Diagnosis and Initial Treatment of Diabetic Ketoacidosis (DKA)
DKA is diagnosed by the biochemical triad of hyperglycemia (blood glucose >250 mg/dL), acidosis (pH <7.3, bicarbonate <15 mEq/L), and ketonemia, with specific measurement of β-hydroxybutyrate (bOHB) in blood being the preferred method for diagnosis and monitoring. 1
Diagnostic Criteria
DKA severity is classified based on the following parameters:
| 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 |
| Anion gap | >10 | >12 | >12 |
| Mental status | Alert | Alert/drowsy | Stupor/coma |
Essential Laboratory Tests 1
- Plasma glucose
- Blood urea nitrogen/creatinine
- Serum ketones (preferably β-hydroxybutyrate)
- Electrolytes
- Serum osmolality
- Arterial blood gases
- Complete blood count
- Urinalysis
Important Diagnostic Considerations
- β-hydroxybutyrate (bOHB) is the predominant ketone in DKA and should be specifically measured for diagnosis 2
- Nitroprusside-based ketone tests (dipsticks/tablets) only measure acetoacetate and acetone, not bOHB, making them inadequate for monitoring DKA treatment 2
- Euglycemic DKA can occur, particularly in patients using SGLT2 inhibitors, so hyperglycemia has been de-emphasized in recent guidelines 3, 4
- DKA must be differentiated from other causes of high anion gap metabolic acidosis (lactic acidosis, drug ingestions, renal failure) 2
Initial Treatment
1. Fluid Resuscitation (First Priority)
- Begin with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour initially 1
- Address severe dehydration and hypotension before insulin administration
- Improve tissue perfusion and renal function
- Adjust fluid choice based on hydration status and electrolytes after initial resuscitation
2. Insulin Therapy (Start 1-2 hours after fluid replacement)
- Continuous intravenous insulin infusion at 0.1 U/kg/hour 1
- Target glucose decrease: 50-75 mg/dL per hour
- Avoid initial insulin bolus in pediatric patients
- Continue IV insulin until resolution of DKA (bicarbonate ≥18 mEq/L, pH >7.3, anion gap normalized)
3. Electrolyte Replacement
- Potassium supplementation when levels are <5.5 mEq/L and renal function is adequate 1
- Add 20-30 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO₄)
- Consider phosphate replacement in patients with cardiac dysfunction, anemia, respiratory depression, or serum phosphate <1.0 mg/dL
4. Bicarbonate Therapy
- Not indicated in patients with pH >7.0
- May be considered if pH <6.9 1
5. Monitoring During Treatment
- Blood glucose: every 1-2 hours
- Electrolytes, BUN, creatinine: every 2-4 hours
- Venous pH and anion gap: every 2-4 hours
- Cardiac monitoring for T-wave changes (indicating hypo/hyperkalemia)
Resolution Criteria
DKA is considered resolved when:
- Blood glucose <200 mg/dL
- Serum bicarbonate ≥18 mEq/L
- Venous pH >7.3
- Anion gap normalized
- Patient is hemodynamically stable 1
Common Pitfalls and Caveats
Relying on nitroprusside-based ketone tests for monitoring: These tests don't measure bOHB and may show worsening (increasing acetoacetate) during successful treatment as bOHB converts to acetoacetate 2
Ignoring euglycemic DKA: Patients using SGLT2 inhibitors can develop DKA without significant hyperglycemia 2, 4
Delaying insulin therapy: While fluid resuscitation should come first, delaying insulin therapy beyond 1-2 hours can prolong acidosis 1
Inadequate monitoring: Frequent monitoring of glucose, electrolytes, and acid-base status is essential to detect complications early 1
Overlooking precipitating factors: Always identify and treat the underlying cause (infection, medication non-compliance, etc.) 3
By following these diagnostic criteria and treatment protocols, clinicians can effectively manage DKA and minimize associated morbidity and mortality.