Three Classic Signs of Diabetic Ketoacidosis
The three classic signs of DKA are hyperglycemia (blood glucose >250 mg/dL), metabolic acidosis (pH <7.3, serum bicarbonate <18 mEq/L), and elevated ketones in blood or urine. 1
The Diagnostic Triad
The American Diabetes Association defines DKA by three essential criteria that must all be present:
- Hyperglycemia: Blood glucose typically >250 mg/dL (though euglycemic DKA with glucose <250 mg/dL can occur, particularly with SGLT2 inhibitor use) 1, 2
- Metabolic acidosis: Arterial pH <7.3 and serum bicarbonate <18 mEq/L, with an elevated anion gap >10-12 mEq/L 1, 2
- Elevated ketones: Positive ketones in serum or urine, with β-hydroxybutyrate being the predominant ketone body 1, 3
Clinical Presentation Context
While the biochemical triad confirms diagnosis, patients typically present with characteristic symptoms that evolve rapidly (usually <24 hours):
- Classic hyperglycemic symptoms: Polyuria, polydipsia, and weight loss are the hallmark presenting features 4, 5, 2
- Kussmaul respirations: Deep, labored breathing pattern indicating severe metabolic acidosis as the body attempts respiratory compensation 1, 5, 6
- Dehydration signs: Poor skin turgor, tachycardia, and hypotension from osmotic diuresis and volume depletion 1, 5
Important Clinical Caveats
Recent guidelines have de-emphasized the absolute requirement for hyperglycemia >250 mg/dL because euglycemic DKA is increasingly recognized, particularly in patients taking SGLT2 inhibitors, during pregnancy, or with reduced caloric intake. 1, 2 In these cases, severe metabolic acidosis and elevated ketones may be present despite glucose levels of 177-180 mg/dL or lower. 7
The diagnosis should never rely on urine ketone testing alone, as nitroprusside-based tests do not measure β-hydroxybutyrate (the predominant ketone in DKA) and can remain falsely positive during treatment. 1 Serum β-hydroxybutyrate measurement is preferred for both diagnosis and monitoring treatment response. 1
Altered mental status (ranging from alert to coma) and gastrointestinal symptoms (nausea, vomiting, abdominal pain) are common but not part of the diagnostic triad. 1, 5, 3