Diagnosing Diabetic Ketoacidosis (DKA)
DKA is diagnosed when all three criteria are simultaneously present: hyperglycemia (plasma glucose >250 mg/dL), metabolic acidosis (arterial pH <7.3 AND serum bicarbonate <18 mEq/L), and positive ketones in blood or urine. 1, 2
Core Diagnostic Triad
All three of the following must be present simultaneously to confirm DKA:
- Hyperglycemia: Plasma glucose >250 mg/dL 1, 2
- Metabolic acidosis: Arterial pH <7.3 AND serum bicarbonate <18 mEq/L 1, 2
- Ketosis: Positive serum or urine ketones 1, 2
The diagnosis requires meeting all three criteria—not just one or two. 2
Essential Initial Laboratory Workup
When DKA is suspected, immediately obtain:
- Plasma glucose 1, 2
- Arterial blood gas (pH, bicarbonate) or venous pH 1, 2
- Serum electrolytes with calculated anion gap (anion gap >10 mEq/L supports DKA) 1, 2
- Blood β-hydroxybutyrate (preferred) or serum/urine ketones 2
- Blood urea nitrogen and creatinine 1, 2
- Serum osmolality 1, 2
- Complete blood count with differential 1, 2
- Urinalysis 1, 2
- Electrocardiogram 1, 2
Severity Stratification
DKA severity is classified based on degree of acidosis and mental status:
Mild DKA
- Plasma glucose >250 mg/dL 2
- Arterial pH 7.25–7.30 1, 2
- Serum bicarbonate 15–18 mEq/L 1, 2
- Anion gap >10 mEq/L 1, 2
- Mental status: Alert 1, 2
Moderate DKA
- Plasma glucose >250 mg/dL 2
- Arterial pH 7.00–7.24 1, 2
- Serum bicarbonate 10 to <15 mEq/L 1, 2
- Anion gap >12 mEq/L 1, 2
- Mental status: Alert/drowsy 1, 2
Severe DKA
- Plasma glucose >250 mg/dL 2
- Arterial pH <7.00 1, 2
- Serum bicarbonate <10 mEq/L 1, 2
- Anion gap >12 mEq/L 1, 2
- Mental status: Stupor/coma 1, 2
Critical Ketone Measurement Considerations
Measure blood β-hydroxybutyrate (β-OHB) specifically for diagnosing DKA, as this is the preferred method recommended by the American Diabetes Association. 2
Why β-OHB is Superior
- Nitroprusside-based tests (urine dipsticks, serum tablets) only detect acetoacetate and acetone, NOT β-hydroxybutyrate, which is the predominant ketone in DKA 2, 3
- During treatment, β-OHB converts to acetoacetate, making nitroprusside tests falsely suggest worsening ketosis when the patient is actually improving 2, 3
- Blood β-OHB measurement accurately reflects the patient's ketone body levels for both diagnosis and monitoring treatment response 2
Euglycemic DKA: A Critical Diagnostic Pitfall
Approximately 10% of all DKA presentations are euglycemic, defined by plasma glucose <200 mg/dL despite meeting the other DKA criteria. 2
Diagnostic Criteria for Euglycemic DKA
- Blood glucose <200–250 mg/dL 2
- Metabolic acidosis still present (pH <7.3, bicarbonate <18 mEq/L) 2
- Elevated β-hydroxybutyrate and anion gap 2
- Either documented hyperglycemia at any point or a prior history of diabetes 2
Common Precipitating Factors for Euglycemic DKA
- SGLT2 inhibitor use (most frequent modern cause and significantly increases DKA risk) 2, 4, 5
- Reduced caloric intake or prolonged fasting 2, 5, 6
- Pregnancy 2, 5
- Heavy alcohol consumption 2, 5
- Chronic liver disease 2, 5
- Cocaine abuse 2
If you only consider the serum glucose level while ignoring the biochemical profile and failing to obtain ketone levels, the diagnosis will be missed. 6
Differential Diagnosis
DKA must be distinguished from other causes of high anion gap metabolic acidosis:
Alcoholic Ketoacidosis (AKA)
- Clinical history of alcohol use 2
- Glucose typically normal to mildly elevated (rarely >250 mg/dL) or hypoglycemic 2
- Often presents with profoundly low bicarbonate levels (often <18 mEq/L) 3
Starvation Ketosis
- Serum bicarbonate typically not lower than 18 mEq/L 1, 2, 3
- Less severe acidosis than DKA 2
- Clinical history of prolonged fasting 2
Other High Anion Gap Causes
- Lactic acidosis 1
- Toxic ingestions (salicylate, methanol, ethylene glycol, paraldehyde) 1
- Chronic renal failure (more typically hyperchloremic acidosis) 1
Resolution Criteria
DKA is considered resolved when all of the following are met: