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)