Diabetic ketoacidosis is a potentially life-threatening complication in patients with diabetes mellitus.
It happens predominantly in those with type 1 diabetes, but it can occur in those with
type 2 diabetes under certain circumstances. DKA results from a shortage of insulin; in
response the body switches to burning fatty acids and producing acidic ketone bodies that
cause most of the symptoms and complications. DKA may be the first symptom of previously
undiagnosed diabetes, but it may also occur in people known to have diabetes as a result
of a variety of causes, such as intercurrent illness or poor compliance with insulin therapy.
Vomiting, dehydration, deep gasping breathing, confusion and occasionally coma are typical
symptoms. DKA is diagnosed with blood and urine tests; it is distinguished from other,
rarer forms of ketoacidosis by the presence of high blood sugar levels. Treatment involves
intravenous fluids to correct dehydration, insulin to suppress the production of ketone
bodies, treatment for any underlying causes such as infections, and close observation
to prevent and identify complications. DKA is a medical emergency, and without treatment
it can lead to death. DKA was first described in 1886; until the introduction of insulin
therapy in the 1920s it was almost universally fatal. It now carries a mortality of less
than 1% with adequate and timely treatment.
Signs and symptoms The symptoms of an episode of diabetic ketoacidosis
usually evolve over the period of about 24 hours. Predominant symptoms are nausea and
vomiting, pronounced thirst, excessive urine production and abdominal pain that may be
severe. Those who measure their glucose levels themselves may notice hyperglycemia. In severe
DKA, breathing becomes labored and of a deep, gasping character. The abdomen may be tender
to the point that an acute abdomen may be suspected, such as acute pancreatitis, appendicitis
or gastrointestinal perforation. Coffee ground vomiting occurs in a minority of patients;
this tends to originate from erosion of the esophagus. In severe DKA, there may be confusion,
lethargy, stupor or even coma. On physical examination there is usually clinical
evidence of dehydration, such as a dry mouth and decreased skin turgor. If the dehydration
is profound enough to cause a decrease in the circulating blood volume, tachycardia
and low blood pressure may be observed. Often, a "ketotic" odor is present, which is often
described as "fruity", often compared to the smell of pear drops whose scent is a ketone.
If Kussmaul respiration is present, this is reflected in an increased respiratory rate.
Small children with DKA are relatively prone to cerebral edema, which may cause headache,
coma, loss of the pupillary light reflex, and progress to death. It occurs in 0.3–1.0%
of children with DKA, and has been described in young adults, but is overall very rare
in adults. It carries a 20–50% mortality. Cause
DKA most frequently occurs in those who already have diabetes, but it may also be the first
presentation in someone who had not previously been known to be diabetic. There is often
a particular underlying problem that has led to the DKA episode; this may be intercurrent
illness, pregnancy, inadequate insulin administration, myocardial infarction, stroke or the use of
cocaine. Young patients with recurrent episodes of DKA may have an underlying eating disorder,
or may be using insufficient insulin for fear that it will cause weight gain.
Diabetic ketoacidosis may occur in those previously known to have diabetes mellitus type 2 or
in those who on further investigations turn out to have features of type 2 diabetes; this
is more common in African, African-American and Hispanic people. Their condition is then
labeled "ketosis-prone type 2 diabetes". Mechanism
Diabetic ketoacidosis arises because of a lack of insulin in the body. The lack of insulin
and corresponding elevation of glucagon leads to increased release of glucose by the liver
from glycogen via glycogenolysis and also through gluconeogenesis. High glucose levels
spill over into the urine, taking water and solutes along with it in a process known as
osmotic diuresis. This leads to polyuria, dehydration, and compensatory thirst and polydipsia.
The absence of insulin also leads to the release of free fatty acids from adipose tissue, which
are converted, again in the liver, into ketone bodies. β-Hydroxybutyrate can serve as an
energy source in the absence of insulin-mediated glucose delivery, and is a protective mechanism
in case of starvation. The ketone bodies, however, have a low pKa and therefore turn
the blood acidic. The body initially buffers the change with the bicarbonate buffering
system, but this system is quickly overwhelmed and other mechanisms must work to compensate
for the acidosis. One such mechanism is hyperventilation to lower the blood carbon dioxide levels.
This hyperventilation, in its extreme form, may be observed as Kussmaul respiration.
In various situations such as infection, insulin demands rise but are not matched by the failing
pancreas. Blood sugars rise, dehydration ensues, and resistance to the normal effects of insulin
increases further by way of a vicious circle. As a result of the above mechanisms, the average
adult DKA patient has a total body water shortage of about 6 liters, in addition to substantial
shortages in sodium, potassium, chloride, phosphate, magnesium and calcium. Glucose
levels usually exceed 13.8 mmol/L or 250 mg/dL.
DKA is common in type 1 diabetes as this form of diabetes is associated with an absolute
lack of insulin production by the islets of Langerhans. In type 2 diabetes, insulin production
is present but is insufficient to meet the body's requirements as a result of end-organ
insulin resistance. Usually, these amounts of insulin are sufficient to suppress ketogenesis.
If DKA occurs in someone with type 2 diabetes, their condition is called "ketosis-prone type
2 diabetes". The exact mechanism for this phenomenon is unclear, but there is evidence
both of impaired insulin secretion and insulin action. Once the condition has been treated,
insulin production resumes and often the patient may be able to resume diet or tablet treatment
as normally recommended in type 2 diabetes. The clinical state of DKA is associated, in
addition to the above, with the release of various counterregulatory hormones such as
glucagon and adrenaline as well as cytokines, the latter of which leads to increased markers
of inflammation, even in the absence of infection. Cerebral edema, which is the most dangerous
DKA complication, is probably the result of a number of factors. Some authorities suggest
that it is the result from overvigorous fluid replacement, but the complication may develop
before treatment has been commenced. It is more likely in those with more severe DKA,
and in the first episode of DKA. Likely factors in the development of cerebral edema are dehydration,
acidosis and low carbon dioxide levels; in addition, the increased level of inflammation
and coagulation may, together with these factors, lead to decreased blood flow to parts of the
brain, which then swells up once fluid replacement has been commenced. The swelling of brain
tissue leads to raised intracranial pressure ultimately leading to death.
Diagnosis Investigations
Diabetic ketoacidosis may be diagnosed when the combination of hyperglycemia, ketones
in the blood or on urinalysis and acidosis are demonstrated. Arterial blood gas measurement
is usually performed to demonstrate the acidosis; this requires taking a blood sample from an
artery. Subsequent measurements, may be taken from a normal blood test taken from a vein,
as there is little difference between the arterial and the venous pH.
In addition to the above, blood samples are usually taken to measure urea and creatinine
and electrolytes. Furthermore, markers of infection and acute pancreatitis may be measured.
Given the need to exclude infection, chest radiography and urinalysis are usually performed.
If cerebral edema is suspected because of confusion, recurrent vomiting or other symptoms,
computed tomography may be performed to assess its severity and to exclude other causes such
as stroke. Criteria
Diabetic ketoacidosis is distinguished from other diabetic emergencies by the presence
of large amounts of ketones in blood and urine, and marked metabolic acidosis. Hyperosmolar
hyperglycemic state is much more common in type 2 diabetes and features increased plasma
osmolarity due to profound dehydration and concentration of the blood; mild acidosis
and ketonemia may occur in this state, but not to the extent observed in DKA. There is
a degree of overlap between DKA and HHS, as in DKA the osmolarity may also be increased.
Ketoacidosis is not always the result of diabetes. It may also result from alcohol excess and
from starvation; in both states the glucose level is normal or low. Metabolic acidosis
may occur in people with diabetes for other reasons, such as poisoning with ethylene glycol
or paraldehyde. The American Diabetes Association categorizes
DKA in adults into one of three stages of severity:
Mild: blood pH mildly decreased to between 7.25 and 7.30; serum bicarbonate decreased
to 15–18 mmol/l; the patient is alert Moderate: pH 7.00–7.25, bicarbonate 10–15,
mild drowsiness may be present Severe: pH below 7.00, bicarbonate below 10,
stupor or coma may occur A 2004 statement by the European Society for
Paediatric Endocrinology and the Lawson Wilkins Pediatric Endocrine Society uses slightly
different cutoffs, where mild DKA is defined by pH 7.20–7.30, moderate DKA by pH 7.1–7.2
and severe DKA by pH<7.1. Prevention
Attacks of DKA can be prevented in those known to have diabetes to an extent by adherence
to "sick day rules"; these are clear-cut instructions to patients on how to treat themselves when
unwell. Instructions include advice on how much extra insulin to take when sugar levels
appear uncontrolled, an easily digestible diet rich in salt and carbohydrates, means
to suppress fever and treat infection, and recommendations when to call for medical help.
Management The main aims in the treatment of diabetic
ketoacidosis are replacing the lost fluids and electrolytes while suppressing the high
blood sugars and ketone production with insulin. Admission to an intensive care unit or similar
high-dependency area or ward for close observation may be necessary.
Fluid replacement The amount of fluid replaced depends on the
estimated degree of dehydration. If dehydration is so severe as to cause shock, or a depressed
level of consciousness, rapid infusion of saline is recommended to restore circulating
volume. Slower rehydration based on calculated water and sodium shortage may be possible
if the dehydration is moderate, and again saline is the recommended fluid. Very mild
ketoacidosis with no associated vomiting and mild dehydration may be treated with oral
rehydration and subcutaneous rather than intravenous insulin under observation for signs of deterioration.
A special but unusual consideration is cardiogenic shock, where the blood pressure is decreased
not due to dehydration but due to inability of the heart to pump blood through the blood
vessels. This situation requires ICU admission, monitoring of the central venous pressure,
and the administration of medication that increases the heart pumping action and blood
pressure. Insulin
Some guidelines recommend a bolus of insulin of 0.1 unit of insulin per kilogram of body
weight. This can be administered immediately after the potassium level is known to be higher
than 3.3 mmol/l; if the level is any lower, administering insulin could lead to a dangerously
low potassium level. Other guidelines recommend delaying the initiation of insulin until fluids
have been administered. In general, insulin is given at 0.1 unit/kg
per hour to reduce the blood sugars and suppress ketone production. Guidelines differ as to
which dose to use when blood sugar levels start falling; some recommend reducing the
dose of insulin once glucose falls below 16.6 mmol/l but other recommend infusing glucose in addition
to saline to allow for ongoing infusion of higher doses of insulin.
Potassium Potassium levels can fluctuate severely during
the treatment of DKA, because insulin decreases potassium levels in the blood by redistributing
it into cells. A large part of the shifted extracellular potassium would have been lost
in urine because of osmotic diuresis. Hypokalemia often follows treatment. This increases the
risk of dangerous irregularities in the heart rate. Therefore, continuous observation of
the heart rate is recommended, as well as repeated measurement of the potassium levels
and addition of potassium to the intravenous fluids once levels fall below 5.3 mmol/l.
If potassium levels fall below 3.3 mmol/l, insulin administration may need to be interrupted
to allow correction of the hypokalemia. Bicarbonate
The administration of sodium bicarbonate solution to rapidly improve the acid levels in the
blood is controversial. There is little evidence that it improves outcomes beyond standard
therapy, and indeed some evidence that while it may improve the acidity of the blood, it
may actually worsen acidity inside the body's cells and increase the risk of certain complications.
Its use is therefore discouraged, although some guidelines recommend it for extreme acidosis,
and smaller amounts for severe acidosis. Cerebral edema
Cerebral edema, if associated with coma, often necessitates admission to intensive care,
artificial ventilation, and close observation. The administration of fluids is slowed. The
ideal treatment of cerebral edema in DKA is not established, but intravenous mannitol
and hypertonic saline are used—as in some other forms of cerebral edema—in an attempt
to reduce the swelling. Resolution
Resolution of DKA is defined as general improvement in the symptoms, such as the ability to tolerate
oral nutrition and fluids, normalization of blood acidity, and absence of ketones in blood
or urine. Once this has been achieved, insulin may be switched to the usual subcutaneously
administrered regimen, one hour after which the intravenous administration can be discontinued.
In patients with suspected ketosis-prone type 2 diabetes, determination of antibodies against
glutamic acid decarboxylase and islet cells may aid in the decision whether to continue
insulin administration long-term, or whether to withdraw insulin and attempt treatment
with oral medication as in type 2 diabetes. Epidemiology
Diabetic ketoacidosis occurs in 4.6–8.0 per 1000 people with type 1 diabetes annually.
In the United States, 135,000 hospital admissions occur annually as a result of DKA, at an estimated
cost of $2.4 billion or a quarter to a half the total cost of caring for people with type
1 diabetes. There has been a documented increasing trend to hospital admissions. The risk is
increased in those with an ongoing risk factor, such as an eating disorder, and those who
cannot afford insulin. About 30% of children with type 1 diabetes receive their diagnosis
after an episode of DKA. History
The first full description of diabetic ketoacidosis is attributed to Julius Dreschfeld, a German
pathologist working in Manchester, United Kingdom. In his description, which he gave
in an 1886 lecture at the Royal College of Physicians in London, he drew on reports by
Adolph Kussmaul as well as describing the main ketones, acetoacetate and β-hydroxybutyrate,
and their chemical determination. The condition remained almost universally fatal until the
discovery of insulin in the 1920s; by the 1930s, mortality had fallen to 29%, and by
the 1950s it had become less than 10%. The entity of cerebral edema due to DKA was described
in 1936 by a team of doctors from Philadelphia. Numerous research studies since the 1950s
have focused on the ideal treatment for diabetic ketoacidosis. A significant proportion of
these studies have been conducted at the University of Tennessee Health Science Center and Emory
University School of Medicine. Treatment options studied have included high- or low-dose intravenous,
subcutaneous or intramuscular insulin, phosphate supplementation, need for a loading dose of
insulin, and appropriateness of using bicarbonate therapy in moderate DKA. Various questions
remain unanswered, such as whether bicarbonate administration in severe DKA makes any real
difference to the clinical course, and whether an insulin loading dose is needed in adults.
The entity of ketosis-prone type 2 diabetes was first fully described in 1987 after several
preceding case reports. It was initially thought to be a form of maturity onset diabetes of
the young, and went through several other descriptive names before the current terminology
of "ketosis-prone type 2 diabetes" was adopted. References