Criteria for Mild vs Moderate vs Severe Diabetic Ketoacidosis (DKA)
The American Diabetes Association classifies DKA severity based primarily on arterial pH, serum bicarbonate levels, and mental status, with mild DKA defined as pH 7.25-7.30 and bicarbonate 15-18 mEq/L, moderate DKA as pH 7.00-7.24 and bicarbonate 10-15 mEq/L, and severe DKA as pH <7.00 and bicarbonate <10 mEq/L. 1, 2
Diagnostic Criteria for DKA
All forms of DKA require the following basic diagnostic criteria:
- Blood glucose >250 mg/dL (though euglycemic DKA can occur with glucose <250 mg/dL) 2, 3
- Presence of ketones in blood or urine 2
- Metabolic acidosis with increased anion gap 1, 2
Severity Classification Parameters
Mild DKA
- Arterial pH: 7.25-7.30 1, 2
- Serum bicarbonate: 15-18 mEq/L 1, 2
- Anion gap: >10 mEq/L 1
- Mental status: Alert 1, 2
Moderate DKA
- Arterial pH: 7.00-7.24 1, 2
- Serum bicarbonate: 10 to <15 mEq/L 1, 2
- Anion gap: >12 mEq/L 1
- Mental status: Alert/drowsy 1, 2
Severe DKA
- Arterial pH: <7.00 1, 2
- Serum bicarbonate: <10 mEq/L 1, 2
- Anion gap: >12 mEq/L 1
- Mental status: Stupor/coma 1
Laboratory Evaluation
A comprehensive laboratory assessment is essential for accurate classification:
- Complete metabolic panel 2
- Venous blood gases (typically 0.03 units lower than arterial pH) 2, 4
- Serum ketones (preferably β-hydroxybutyrate) 2, 4
- Calculation of anion gap: [Na⁺] - ([Cl⁻] + [HCO₃⁻]) 2
- Corrected sodium for hyperglycemia: [measured Na (mEq/L)] + [glucose (mg/dL) - 100]/100 × 1.6 2
Clinical Considerations
- Severe DKA is associated with more frequent electrolyte abnormalities (hypokalemia, hypomagnesemia, hypophosphatemia) 5
- Mental status alterations correlate with severity - alert in mild cases, drowsy in moderate cases, and stupor/coma in severe cases 1, 2
- Patients with severe DKA more frequently require ICU admission (80.8% in one study) 5
- Type 2 diabetes patients can develop severe DKA, contrary to common belief 6, 5
Important Variants and Pitfalls
- Euglycemic DKA: Presents with normal or near-normal blood glucose (<250 mg/dL) but still has ketoacidosis requiring insulin therapy 3
- Diabetic ketoalkalosis: A variant where mixed acid-base disorders result in pH >7.4 despite significant ketosis 7
- Relying solely on urine ketones is not recommended as the nitroprusside method doesn't measure β-hydroxybutyrate, the predominant ketone body in DKA 2, 4
- Resolution criteria for DKA include: glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, venous pH >7.3, and anion gap ≤12 mEq/L 4
Monitoring During Treatment
- Blood should be drawn every 2-4 hours to measure electrolytes, glucose, BUN, creatinine, osmolality, and venous pH 2, 4
- Venous pH and anion gap should be followed to monitor resolution of acidosis 4
- Ketonemia typically takes longer to clear than hyperglycemia, requiring continued insulin therapy even after glucose normalizes 2, 4