Pathophysiology of Euglycemic Ketoacidosis
Euglycemic ketoacidosis occurs when insulin deficiency or resistance triggers ketone body production despite relatively normal blood glucose levels (typically <200-250 mg/dL), resulting from a combination of reduced insulin-to-glucagon ratio, enhanced urinary glucose excretion, and inadequate carbohydrate availability.
Core Metabolic Mechanisms
The fundamental pathophysiology mirrors traditional diabetic ketoacidosis but with a critical distinction: glucose levels remain deceptively low while severe ketoacidosis develops 1. The process involves:
Hormonal Dysregulation
- Reduced insulin-to-glucagon ratio signals cellular fuel deprivation, even when absolute insulin levels aren't profoundly deficient 2
- Elevated counterregulatory hormones (glucagon, catecholamines, cortisol, growth hormone) drive the catabolic state 1
- This hormonal milieu promotes lipolysis from adipose tissue, releasing free fatty acids into circulation 1
Ketone Body Production
- Free fatty acids undergo unrestrained hepatic β-oxidation, producing acetyl-CoA 2
- Acetyl-CoA converts to ketone bodies: β-hydroxybutyrate, acetoacetate, and acetone 1, 2
- These ketoacids accumulate, causing high anion gap metabolic acidosis 3
Why Glucose Remains "Normal"
The euglycemic presentation results from several concurrent mechanisms:
SGLT2 Inhibitor-Mediated Mechanisms (Most Common Modern Cause)
SGLT2 inhibitors fundamentally alter the pathophysiology by eliminating 60-100 grams of glucose daily through urinary excretion 4. This creates a unique metabolic environment:
- Enhanced glycosuria prevents hyperglycemia accumulation despite ongoing gluconeogenesis 4
- Increased lipolysis occurs as the body compensates for urinary glucose losses 4
- Hyperglucagonemia drives gluconeogenesis while glucose is simultaneously excreted 4
- Decreased urinary ketone excretion allows ketone body accumulation 4
Non-SGLT2 Inhibitor Mechanisms
In other clinical scenarios, euglycemia results from:
- Carbohydrate deficit states: starvation, ketogenic diets, pregnancy, chronic liver disease 5, 3, 6
- Preserved residual insulin: enough to suppress hepatic glucose production but insufficient to prevent lipolysis 1, 5
- Ongoing glucose utilization: peripheral tissues continue consuming glucose while ketogenesis proceeds unchecked 6
Clinical Context and Risk Factors
SGLT2 Inhibitor-Associated euDKA
Risk factors include 4:
- Insulin deficiency (missed doses, pump failure)
- Metabolic stressors (surgery, trauma, infection, prolonged fasting)
- Very low-carbohydrate/ketogenic diets (carbohydrate intake less than daily urinary glucose losses)
- Alcohol abuse
- Volume depletion
Critical timing consideration: euDKA can occur within 48-72 hours of SGLT2 inhibitor initiation when combined with acute stressors like infection and dietary carbohydrate restriction 7.
Non-SGLT2 Inhibitor Causes
- Pregnancy-associated: triggered by starvation or illness in metabolically vulnerable state 2
- Alcoholic ketoacidosis: alcohol metabolism combined with reduced food intake 2, 5
- Post-bariatric surgery: reduced carbohydrate absorption creates chronic substrate deficit 3, 8
- Chronic liver disease/glycogen storage diseases: impaired gluconeogenesis 5, 3
Distinguishing Features from Classic DKA
The pathophysiology differs from traditional DKA in critical ways:
- Milder insulin deficiency: relative rather than absolute insulin lack 3
- Preserved C-peptide: often detectable, indicating some endogenous insulin production 7
- Lower insulin requirements: treatment typically requires minimal insulin (10-15 units total) compared to classic DKA 7
- Rapid onset possible: can develop within days rather than the typical gradual evolution 9
Diagnostic Pitfall
The absence of marked hyperglycemia creates a dangerous diagnostic delay 5, 3. Clinicians expecting glucose >250 mg/dL may miss the diagnosis entirely, focusing instead on other causes of high anion gap metabolic acidosis. This delay worsens outcomes and mortality 3.
The key is recognizing that severe metabolic acidosis (pH <7.3), elevated ketones (β-hydroxybutyrate >3 mmol/L), and high anion gap can occur with glucose <200 mg/dL 3, 6. Always check serum ketones in diabetic patients presenting with acidosis, regardless of glucose level.
Emerging Considerations
Recent evidence suggests dual GLP-1/GIP receptor agonists (tirzepatide) may also precipitate euglycemic ketoacidosis, particularly post-bariatric surgery 8. The mechanism likely involves profound appetite suppression leading to severe carbohydrate restriction combined with altered incretin physiology.
Additionally, concurrent medications like acetazolamide can create mixed acid-base disorders, combining ketoacid accumulation with renal bicarbonate wasting, resulting in exceptionally severe acidosis 10.