How do I diagnose euglycemic diabetic ketoacidosis versus classic diabetic ketoacidosis in a 78-year-old patient with type 1 diabetes presenting with chills and a stable glucose?

Diagnosing Euglycemic DKA versus Classic DKA

The key diagnostic difference is the glucose level: euglycemic DKA presents with blood glucose <250 mg/dL (often <200 mg/dL), while classic DKA presents with glucose >250 mg/dL, but both share the same metabolic acidosis criteria (pH <7.3, bicarbonate <18 mEq/L, and positive ketones). 1, 2

Diagnostic Criteria

Classic DKA 1, 2

• Plasma glucose: >250 mg/dL
• Arterial pH: <7.30 (mild: 7.25-7.30; moderate: 7.00-7.24; severe: <7.00)
• Serum bicarbonate: <18 mEq/L
• Positive ketones: in blood or urine
• Anion gap: >10

Euglycemic DKA 3, 4, 5

• Plasma glucose: <250 mg/dL (typically <200 mg/dL, sometimes even normal)
• Same metabolic acidosis: pH <7.30, bicarbonate <18 mEq/L
• Positive ketones: in blood or urine (β-hydroxybutyrate is preferred)
• Anion gap: >10

Critical Diagnostic Approach for Your 78-Year-Old Patient

Step 1: Obtain Initial Laboratory Panel

Draw immediately:

• Arterial or venous blood gas (venous pH acceptable, typically 0.03 lower than arterial) 2
• Serum electrolytes with calculated anion gap
• Serum β-hydroxybutyrate (preferred over nitroprusside method) 2
• Blood glucose (even if stable, document the actual value)
• BUN, creatinine (assess for acute kidney injury)
• Urinalysis for ketones and glucose

Step 2: Calculate Anion Gap

Anion gap = Na - (Cl + HCO3)

• Normal: 8-12 mEq/L
• DKA: typically >10-12 mEq/L

Step 3: Interpret Results Algorithmically

If pH <7.3 AND bicarbonate <18 mEq/L AND positive ketones:

• Glucose >250 mg/dL → Classic DKA 1, 2
• Glucose <250 mg/dL → Euglycemic DKA 3, 4, 5

Key Clinical Pitfalls in Your Patient

Why Euglycemic DKA is Easily Missed 3, 4, 6

1. Absence of hyperglycemia creates diagnostic confusion—clinicians may not consider DKA
2. Chills suggest infection, which is a common precipitant for both types 2
3. Type 1 diabetes patients can present with euglycemic DKA if they've taken insulin before arrival 7
4. Stable glucose doesn't exclude DKA—this is the hallmark of the euglycemic variant

Specific Risk Factors to Assess 3, 4, 5, 6

Ask about:

• SGLT-2 inhibitor use (empagliflozin, dapagliflozin, canagliflozin)—most common cause in type 2 diabetes
• Recent insulin administration (57% of euglycemic DKA cases) 7
• Poor oral intake with continued baseline insulin (29% of cases) 7
• Fasting state or prolonged decreased caloric intake
• Infection or acute illness (your patient has chills)
• Insulin pump malfunction (if applicable)

Physical Examination Findings

Look for these specific signs 1, 2:

• Kussmaul respirations (deep, labored breathing)—present in both types
• Dehydration: poor skin turgor, dry mucous membranes
• Tachycardia and hypotension
• Altered mental status (can range from alert to lethargic)
• Abdominal pain (25% have emesis, may be coffee-ground)
• Hypothermia or normothermia despite infection (hypothermia is a poor prognostic sign)

Distinguishing Features in Presentation

Euglycemic DKA Typically Shows 7:

• Milder acidosis on presentation (higher pH, higher bicarbonate, lower anion gap)
• Lower initial potassium (4.3 vs 5.3 mEq/L in classic DKA)
• Shorter time to resolution (13.5 vs 19.4 hours on insulin infusion)
• Higher risk of hypoglycemia during treatment (18.2% vs 4.8%)

Classic DKA Typically Shows 1, 2:

• Marked hyperglycemia (often >400-600 mg/dL)
• More severe dehydration from osmotic diuresis
• More pronounced electrolyte abnormalities
• Polyuria, polydipsia in the days preceding presentation

Monitoring β-Hydroxybutyrate

Measure serum β-hydroxybutyrate, not urine ketones by nitroprusside method 2. The nitroprusside method only detects acetoacetate and acetone, missing β-hydroxybutyrate (the predominant ketone in DKA). During treatment, β-hydroxybutyrate converts to acetoacetate, which can falsely suggest worsening ketosis if using nitroprusside testing.

Exclude Other Causes of High Anion Gap Metabolic Acidosis 6

Euglycemic DKA is a diagnosis of exclusion. Rule out:

• Lactic acidosis (sepsis, shock, metformin use)
• Uremic acidosis (renal failure)
• Toxic ingestions (methanol, ethylene glycol, salicylates)
• Alcoholic ketoacidosis (history of alcohol use, typically lower glucose)
• Starvation ketosis (milder acidosis, lower ketone levels)

Documentation for Diagnosis

Record these specific values:

• Exact glucose level (e.g., 185 mg/dL, not just "stable")
• Arterial or venous pH
• Serum bicarbonate
• Anion gap calculation
• Ketone measurement (preferably β-hydroxybutyrate level)
• Corrected sodium for hyperglycemia: add 1.6 mEq/L for every 100 mg/dL glucose above normal 2

Treatment Implications

For euglycemic DKA, immediately start glucose-containing IV fluids (D5W or D10W) along with insulin to prevent hypoglycemia 3, 5. Classic DKA protocols that delay dextrose until glucose <250 mg/dL will cause dangerous hypoglycemia in euglycemic DKA 7.

The diagnosis hinges on recognizing that ketoacidosis can occur without marked hyperglycemia—maintain high clinical suspicion in any diabetic patient with metabolic acidosis and ketones, regardless of glucose level 4, 6.