Diabetic Ketoacidosis: Clinical Presentation and Diagnostic Criteria
Diabetic ketoacidosis (DKA) is diagnosed by the triad of hyperglycemia (blood glucose ≥250 mg/dL), metabolic acidosis (pH <7.3, bicarbonate <18 mEq/L, anion gap >10 mEq/L), and positive serum or urine ketones 1.
Clinical Presentation
Symptom Timeline and Evolution
DKA typically evolves rapidly, with metabolic alterations developing within 24 hours, though some patients present acutely without preceding symptoms 1. This contrasts sharply with hyperosmolar hyperglycemic state, which develops over days to weeks.
Classic Symptoms (in order of frequency)
- Polyuria and polydipsia (98% of cases) 2
- Weight loss (81%)
- Fatigue (62%)
- Dyspnea (57%)
- Vomiting (46%)
- Preceding febrile illness (40%)
- Abdominal pain (32%) - unique to DKA, not seen in HHS 1
- Polyphagia (23%)
Physical Examination Findings
- Kussmaul respirations (deep, rapid breathing) - pathognomonic for DKA 1
- Poor skin turgor (dehydration)
- Tachycardia
- Hypotension
- Altered mental status ranging from full alertness to stupor/coma
- Coffee-ground emesis (25% of patients) - related to hemorrhagic gastritis 1
Critical pitfall: Patients may be normothermic or hypothermic despite infection being the precipitating factor, due to peripheral vasodilation. Hypothermia is a poor prognostic sign 1.
Diagnostic Criteria
Laboratory Thresholds by Severity 1
Mild DKA:
- Glucose ≥250 mg/dL
- pH 7.25-7.30
- Bicarbonate 15-18 mEq/L
- Positive ketones
- Patient alert
Moderate DKA:
- Glucose ≥250 mg/dL
- pH 7.00-7.24
- Bicarbonate 10-15 mEq/L
- Positive ketones
- Alert/drowsy
Severe DKA:
- Glucose ≥250 mg/dL
- pH <7.00
- Bicarbonate <10 mEq/L
- Positive ketones
- Stupor/coma
Essential Initial Laboratory Workup 1
After history and physical examination, obtain immediately:
- Plasma glucose
- Arterial blood gases (or venous pH - acceptable alternative)
- Serum electrolytes with calculated anion gap [(Na) - (Cl + HCO3)]
- Serum ketones (β-hydroxybutyrate preferred over nitroprusside method)
- Blood urea nitrogen and creatinine
- Serum osmolality [2(measured Na) + glucose/18]
- Urinalysis with urine ketones
- Complete blood count with differential
- Electrocardiogram
Important Diagnostic Nuances
β-hydroxybutyrate measurement is superior to the traditional nitroprusside method, which only detects acetoacetate and acetone but misses β-hydroxybutyrate - the predominant and strongest acid in DKA 1. During treatment, β-hydroxybutyrate converts to acetoacetate, potentially making ketosis appear worse by nitroprusside testing when it's actually improving.
Euglycemic DKA is increasingly recognized, particularly with SGLT-2 inhibitor use 3. Recent guidelines have de-emphasized the hyperglycemia threshold because DKA can occur with normal or minimally elevated glucose levels.
Differential Diagnosis Considerations 1
Not all ketoacidosis is DKA:
- Starvation ketosis: Bicarbonate usually ≥18 mEq/L, glucose normal to mildly elevated
- Alcoholic ketoacidosis: Glucose ranges from mildly elevated (rarely >250 mg/dL) to hypoglycemic
- Both distinguished by clinical history and glucose levels
Precipitating Factors to Identify
Infection is the most common trigger 1. Other precipitating factors include:
- New-onset type 1 diabetes or insulin discontinuation/inadequacy
- Myocardial infarction
- Cerebrovascular accident
- Pancreatitis
- Trauma
- Drugs: corticosteroids, thiazides, sympathomimetics (dobutamine, terbutaline), SGLT-2 inhibitors 3
- Alcohol abuse
Obtain cultures (blood, urine, throat) and initiate appropriate antibiotics if infection is suspected 1.
Additional Workup Based on Clinical Context 3
Consider:
- Amylase and lipase (pancreatitis)
- Hepatic transaminases
- Troponin (myocardial infarction)
- Creatine kinase
- Chest radiography
- A1C level
Key Clinical Pearls
One-third of DKA cases occur in patients without known diabetes 2, making DKA a common presentation of new-onset diabetes, particularly in children.
Mental status varies widely - from completely alert to comatose. Coma is more frequent in hyperosmolar hyperglycemic state than DKA 1.
Mortality rates: DKA carries 1-5% mortality in experienced centers 1, 2, with worse prognosis at extremes of age and with coma, hypotension, or hypothermia 1.