What is the next step in insulin management for a patient with type 1 diabetes mellitus (T1DM) presenting with diabetic ketoacidosis (DKA) and requiring electrolyte correction?

Insulin Management for DKA: Intravenous Insulin Infusion

For a patient with type 1 diabetes presenting with DKA requiring electrolyte correction, initiate continuous intravenous insulin infusion at 0.1 units/kg/hour as the standard of care. 1, 2

Initial Insulin Therapy Protocol

Intravenous insulin is the preferred route for moderate to severe DKA because it provides predictable pharmacokinetics, allows for rapid titration, and ensures adequate insulin delivery in the setting of dehydration and poor tissue perfusion. 1

IV Insulin Administration

• Start continuous IV regular insulin infusion at 0.1 units/kg/hour without an initial bolus (or with 0.1 units/kg IV bolus if there is delay in setting up the infusion). 1, 2
• If plasma glucose does not fall by 50 mg/dL in the first hour, verify adequate hydration status; if acceptable, double the insulin infusion rate hourly until achieving a steady glucose decline of 50-75 mg/dL per hour. 2
• Continue IV insulin until complete DKA resolution (pH >7.3, bicarbonate ≥18 mEq/L, anion gap ≤12 mEq/L) regardless of glucose levels. 1, 2

Critical Glucose Management During IV Insulin

• When serum glucose reaches 250 mg/dL, add 5% dextrose to IV fluids (with 0.45-0.75% NaCl) while continuing insulin infusion. 1, 2
• Target glucose between 150-200 mg/dL until DKA resolution parameters are met. 1, 2
• Never stop insulin infusion when glucose normalizes—this is a common pitfall that perpetuates ketoacidosis. 2, 3

Concurrent Electrolyte Management

Potassium Replacement (Critical)

• Do not start insulin if K+ <3.3 mEq/L—aggressively replace potassium first to prevent life-threatening arrhythmias and respiratory muscle weakness. 2
• Once K+ ≥3.3 mEq/L and adequate urine output confirmed, add 20-30 mEq potassium per liter of IV fluid (use 2/3 KCl and 1/3 KPO₄). 1, 2
• Target serum potassium 4-5 mEq/L throughout treatment, as insulin therapy will drive potassium intracellularly. 1, 2
• Monitor potassium every 2-4 hours—inadequate monitoring is a leading cause of DKA mortality. 2

Fluid Resuscitation

• Begin with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour (approximately 1-1.5 L) during the first hour. 1, 2
• Aggressive initial fluid replacement is critical to restore tissue perfusion and improve insulin sensitivity. 2

Transition to Subcutaneous Insulin

When DKA is resolved and the patient can eat, administer basal insulin (glargine or detemir) 2-4 hours BEFORE stopping IV insulin infusion. 2, 4 This overlap period is essential to prevent:

• Recurrence of ketoacidosis
• Rebound hyperglycemia
• Premature termination of insulin therapy 2, 4

Transition Protocol

• Start a multiple-dose subcutaneous regimen combining short/rapid-acting insulin with intermediate/long-acting basal insulin. 1
• Continue IV insulin for 1-2 hours after initiating the subcutaneous regimen to ensure adequate plasma insulin levels. 1
• Adding low-dose basal insulin analog during IV insulin infusion can help prevent rebound hyperglycemia without increasing hypoglycemia risk. 2, 5

Alternative Approach: Subcutaneous Insulin (Limited Scenarios Only)

Subcutaneous rapid-acting insulin analogs may be considered ONLY for mild DKA (pH 7.0-7.3, bicarbonate 10-18 mEq/L) in hemodynamically stable, alert patients. 2, 4 However, this patient requires electrolyte correction, suggesting more significant metabolic derangement where IV insulin remains the standard of care. 2

When SC Insulin is Contraindicated

• Critically ill or mentally obtunded patients 2, 4
• Severe DKA (pH <7.0, bicarbonate <10 mEq/L) 4
• Hemodynamic instability or severe dehydration 4
• Cardiovascular compromise 1

Monitoring Requirements

• Draw blood every 2-4 hours for serum electrolytes, glucose, BUN, creatinine, osmolality, and venous pH. 1, 2
• Follow venous pH (typically 0.03 units lower than arterial pH) and anion gap to monitor acidosis resolution. 2
• Direct measurement of β-hydroxybutyrate is the preferred method for monitoring DKA resolution (nitroprusside method only measures acetoacetate and acetone, which can be misleading). 2

Common Pitfalls to Avoid

• Stopping insulin when glucose normalizes—this causes persistent or worsening ketoacidosis; add dextrose instead and continue insulin. 2, 3
• Inadequate potassium monitoring and replacement—leads to life-threatening arrhythmias. 2
• Abrupt discontinuation of IV insulin without basal insulin overlap—causes DKA recurrence and rebound hyperglycemia. 1, 2
• Starting insulin with K+ <3.3 mEq/L—correct hypokalemia first. 2