Study Note: Diabetic Ketoacidosis (DKA) Oct 14th 2025

Overview:

Diabetic ketoacidosis (DKA) is a serious, potentially life-threatening complication of diabetes mellitus. It leads to about 135,000 hospital admissions per year in the U.S., costing around $2.4 billion annually. Understanding its pathophysiology and treatment is crucial.

Pathophysiology at the Cellular Level

Normal Physiology:

• Insulin binds to its receptor on the cell membrane, allowing glucose to enter the cell.

• Inside the cell, glucose undergoes glycolysis → pyruvate → acetyl-CoA → Krebs cycle → ATP production.

• Insulin also inhibits fatty acid oxidation, preventing excessive ketone body formation.

In DKA (low or no insulin):

• Glucose cannot enter the cell, so glycolysis and ATP production from glucose stop.

• Fatty acid oxidation is disinhibited, causing fatty acids to flood into mitochondria.

• Through β-oxidation, fatty acids are broken into 2-carbon units (acetyl-CoA).

• Excess acetyl-CoA leads to production of ketone bodies:

  • Acetone (volatile → fruity breath odor)

  • Acetoacetate

  • β-hydroxybutyrate

• These ketone bodies are acidic, contributing to metabolic acidosis.

Biochemical Consequences

1. Low Insulin → Increased Lipolysis → Ketone Bodies → Metabolic Acidosis

   • Ketone bodies release protons (H⁺), causing anion gap metabolic acidosis.

   • The anion gap = Na⁺ - (Cl⁻ + HCO₃⁻).
     A gap >12 indicates unmeasured anions (like ketones).

2. Potassium Shifts:

   • Increased serum H⁺ drives H⁺ into cells and K⁺ out → Hyperkalemia (initially).

   • Despite high serum K⁺, total body potassium is depleted due to urinary loss and intracellular shift reversal after treatment.

3. Hyperglycemia → Osmotic Diuresis → Dehydration

   • Excess glucose exceeds renal reabsorption capacity → glucose in urine (glycosuria).

   • Water follows glucose → polyuria, dehydration, hypotension, tachycardia.

   • Leads to increased creatinine (due to decreased renal perfusion).

4. Electrolyte Loss:

   • Loss of potassium and phosphate in urine → total body depletion.

Key Findings in DKA

• High blood glucose

• Anion gap metabolic acidosis

• Elevated serum ketones (especially β-hydroxybutyrate)

• Dehydration

• Possible high serum K⁺ but low total body K⁺

• Low or normal phosphate

• Increased creatinine due to dehydration

Summary of Mechanisms

Problem	Mechanism	Effect
↓ Insulin	Glucose unable to enter cells	↑ Blood glucose
↓ Insulin inhibition	↑ Fatty acid transport into mitochondria	↑ Ketone bodies
↑ Ketones	Acid release (H⁺)	Anion gap metabolic acidosis
↑ H⁺ in blood	H⁺/K⁺ exchange	↑ Serum K⁺ (initially)
↑ Glucose	Osmotic diuresis	Dehydration, ↑ creatinine
Fluid loss	Renal K⁺ & phosphate loss	Total body depletion

In Summary:

DKA is characterized by:

• Ketone body production

• Hyperglycemia

• Metabolic acidosis (anion gap type)

• Dehydration

• Electrolyte loss (especially K⁺ and phosphate)

Treatment (covered in next section) focuses on:

1. Fluid replacement

2. Insulin therapy

3. Electrolyte correction (especially K⁺)

4. Addressing underlying cause (e.g., infection, missed insulin dose)