What is the next step in management for a patient with severe hyperglycemia (blood glucose level 535 mg/dL) 30 minutes after administering 22 units of lispro insulin (rapid-acting insulin)?

Management of Persistent Severe Hyperglycemia After Rapid-Acting Insulin

Given a blood glucose of 535 mg/dL persisting 30 minutes after 22 units of lispro insulin, you should immediately administer an additional dose of rapid-acting insulin (4-6 units), ensure adequate hydration, and check for ketones to rule out diabetic ketoacidosis. 1

Immediate Assessment and Action

Check for Diabetic Ketoacidosis

• Measure serum or urine ketones immediately in any patient with blood glucose >297 mg/dL (16.5 mmol/L) who is on insulin therapy 1
• If ketones are present, suspect early ketoacidosis, contact a physician immediately, and consider ICU transfer 1
• If ketoacidosis is confirmed (pH <7.3, bicarbonate <18 mEq/L), transition to hourly subcutaneous lispro at 0.1 unit/kg/h or continuous IV regular insulin 2

Administer Additional Rapid-Acting Insulin

• Give an additional 4-6 units of lispro insulin subcutaneously immediately (approximately 20-25% of the initial dose) 1
• Lispro insulin reaches peak action at 30-90 minutes, so the initial 22-unit dose should be approaching its peak effect; however, severe hyperglycemia creates insulin resistance that may require higher doses 3, 4
• In the absence of ketosis, adding ultra-rapid analogue insulin with good hydration should be initiated rapidly 1

Ensure Adequate Hydration

• Begin aggressive IV fluid resuscitation if not already started, as dehydration worsens hyperglycemia and insulin resistance 1
• Severe hyperglycemia (>535 mg/dL) often indicates significant volume depletion requiring immediate correction 1

Monitoring Protocol

Short-Term Glucose Monitoring

• Recheck blood glucose every 30-60 minutes until glucose falls below 250 mg/dL 2
• Continue hourly lispro injections at 0.1 unit/kg/h (approximately 7-10 units for a 70-100 kg patient) until glucose <250 mg/dL 2
• Once glucose reaches 250 mg/dL, reduce lispro to 0.05-0.1 unit/kg/h until metabolic stability is achieved 2

Watch for Hypoglycemia

• The rapid correction of severe hyperglycemia carries risk of overcorrection and hypoglycemia 2
• If glucose drops below 70 mg/dL, administer 15-20 grams of oral glucose immediately if patient is conscious, or IV dextrose if unable to take oral 1

Investigate Underlying Causes

Assess Insulin Delivery Issues

• Verify the insulin was actually injected subcutaneously and not intramuscularly or leaked from injection site 3
• Check that the insulin has not expired and has been stored properly (refrigerated but not frozen) 3
• Confirm the patient used the correct insulin type and dose 3

Consider Precipitating Factors

• Evaluate for acute illness, infection, or stress that dramatically increases insulin requirements 1
• Review recent food intake—a large carbohydrate load may overwhelm even appropriate insulin dosing 5
• Assess medication adherence and timing of previous insulin doses 1

Longer-Term Management Considerations

Optimize Insulin Timing

• In hyperglycemic patients (glucose >180 mg/dL), lispro should ideally be administered 15-30 minutes before meals rather than at mealtime to achieve better postprandial control 5
• This pre-meal timing allows the insulin to begin acting as glucose from the meal is absorbed 5

Adjust Basal Insulin Regimen

• A glucose of 535 mg/dL suggests the patient's basal insulin regimen is grossly inadequate 6, 7
• Increase basal insulin by 10-20% (or 6-12 units if currently on 60 units) to improve fasting glucose control 6, 8
• Target fasting plasma glucose of 80-130 mg/dL, adjusting basal insulin by 2 units every 3 days until target achieved 6

Structured Prandial Coverage

• Replace any sliding scale insulin with scheduled mealtime rapid-acting insulin 6
• Start with 4-6 units or 10% of basal dose before the largest meal, titrating by 1-2 units twice weekly based on 2-hour postprandial glucose 6
• Progressively add prandial insulin to other meals if needed to achieve target HbA1c 6

Critical Pitfalls to Avoid

• Do not wait to see if the initial insulin dose "kicks in"—30 minutes post-lispro injection is near peak action time, and persistent severe hyperglycemia requires immediate additional insulin 3
• Do not assume absence of symptoms means absence of ketoacidosis—check ketones in all patients with glucose >297 mg/dL on insulin 1
• Do not give insulin without ensuring hydration—severe hyperglycemia with dehydration creates a vicious cycle of worsening insulin resistance 1
• Do not discharge the patient until glucose is <250 mg/dL and trending downward with stable vital signs 2