What are the criteria for diagnosing diabetic ketoacidosis (DKA)?

Diagnostic Criteria for Diabetic Ketoacidosis (DKA)

DKA is diagnosed when blood glucose is >250 mg/dL (or prior diabetes history), venous pH <7.3, serum bicarbonate <15 mEq/L, and moderate ketonuria or ketonemia are all present together. 1

Core Diagnostic Triad

The American Diabetes Association defines DKA by three simultaneous criteria 1:

• Hyperglycemia: Blood glucose >250 mg/dL 1
• Metabolic acidosis: Venous pH <7.3 AND serum bicarbonate <15 mEq/L 1
• Ketosis: Moderate ketonuria or ketonemia (preferably measured as β-hydroxybutyrate in blood) 1

Important caveat: Approximately 10% of DKA cases present as euglycemic DKA with glucose <200 mg/dL, particularly in patients on SGLT2 inhibitors, pregnant patients, those with reduced food intake, or chronic alcohol use. 2 In these cases, the diagnosis still requires pH <7.3, bicarbonate <15 mEq/L, and elevated ketones despite "normal" glucose. 2

Severity Classification

DKA severity is stratified based on pH and bicarbonate levels 1:

• Mild DKA: Venous pH 7.25-7.30, bicarbonate 15-18 mEq/L, alert mental status 1
• Moderate DKA: Venous pH 7.00-7.24, bicarbonate 10-15 mEq/L, drowsy mental status 1
• Severe DKA: Venous pH <7.00, bicarbonate <10 mEq/L, associated with higher morbidity and mortality requiring intensive monitoring 1

Essential Laboratory Workup

Upon presentation with suspected DKA, immediately obtain 1:

• Complete metabolic panel (electrolytes, BUN, creatinine)
• Venous blood gas (arterial not necessary for initial diagnosis)
• Complete blood count
• Urinalysis
• Serum β-hydroxybutyrate (preferred over urine ketones)
• Calculate anion gap: [Na⁺] - ([Cl⁻] + [HCO₃⁻]), which should be >10-12 mEq/L 1
• Correct sodium for hyperglycemia: [measured Na] + [(glucose - 100)/100] × 1.6 1

If infection is suspected, obtain bacterial cultures of urine, blood, and throat. 1

Critical Pitfall: Ketone Measurement

Never rely on urine ketones or nitroprusside-based tests for diagnosis or monitoring. 1 These methods only detect acetoacetate and acetone, completely missing β-hydroxybutyrate—the predominant ketoacid in DKA. 1 During treatment, β-hydroxybutyrate converts to acetoacetate, paradoxically making nitroprusside tests appear worse even as the patient improves. 1 Direct blood β-hydroxybutyrate measurement is the gold standard. 1

Resolution Criteria

DKA is considered resolved when all of the following are met 3:

• Glucose <200 mg/dL 3
• Serum bicarbonate ≥18 mEq/L 3
• Venous pH >7.3 3
• Anion gap ≤12 mEq/L 3

Do not stop insulin therapy based on glucose normalization alone—ketoacidosis typically takes longer to clear than hyperglycemia. 2 Continue insulin infusion until all resolution criteria are met, adding dextrose to IV fluids when glucose falls below 250 mg/dL to prevent hypoglycemia while clearing ketones. 1

Special Populations at Risk

Risk factors for euglycemic DKA include 2:

• SGLT2 inhibitor use (0.6-4.9 events per 1,000 patient-years) 2
• Pregnancy (up to 2% of pregestational diabetes pregnancies) 2
• Reduced food intake/starvation 2
• Chronic alcohol use 2
• Chronic liver disease 2

Patients with type 1 diabetes, younger age, prior DKA history, high A1C, very-low-carbohydrate diets, prolonged fasting, or missed insulin doses are at highest risk. 2