A diabetic patient with hyperglycemia, dehydration, and a history of vomiting and omitted insulin, which treatment approach is correct?

Low Molecular Weight Heparin Should Be Administered

The correct answer is C: Low molecular weight heparin should be administered. This patient presents with diabetic ketoacidosis (DKA), and thromboprophylaxis is a critical component of management that is often overlooked.

Why Option C is Correct

• Patients with DKA are at significantly elevated risk for thromboembolic complications due to dehydration, hyperosmolality, and hypercoagulability 1
• The American Diabetes Association guidelines emphasize that hospitalized patients with diabetes, particularly those with acute hyperglycemic crises, require venous thromboembolism prophylaxis 2
• Low molecular weight heparin should be administered unless contraindicated to prevent potentially fatal pulmonary embolism and deep vein thrombosis 1

Why the Other Options Are Incorrect

Option A: Total Body Potassium Will Be Elevated - FALSE

• Total body potassium is severely depleted in DKA, despite initially normal or elevated serum levels 1
• The acidosis drives an extracellular shift of potassium, creating falsely reassuring serum levels while total body stores are critically low 1
• Once insulin therapy begins, potassium shifts back intracellularly, and serum levels can drop precipitously, causing life-threatening arrhythmias 3, 1
• Potassium replacement must begin once renal function is assured and serum potassium is known, typically adding 20-40 mEq/L to IV fluids 2

Option B: Rehydration and Insulin Should Always Commence Immediately Concurrently - FALSE

• This is dangerously incorrect and represents a common pitfall that can cause death 3, 1
• If initial serum potassium is <3.3 mEq/L, insulin therapy MUST be delayed until potassium is restored to prevent life-threatening cardiac arrhythmias, cardiac arrest, and respiratory muscle weakness 3, 1
• The correct sequence is: begin isotonic saline at 15-20 mL/kg/hour while holding insulin, confirm renal function, aggressively replace potassium until K+ ≥3.3 mEq/L, then start insulin 3
• Only after potassium is safe should insulin be initiated with an IV bolus of 0.1 units/kg followed by continuous infusion at 0.1 units/kg/hour 2, 3

Option D: Intravenous Sodium Bicarbonate Should Be Considered - FALSE

• Several studies have shown that bicarbonate use in DKA made no difference in resolution of acidosis or time to discharge 2
• Bicarbonate is generally not recommended and may be considered only in severe acidosis with pH <6.9 2
• The acidosis resolves with insulin therapy and fluid resuscitation; bicarbonate adds unnecessary risk without benefit 2

Option E: Arterial Blood Gases Would Reveal a Reduced Anion Gap - FALSE

• DKA is characterized by an ELEVATED anion gap metabolic acidosis, not reduced 2
• The accumulation of ketoacids (β-hydroxybutyrate and acetoacetate) causes the anion gap to increase 2
• Resolution of DKA requires anion gap ≤12 mEq/L, along with glucose <200 mg/dL, bicarbonate ≥18 mEq/L, and venous pH >7.3 3

Complete Management Algorithm for This Patient

Immediate Actions (First Hour)

1. Begin isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour to restore circulatory volume 2, 3
2. Obtain STAT laboratory evaluation: plasma glucose, electrolytes (especially potassium), venous blood gas, BUN/creatinine, serum ketones (β-hydroxybutyrate preferred), osmolality, urinalysis, CBC, ECG 2, 3
3. Administer low molecular weight heparin for thromboprophylaxis 1
4. DO NOT start insulin yet - wait for potassium results 3, 1

Potassium Management (Critical)

• If K+ <3.3 mEq/L: Continue aggressive fluid resuscitation, add 20-40 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO4), obtain ECG, and delay insulin until K+ ≥3.3 mEq/L 3, 1
• If K+ ≥3.3 mEq/L: Proceed with insulin therapy and add potassium to fluids 3

Insulin Therapy (After Potassium is Safe)

• IV bolus of regular insulin 0.1 units/kg followed by continuous infusion at 0.1 units/kg/hour 2, 3
• Target glucose decline of 50-75 mg/dL per hour 3
• If glucose doesn't fall by 50 mg/dL in first hour, verify hydration status and double insulin infusion rate hourly until achieving steady decline 2

Ongoing Monitoring

• Check blood glucose every 2-4 hours 3
• Monitor electrolytes, venous pH, and anion gap every 2-4 hours 2, 3
• When glucose reaches 250 mg/dL, change fluids to 5% dextrose with 0.45-0.75% NaCl plus potassium 2

Resolution Criteria

DKA is resolved when ALL of the following are met 3:

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

Transition to Subcutaneous Insulin

• Administer basal insulin (glargine or detemir) subcutaneously 2-4 hours BEFORE stopping IV insulin to prevent DKA recurrence 2, 3
• Continue IV insulin for 1-2 hours after subcutaneous insulin is given 3
• Never discontinue IV insulin without prior basal insulin administration - this is the most common error leading to DKA recurrence 3, 1

Common Pitfalls to Avoid

1. Starting insulin before checking potassium - can cause fatal arrhythmias 3, 1
2. Stopping IV insulin without prior subcutaneous basal insulin - causes DKA recurrence 3, 1
3. Forgetting thromboprophylaxis - increases risk of potentially fatal pulmonary embolism 1
4. Using bicarbonate routinely - no proven benefit and may cause harm 2
5. Correcting osmolality too rapidly (>3 mOsm/kg/hour) - increases risk of cerebral edema 1