What should be done for a patient with severe hyperglycemia who shows minimal response to insulin lispro (insulin lispro) therapy?

Management of Severe Hyperglycemia with Minimal Response to Insulin Lispro

This patient requires immediate transition to intravenous regular insulin infusion, as subcutaneous lispro is failing to control severe hyperglycemia (BG >500 mg/dL), and you must simultaneously assess for diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS). 1

Immediate Assessment Required

Before proceeding with additional insulin, you must check the following critical parameters:

• Verify potassium level is >3.3 mEq/L - if potassium is <3.3 mEq/L, hold all insulin and replace potassium first, as insulin will drive potassium intracellularly and can cause life-threatening hypokalemia 1
• Confirm adequate fluid resuscitation is ongoing - dehydration significantly impairs insulin effectiveness and must be corrected 1
• Assess for HHS: glucose >600 mg/dL, pH ≥7.3, bicarbonate ≥15 mEq/L, effective serum osmolality ≥320 mOsm/kg 1
• Assess for DKA: glucose >600 mg/dL, pH <7.3, bicarbonate <15 mEq/L, positive ketones 1

Why Subcutaneous Lispro is Failing

Subcutaneous insulin absorption is unreliable in severe hyperglycemia due to dehydration and poor tissue perfusion. 2 The patient's minimal 15 mg/dL drop over 30 minutes with 22 units of lispro indicates:

• Inadequate hydration impairing subcutaneous absorption 1
• Possible severe insulin resistance requiring much higher doses 2
• Need for continuous IV insulin to achieve steady glucose decline 1

Transition to IV Insulin Protocol

Switch immediately to IV regular insulin infusion:

• Initial IV bolus: 0.15 U/kg regular insulin 1
• Continuous infusion: Start at 0.1 units/kg/hr 1
• Expected response: Plasma glucose should decrease by 50-75 mg/dL in the first hour 1
• If inadequate response: Verify hydration is adequate, then double the insulin infusion rate hourly until achieving steady glucose decline of 50-75 mg/dL per hour 1

Target Glucose and Transition Points

• Continue aggressive IV insulin until glucose reaches 250 mg/dL (for DKA) or 300 mg/dL (for HHS) 1
• Then decrease insulin to 0.05-0.1 units/kg/hr and add dextrose 5-10% to IV fluids 1
• Do not allow glucose to fall faster than 50-75 mg/dL per hour to prevent cerebral edema and other complications 1

Fluid Management Protocol

• Maintain IV fluid rate at approximately 1.5 times 24-hour maintenance requirements for smooth rehydration 1
• Decrease osmolality by no more than 3 mOsm/kg/hr to avoid cerebral edema 1
• Once renal function confirmed and potassium known, include 20-40 mEq/L potassium in fluids 1

Critical Monitoring Requirements

Draw blood every 2-4 hours for:

• Serum electrolytes, glucose, BUN, creatinine, osmolality, and venous pH 1
• Venous pH is adequate for monitoring (typically 0.03 units lower than arterial pH) - repeat arterial blood gases are generally unnecessary 1

Common Pitfalls to Avoid

• Do not continue subcutaneous insulin in severe hyperglycemia - absorption is too unreliable and unpredictable 2
• Do not rely on urine or serum ketone measurements by nitroprusside method to assess DKA response - β-hydroxybutyrate is not measured and conversion to acetoacetate during treatment may falsely suggest worsening ketosis 1
• Do not give additional subcutaneous correction doses when glucose is not responding - this leads to insulin stacking and unpredictable hypoglycemia once perfusion improves 2
• Do not allow rapid glucose correction - maintain 50-75 mg/dL per hour decline to prevent complications 1

Why Your Current Approach is Inadequate

Giving an additional 5 units of subcutaneous lispro and rechecking in one hour is insufficient because:

• Subcutaneous absorption remains unreliable in this severely hyperglycemic, likely dehydrated state 2, 1
• Lispro has rapid absorption when conditions are normal but unpredictable pharmacokinetics in severe hyperglycemia 3
• This patient requires continuous IV insulin to achieve the steady, controlled glucose decline needed in severe hyperglycemia 1
• Waiting another hour delays definitive treatment and prolongs the metabolic crisis 1

Admit this patient immediately for IV insulin infusion, aggressive fluid resuscitation, and close monitoring for DKA/HHS complications. 1