Diagnostic Criteria for Diabetic Ketoacidosis (DKA)
The diagnosis of DKA requires the presence of hyperglycemia (blood glucose >250 mg/dL), acidosis (pH <7.3 or bicarbonate <15 mEq/L), and ketonemia. 1
Essential Diagnostic Criteria
- Blood glucose >250 mg/dL (although euglycemic DKA can occur with glucose <250 mg/dL, especially with SGLT2 inhibitor use) 1, 2
- Acidosis: pH <7.3 or bicarbonate <15 mEq/L 1
- Presence of ketones in serum or urine 1
- Anion gap >10 mEq/L (typically elevated) 2
Laboratory Evaluation
Required Tests
- Plasma glucose
- Arterial or venous blood gases (pH, bicarbonate)
- Serum ketones (preferred over urine ketones)
- Electrolytes (to calculate anion gap)
- Blood urea nitrogen/creatinine
- Complete blood count
- Urinalysis
Additional Tests to Consider
- A1C (to differentiate new-onset from established diabetes)
- Osmolality
- Electrocardiogram
- Amylase, lipase, hepatic transaminases (to identify precipitating causes)
- Blood and urine cultures (if infection suspected)
- Chest radiography (if respiratory symptoms present) 2
Severity Assessment
DKA severity can be classified based on the degree of acidosis:
- Mild: pH 7.25-7.3 or bicarbonate 15-18 mEq/L
- Moderate: pH 7.0-7.24 or bicarbonate 10-14.9 mEq/L
- Severe: pH <7.0 or bicarbonate <10 mEq/L 3
Clinical Presentation
Common symptoms and signs include:
- Polyuria and polydipsia (98%)
- Weight loss (81%)
- Fatigue (62%)
- Dyspnea (57%)
- Nausea and vomiting (46%)
- Preceding febrile illness (40%)
- Abdominal pain (32%)
- Polyphagia (23%)
- Altered mental status (varies with severity) 3, 2
Differential Diagnosis
DKA must be differentiated from:
- Hyperosmolar hyperglycemic state (HHS)
- Starvation ketosis
- Alcoholic ketoacidosis
- Lactic acidosis
- Other causes of high anion gap metabolic acidosis 2
Special Considerations
Euglycemic DKA
- Defined as DKA with serum glucose <250 mg/dL
- Associated with SGLT2 inhibitors, pregnancy, reduced food intake, alcohol use, and chronic liver disease
- Requires the same diagnostic criteria except for the glucose threshold 4, 2
Resolution Criteria
DKA is considered resolved when:
- Blood glucose <200 mg/dL
- Serum bicarbonate ≥18 mEq/L
- Venous pH >7.3
- Anion gap normalized 1
Pitfalls to Avoid
Missing euglycemic DKA: Don't rule out DKA solely based on glucose <250 mg/dL, especially in patients taking SGLT2 inhibitors 4, 2
Inadequate monitoring: Regular assessment of electrolytes, especially potassium, is crucial as hypokalemia can lead to fatal arrhythmias during treatment 1, 5
Overlooking precipitating factors: Always identify and treat the underlying cause (infection, medication non-compliance, new-onset diabetes) 1
Delayed diagnosis in type 2 diabetes: DKA can occur in type 2 diabetes and may be severe (pH ≤6.9) 6
Failure to recognize cerebral edema: This is a rare but potentially fatal complication, especially in pediatric patients 1, 3