged hyperglycemia due to glucocorticoid therapy for another medical condition. It is usually, but not always, a transient condition.

Type 1 diabetes Form of diabetes mellitus

Type 1 diabetes (T1D), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin are destroyed by the immune system. Insulin is a hormone required for the cells to use blood sugar for energy and it helps regulate normal glucose levels in the bloodstream. Before treatment this results in high blood sugar levels in the body. The common symptoms of this elevated blood sugar are frequent urination, increased thirst, increased hunger, weight loss, and other serious complications. Additional symptoms may include blurry vision, tiredness, and slow wound healing. Symptoms typically develop over a short period of time, often a matter of weeks.

The term diabetes includes several different metabolic disorders that all, if left untreated, result in abnormally high concentration of a sugar called glucose in the blood. Diabetes mellitus type 1 results when the pancreas no longer produces significant amounts of the hormone insulin, usually owing to the autoimmune destruction of the insulin-producing beta cells of the pancreas. Diabetes mellitus type 2, in contrast, is now thought to result from autoimmune attacks on the pancreas and/or insulin resistance. The pancreas of a person with type 2 diabetes may be producing normal or even abnormally large amounts of insulin. Other forms of diabetes mellitus, such as the various forms of maturity onset diabetes of the young, may represent some combination of insufficient insulin production and insulin resistance. Some degree of insulin resistance may also be present in a person with type 1 diabetes.

Hyperosmolar hyperglycemic state (HHS) is a complication of diabetes mellitus in which high blood sugar results in high osmolarity without significant ketoacidosis. Symptoms include signs of dehydration, weakness, leg cramps, vision problems, and an altered level of consciousness. Onset is typically over days to weeks. Complications may include seizures, disseminated intravascular coagulopathy, mesenteric artery occlusion, or rhabdomyolysis.

Complications of diabetes mellitus include problems that develop rapidly (acute) or over time (chronic) and may affect many organ systems. The complications of diabetes can dramatically impair quality of life and cause long-lasting disability. Overall, complications are far less common and less severe in people with well-controlled blood sugar levels. Some non-modifiable risk factors such as age at diabetes onset, type of diabetes, gender and genetics may influence risk. Other health problems compound the chronic complications of diabetes such as smoking, obesity, high blood pressure, elevated cholesterol levels, and lack of regular exercise. Complications of diabetes are a strong risk factor for severe COVID-19 illness.

Diabetes in dogs

Diabetes mellitus is a disease in which the beta cells of the endocrine pancreas either stop producing insulin or can no longer produce it in enough quantity for the body's needs. The disease can affect humans as well as animals such as dogs.

Dysglycemia is a general definition for any abnormalities in blood glucose levels. They include hyperglycemia, hypoglycemia, impaired glucose tolerance test, impaired fasting glucose, among others.

Diabetes usually refers to diabetes mellitus, a group of metabolic diseases in which a person has high blood glucose levels over a prolonged period.

Empagliflozin, sold under the brand name Jardiance among others, is an antidiabetic medication used to improve glucose control in people with type 2 diabetes, used to reduce the risk of cardiovascular death in adults with type 2 diabetes and established cardiovascular disease, used to reduce the risk of death and hospitalization in people with heart failure and low ejection fraction, and used to reduce the risk of cardiovascular death and hospitalization for heart failure in adults. It can be prescribed instead of metformin and has benefits over sulfonylureas. It may be used together with other medications such as metformin or insulin. It is not recommended for type 1 diabetes. It is taken by mouth.

Ketosis-prone diabetes (KPD) is an intermediate form of diabetes that has some characteristics of type 1 and some of type 2 diabetes. Type 1 diabetes involves autoimmune destruction of pancreatic beta cells which create insulin. This occurs earlier in a person's life, leading to patients being insulin dependent, and the lack of natural insulin makes patients prone to a condition called diabetic ketoacidosis (DKA). Type 2 diabetes is different in that it is usually caused by insulin resistance in the body in older patients leading to beta cell burnout over time, and is not prone to DKA. KPD is a condition that involves DKA like type 1, but occurs later in life and can regain beta cell function like type 2 diabetes. However, it is distinct from latent autoimmune diabetes of adults (LADA), a form of type 1 sometimes referred to as type 1.5 that does not occur with DKA. There are also distinctions to be made between KPD and LADA as patients who exhibit KPD symptoms can regain beta cell function similar to type 2 diabetics whereas LADA will not exhibit this reclamation of beta cell function.


  1. "Diabetes Blue Circle Symbol". International Diabetes Federation. 17 March 2006. Archived from the original on 5 August 2007.
  2. Richard S. Irwin; James M. Rippe (2008). Irwin and Rippe's intensive care medicine. Lippincott Williams & Wilkins. pp. 1256–. ISBN   978-0-7817-9153-3 . Retrieved 20 November 2010.
  3. "Diabetic coma - Symptoms and causes". Mayo Clinic. Retrieved 2021-12-27.
  4. "Study: Glucose byproduct may prevent brain damage & impairment after diabetic coma". UCSF Medical Center. Retrieved 4 October 2020.
  5. 1 2 "Diabetic coma - Better Health Channel". www.betterhealth.vic.gov.au. Retrieved 2021-12-27.
  6. "DKA (Ketoacidosis) & Ketones | ADA". www.diabetes.org. Retrieved 2021-12-27.
  7. "Diabetic Coma: Causes, Risk Factors, Treatment & Prevention". Cleveland Clinic. Retrieved 2021-12-27.