Recognizing Diabetic Ketoacidosis (DKA)
You will know a patient is in DKA when they present with the diagnostic triad: hyperglycemia (blood glucose >250 mg/dL), metabolic acidosis (arterial pH <7.3 and serum bicarbonate <18 mEq/L), and elevated ketones in blood or urine. 1
Essential Diagnostic Criteria
The American Diabetes Association defines DKA by three key laboratory findings that must be present together 1:
- Blood glucose >250 mg/dL (though euglycemic DKA with glucose <250 mg/dL can occur, particularly with SGLT2 inhibitor use) 1, 2
- Arterial pH <7.3 (severe DKA has pH <7.00) 3, 1
- Serum bicarbonate <18 mEq/L (severe DKA has bicarbonate <10 mEq/L) 3, 1
- Elevated anion gap >10-12 mEq/L 1
- Positive ketones in serum or urine 3, 1
Clinical Presentation to Look For
The evolution of DKA is typically rapid, usually within 24 hours, which distinguishes it from hyperosmolar hyperglycemic state that develops over days to weeks 3, 1.
Key Symptoms:
- Polyuria, polydipsia, and polyphagia (classic triad of uncontrolled diabetes) 3, 4
- Nausea and vomiting (up to 25% have coffee-ground emesis from hemorrhagic gastritis) 3
- Abdominal pain (specific to DKA, not seen in HHS) 3
- Weight loss and severe fatigue 3, 4
- Fruity odor on breath (from acetone) 5
Physical Examination Findings:
- Kussmaul respirations (deep, labored breathing pattern specific to DKA) 3, 1
- Poor skin turgor (indicating dehydration) 3, 1
- Tachycardia and hypotension 3, 1
- Altered mental status ranging from full alertness to lethargy or coma 3, 1
- Hypothermia (if present, this is a poor prognostic sign) 3
Laboratory Tests to Order
Essential initial workup includes 1:
- Plasma glucose 1
- Arterial blood gases (for pH and bicarbonate) 1
- Serum ketones, preferably β-hydroxybutyrate 3, 1
- Electrolytes with calculated anion gap 1
- Blood urea nitrogen and creatinine 1
- Urinalysis and urine ketones 1
- Complete blood count with differential 1
Critical Point About Ketone Testing:
β-hydroxybutyrate measurement is strongly preferred over nitroprusside-based tests because standard urine dipsticks and nitroprusside tests do NOT measure β-hydroxybutyrate, which is the predominant ketone body in DKA 3, 1. This can lead to underestimation of ketosis severity 3.
Severity Classification
DKA severity is determined by the degree of acidosis 3:
- Mild DKA: pH 7.25-7.30, bicarbonate 15-18 mEq/L 3
- Moderate DKA: pH 7.00-7.24, bicarbonate 10-15 mEq/L 3
- Severe DKA: pH <7.00, bicarbonate <10 mEq/L 3, 1
Important Pitfalls to Avoid
Euglycemic DKA
Do not rule out DKA based solely on normal or near-normal glucose levels 1, 2. Euglycemic DKA (glucose <250 mg/dL) can occur in several situations:
- SGLT2 inhibitor use (most common cause currently) 3, 1, 2
- Pregnancy 1, 2
- Reduced food intake or ketogenic diets 1, 2, 6
- Alcohol use 1, 2
- Recent insulin administration 2
Normothermic or Hypothermic Presentation
Patients with DKA can be normothermic or even hypothermic despite having an underlying infection due to peripheral vasodilation 3. Do not exclude infection as a precipitating factor based on normal temperature alone.
Negative Nitroprusside Test
A negative urine ketone test does NOT rule out DKA if β-hydroxybutyrate is not measured, as the equilibrium shifts toward β-hydroxybutyrate production in DKA 3, 1.
Common Precipitating Factors to Investigate
Once DKA is diagnosed, identify the trigger 3, 1:
- Infection (most common precipitating factor) 3, 1
- New-onset type 1 diabetes or insulin omission 3, 1
- Myocardial infarction 3, 1
- Cerebrovascular accident 3, 1
- Medications: corticosteroids, thiazides, sympathomimetic agents 3, 1
- Alcohol abuse 3, 1
- Pancreatitis 3, 1
When to Suspect DKA in Diabetic Patients
Ketosis-prone individuals should check ketones when they have 3:
- Unexplained hyperglycemia 3
- Symptoms of ketosis: abdominal pain, nausea, vomiting 3
- Illness with deteriorating glycemic control 3
This includes patients with type 1 diabetes, history of prior DKA, or those treated with SGLT2 inhibitors 3.