What to do for a patient with persistent severe hyperglycemia despite initial insulin (Lispro) administration?

Immediate Management of Persistent Severe Hyperglycemia

This patient requires immediate transition to continuous intravenous insulin infusion, as subcutaneous insulin is inadequate for managing blood glucose levels exceeding 500 mg/dL that persist despite correction doses. 1, 2

Critical Assessment Required Now

• Check serum potassium immediately - if <3.3 mEq/L, hold all insulin and replace potassium first before any further insulin administration 2
• Assess hydration status - dehydration severely impairs insulin effectiveness and must be corrected concurrently 2
• Obtain venous blood gas, electrolytes, BUN, creatinine, and calculate effective serum osmolality to evaluate for hyperosmolar hyperglycemic state (HHS) or diabetic ketoacidosis (DKA) 1, 2
• Check for HHS criteria: glucose >600 mg/dL, pH ≥7.3, bicarbonate ≥15 mEq/L, effective serum osmolality ≥320 mOsm/kg 2
• Check for DKA criteria: glucose typically >250 mg/dL, pH <7.3, bicarbonate <15 mEq/L, positive ketones 2

Transition to IV Insulin Protocol

Subcutaneous insulin (including rapid-acting analogs like lispro) is insufficient for severe hyperglycemia >500 mg/dL and should be replaced with continuous IV insulin. 1, 2

IV Insulin Initiation

• Give IV bolus of regular insulin 0.1 units/kg body weight 1, 2
• Start continuous IV insulin infusion at 0.1 units/kg/hour 1, 2
• If glucose has not decreased by 50-75 mg/dL in the first hour, verify adequate hydration and double the insulin infusion rate hourly until achieving steady glucose decline of 50-75 mg/dL per hour 2

Concurrent Fluid Resuscitation

• Initiate isotonic saline at 15-20 mL/kg/hour for the first hour 1
• Adjust fluid rate to approximately 1.5 times 24-hour maintenance requirements after initial resuscitation 2
• Add 20-40 mEq/L potassium to IV fluids once renal function confirmed and potassium level known 2

Monitoring Requirements

• Check blood glucose every 1-2 hours until stable and achieving target decline 1, 2, 3
• Draw serum electrolytes, glucose, BUN, creatinine, osmolality, and venous pH every 2-4 hours 2
• Target glucose reduction of 50-75 mg/dL per hour - not faster to avoid complications 1, 2
• Decrease osmolality by no more than 3 mOsm/kg/hr to prevent cerebral edema 2

Glucose Target Adjustments

• Continue aggressive insulin infusion until glucose reaches 250 mg/dL (for DKA) or 300 mg/dL (for HHS) 2
• Then decrease insulin to 0.05-0.1 units/kg/hr and add dextrose 5-10% to IV fluids to prevent hypoglycemia while continuing to correct metabolic abnormalities 2

Critical Pitfalls to Avoid

• Do not continue subcutaneous insulin alone - this approach is ineffective for severe persistent hyperglycemia and delays appropriate treatment 1, 2
• Do not delay IV insulin while waiting for additional tests - this worsens metabolic derangement 1
• Do not allow glucose to fall faster than 75 mg/dL per hour - rapid correction increases complication risk 2
• Do not discontinue IV insulin prematurely - continue until metabolic stability achieved (glucose <200 mg/dL, normalized pH if acidotic, improved metabolic parameters) 1
• Do not forget potassium replacement - insulin therapy will lower serum potassium and hypokalemia is life-threatening 1, 2

Transition Back to Subcutaneous Insulin

• Only transition to subcutaneous insulin after metabolic stability is achieved 1
• Provide 1-2 hours overlap between IV and subcutaneous insulin to prevent rebound hyperglycemia 1
• Avoid sliding-scale insulin as monotherapy - use basal-bolus regimen instead 4, 5