How to Determine if a Patient is in Diabetic Ketoacidosis (DKA)
DKA is diagnosed when all three components of the diagnostic triad are present: hyperglycemia (traditionally >250 mg/dL, though euglycemic DKA exists), metabolic acidosis (pH <7.3, bicarbonate <18 mEq/L, anion gap >10 mEq/L), and elevated ketones in blood or urine. 1, 2, 3
Essential Diagnostic Criteria
The diagnosis requires all three of the following components—the 'D', 'K', and 'A': 3, 4
- 'D' (Diabetes/Hyperglycemia): Blood glucose >250 mg/dL OR a known history of diabetes mellitus 1, 3
- 'K' (Ketones): Positive serum ketones (preferred) or urine ketones 1, 2
- 'A' (Acidosis): High anion gap metabolic acidosis with arterial pH <7.3, serum bicarbonate <18 mEq/L, and anion gap >10 mEq/L 1, 2
Severity Classification
DKA severity is stratified based on acidosis severity: 1
- Mild DKA: pH 7.25-7.30, bicarbonate 15-18 mEq/L, patient alert
- Moderate DKA: pH 7.00-7.24, bicarbonate 10-15 mEq/L, patient alert or drowsy
- Severe DKA: pH <7.00, bicarbonate <10 mEq/L, patient stuporous or comatose
Clinical Presentation
Key Symptoms to Assess
- Most common: Polyuria and polydipsia 2
- Gastrointestinal: Nausea, vomiting, abdominal pain 1, 2
- Constitutional: Weight loss, severe fatigue, dyspnea 2
- Preceding illness: Febrile illness or infection 1, 2
Physical Examination Findings
- Mental status: Ranges from full alertness to profound lethargy or coma (coma more common in hyperosmolar hyperglycemic state) 1
- Temperature: Patients can be normothermic or hypothermic despite infection; hypothermia is a poor prognostic sign 1
- Dehydration signs: Assess volume status and perfusion 1
Critical Laboratory Evaluation
Initial Essential Tests
Obtain the following immediately: 1, 2
- Plasma glucose
- Arterial blood gas (pH and bicarbonate)
- Serum electrolytes with calculated anion gap
- Serum ketones (β-hydroxybutyrate preferred over nitroprusside method)
- Blood urea nitrogen and creatinine
- Serum osmolality
- Urinalysis with urine ketones
- Complete blood count with differential
- Electrocardiogram
Additional Tests to Consider
- Infection workup: Blood cultures, urine cultures, throat cultures if infection suspected 1
- Cardiac markers: Troponin, creatine kinase 2
- Pancreatic enzymes: Amylase, lipase 2
- Hepatic function: Transaminases 2
- Hemoglobin A1C 2
- Chest radiography 2
Important Diagnostic Pitfalls
Euglycemic DKA
Hyperglycemia has been de-emphasized in recent guidelines due to increasing incidence of euglycemic DKA (glucose <250 mg/dL). 2, 5
- Risk factors: SGLT2 inhibitor use, insulin administration prior to arrival, poor oral intake with baseline insulin use 5
- Presentation: Milder acidosis on presentation (higher pH and bicarbonate, lower anion gap) but still meets criteria for metabolic acidosis and ketosis 5
- Clinical significance: Can be easily missed if relying solely on hyperglycemia for diagnosis 2, 5
Ketone Measurement Method
- β-hydroxybutyrate measurement is preferred over nitroprusside method 1
- Nitroprusside method only measures acetoacetic acid and acetone, not β-hydroxybutyrate (the most prevalent acid in DKA) 1
- During treatment, β-hydroxybutyrate converts to acetoacetic acid, which may falsely suggest worsening ketosis when using nitroprusside method 1
Vital Sign Triage
Patients with glucose ≤400 mg/dL AND normal vital signs (systolic BP ≥100 mmHg, pulse ≤90/min, respiratory rate ≤20/min) have very low risk for DKA and can be initially triaged as low risk. 6