Classification of Diabetic Ketoacidosis (DKA) Severity
DKA is classified into three severity levels based primarily on arterial pH and serum bicarbonate levels: mild DKA (pH 7.25-7.30, bicarbonate 15-18 mEq/L), moderate DKA (pH 7.00-7.24, bicarbonate 10-15 mEq/L), and severe DKA (pH <7.00, bicarbonate <10 mEq/L). 1
Diagnostic Criteria for DKA Severity Classification
| Parameter | Mild DKA | Moderate DKA | Severe DKA |
|---|---|---|---|
| Plasma glucose | >250 mg/dL | >250 mg/dL | >250 mg/dL |
| Arterial pH | 7.25-7.30 | 7.00-7.24 | <7.00 |
| Serum bicarbonate | 15-18 mEq/L | 10 to <15 mEq/L | <10 mEq/L |
| Urine ketones | Positive | Positive | Positive |
| Serum ketones | Positive | Positive | Positive |
| Effective serum osmolality | Variable | Variable | Variable |
| Anion gap | >10 | >12 | >12 |
| Mental status | Alert | Alert/drowsy | Stupor/coma |
Clinical Implications of DKA Severity
The severity classification directly correlates with important clinical outcomes:
- Mortality risk: Increases with severity - moderate DKA has 13.3% mortality while severe DKA has 26% mortality 2
- ICU requirement: 6.7% for moderate DKA vs. 47.4% for severe DKA 2
- Ventilatory support: Invasive ventilation is typically only required in severe DKA (47% of cases) 2
- Hospital costs: Significantly higher for severe DKA (approximately double that of mild/moderate cases) 2
- Length of stay: Progressively longer with increasing severity 2
Management Considerations Based on Severity
Mild DKA
- Can often be managed with subcutaneous or intramuscular insulin
- Initial "priming" dose of regular insulin (0.4-0.6 units/kg body weight)
- Followed by 0.1 unit/kg/hour subcutaneously or intramuscularly 1
- May not require ICU admission
Moderate DKA
- Usually requires intravenous insulin therapy
- Approximately 6.7% require ICU care 2
- More frequent electrolyte monitoring
- Higher risk of complications than mild DKA
Severe DKA
- Requires ICU admission in nearly half of cases (47.4%) 2
- Continuous cardiac monitoring recommended
- May require central venous and arterial pressure monitoring
- Frequent blood chemistry determinations to guide therapy 1
- Higher risk of electrolyte abnormalities (hypokalemia, hypomagnesemia, hypophosphatemia) 3
- Increased risk of cerebral edema, particularly in pediatric patients
Monitoring Resolution of DKA
DKA resolution is defined by:
- Blood glucose <200 mg/dL
- Serum bicarbonate ≥18 mEq/L
- Venous pH >7.3 1
Important Caveats and Pitfalls
Ketone monitoring pitfall: The nitroprusside method only measures acetoacetic acid and acetone, not β-hydroxybutyrate (the predominant ketone body in DKA). During treatment, β-hydroxybutyrate converts to acetoacetic acid, potentially making ketosis appear worse when it's actually improving. Blood β-hydroxybutyrate measurement is preferred for monitoring. 1
Venous vs. arterial pH: Venous pH is typically only 0.03 units lower than arterial pH and can be used for monitoring after initial diagnosis, avoiding unnecessary arterial punctures. 1
Euglycemic DKA: Be aware that DKA can occur with blood glucose <250 mg/dL, particularly in patients on low-carbohydrate diets or SGLT2 inhibitors. This requires a modified treatment approach with earlier dextrose administration. 4
Type 2 diabetes: While more common in Type 1 diabetes, DKA can occur in Type 2 diabetes, especially in its severe form. 3
Common precipitating factors: Issues with insulin therapy and infections are the most frequent triggers across all severity levels. 3
By accurately classifying DKA severity at presentation, clinicians can better predict outcomes, determine appropriate level of care, and implement treatment protocols that match the patient's condition.