The Pathophysiology of Diabetic Ketoacidosis
Diabetic ketoacidosis is a manifestation of untreated
type 1 diabetes. It occurs when there is an insulin deficit that causes fat
stores to break down, resulting in continued hyperglycemia and mobilization
of fatty acids with a subsequent ketosis.
Diabetic ketoacidosis develops when there is an absolute deficiency of
insulin and an increase in the insulin counter-regulatory hormones. Glucose
production by the liver increases, peripheral glucose use decreases, fat
mobilization increases, and ketogenesis (ketone formation) is stimulated.
Increased glucagon levels activate the gluconeogenic and ketogenic pathways
in the liver.
In the presence of insulin deficiency, hepatic overproduction of
beta-hydroxybutyrate and acetoacetic acids (ketone bodies) causes increased
ketone concentrations and an increased release of free fatty acids. As a
result of a loss of bicarbonate, which occurs when the ketone is formed,
bicarbonate buffering does not occur, and a metabolic acidosis occurs,
called DKA. Depression of the central nervous system from the accumulation
of ketones and resulting acidosis mat cause coma and death if left
untreated.
DKA may also occur in a person with diagnosed diabetes when energy
requirements increase during physical or emotional stress. Stress states
initiate the release of gluconeogenic hormones, resulting in the formation
of carbohydrates from protein or fat. The diabetic, who is sick, has an
infection, or who decreases or omits insulin doses is at a greatly increased
risk for developing diabetic ketoacidosis.
There are four main metabolic problems with diabetic ketoacidosis:
• Hyperosmalarity from hyperglycemia and dehydration.
• Metabolic acidosis from an accumulation of ketoacids.
• Extracellular volume depletion from osmotic diuresis.
• Electrolyte imbalances, such as loss of potassium and sodium, from osmotic
diuresis.
Manifestations of DKA result from severe dehydration and acidosis. These
signs and symptoms are summarized below. Laboratory tests will reveal the
following:
• Blood glucose levels higher than 250 mg/DL
• Plasma pH less than 7.3
• Plasma bicarbonate less than 15 mEq/L
• Presence of serum ketones
• Presence of urine ketones and glucose
• Abnormal levels of serum sodium, potassium, and chloride.
Signs and symptoms of Diabetic Ketoacidosis:
Dehydration from hyperglycemia:
• Thirst
• Warm, dry skin
• Soft eyeballs
• Dry mucous membranes
• Weakness
• Malaise
• Rapid, weak pulse
• Hypotension (low blood pressure)
Metabolic acidosis from ketosis:
• Nausea and vomiting
• Ketone breath (fruity, alcohol like)
• Lethargy
• Coma
Other signs and symptoms
• Abdominal pain
• Kussmaul's respirations (increased rate and depth of respirations, with
longer expiration; This is a response by the body to prevent a further
decrease in blood pH)
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