Diagnosing Diabetic Ketoacidosis (DKA)

Core Diagnostic Criteria

The American Diabetes Association establishes that all three components must be present simultaneously for DKA diagnosis, including blood glucose >250 mg/dL, venous pH <7.3, and serum bicarbonate <15 mEq/L, with elevated blood ketones, preferably measured as β-hydroxybutyrate 1, 2
Blood glucose >250 mg/dL is a key criterion, though this threshold has been de-emphasized in recent guidelines due to increasing incidence of euglycemic DKA, particularly in patients on SGLT2 inhibitors 2
Venous pH <7.3 reflects the severity of ketoacidosis and is required for diagnosis 1, 2
Serum bicarbonate <15 mEq/L indicates metabolic acidosis 1, 2
Elevated blood β-hydroxybutyrate (β-OHB) is the preferred ketone measurement 1, 2

A complete metabolic panel, including sodium, potassium, chloride, bicarbonate, BUN, creatinine, and glucose, should be obtained immediately upon presentation 1
Venous blood gas, including pH, pCO2, and bicarbonate, is essential for diagnosis 1
Blood β-hydroxybutyrate measurement is the gold standard, not urine ketones or nitroprusside-based tests 2
A complete blood count with differential, urinalysis, serum osmolality, and electrocardiogram should also be performed 2
Anion gap calculation, [Na⁺] - ([Cl⁻] + [HCO₃⁻]), should be >10-12 mEq/L in DKA 1, 2

DKA severity determines monitoring intensity and prognosis, with mild, moderate, and severe classifications based on pH, bicarbonate, anion gap, and mental status 3, 1
Mild DKA is characterized by pH 7.25-7.30, bicarbonate 15-18 mEq/L, anion gap >10, and alert mental status 3, 1
Moderate DKA is characterized by pH 7.00-7.24, bicarbonate 10-15 mEq/L, anion gap >12, and drowsy/lethargic mental status 3, 1
Severe DKA is characterized by pH <7.00, bicarbonate <10 mEq/L, anion gap >12, and stuporous or comatose mental status, with higher morbidity and mortality 3, 1

DKA must be distinguished from other causes of high anion gap metabolic acidosis, including lactic acidosis, toxic ingestions, chronic renal failure, and metformin use 3, 4, 1, 2
Lactic acidosis can be diagnosed by measuring blood lactate 2
Toxic ingestions, such as salicylate, methanol, and ethylene glycol, can be identified by specific laboratory tests and clinical presentation 1

The classical presentation of DKA includes history of polyuria, polydipsia, weight loss, vomiting, abdominal pain, weakness, and altered mental status, as well as physical findings of poor skin turgor, Kussmaul respirations, tachycardia, hypotension, fruity breath odor, and altered mental status 3, 4
Up to 25% of patients may have coffee-ground emesis due to hemorrhagic gastritis 3

Blood should be drawn every 2-4 hours to measure electrolytes, glucose, venous pH, β-hydroxybutyrate, anion gap, BUN, creatinine, and serum osmolality 1, 2

DKA is resolved when all of the following are met: glucose <200 mg/dL, venous pH >7.3, serum bicarbonate ≥18 mEq/L, and anion gap ≤12 mEq/L 1, 2
Ketonemia typically takes longer to clear than hyperglycemia, requiring continued monitoring and insulin therapy even after glucose normalizes 1