Is 20 units of NPH insulin in the morning sufficient for a patient with type 2 diabetes mellitus, impaired renal function, and recent CRRT, who is also receiving hydrocortisone and a norepinephrine drip?

20 Units of Morning NPH is Likely Insufficient for This Complex Patient

For a critically ill patient with type 2 diabetes, impaired renal function, recent CRRT, receiving hydrocortisone and norepinephrine, 20 units of morning NPH insulin alone is inadequate and requires immediate intensification with a twice-daily NPH regimen plus prandial coverage to address steroid-induced hyperglycemia while accounting for altered insulin clearance from renal dysfunction. 1, 2

Why This Dose is Problematic

Steroid-Induced Hyperglycemia Demands Higher Doses

• Patients on glucocorticoids typically require 40-60% more insulin than standard dosing recommendations, making 20 units insufficient for adequate glycemic control 2
• Hydrocortisone causes disproportionate hyperglycemia during the day with peak effects 4-6 hours after administration, requiring NPH insulin administered concomitantly with steroids 1
• For steroid-induced hyperglycemia, NPH should be dosed at 0.1-0.2 units/kg per day as a starting point, which for an average 70 kg patient would be 7-14 units—but this patient's critical illness and high-dose steroids necessitate higher dosing 2

Renal Dysfunction Complicates Insulin Management

• Renal failure decreases clearance of exogenous insulin, creating a paradoxical situation where this patient needs more insulin for steroid-induced hyperglycemia but has prolonged insulin action from impaired clearance 3, 4
• Many patients with type 2 diabetes and end-stage renal failure need little or no therapy, but this patient's concurrent steroid use overrides this principle 4
• Dosing algorithms must be adjusted for renal failure to minimize hypoglycemia risk, requiring more frequent monitoring every 2-4 hours 1

Recommended Insulin Regimen

Convert to Twice-Daily NPH

• Switch from once-daily to twice-daily NPH with 2/3 of the total dose given in the morning and 1/3 given in the evening to match the hyperglycemic pattern from steroids 1, 2
• Calculate total NPH dose as 80% of current bedtime NPH dose when converting, though this patient is starting from morning dosing 1
• For this patient, consider starting with 30-40 units total daily NPH (20-27 units morning, 10-13 units evening) given the steroid requirement, but adjust based on glucose monitoring 2, 5

Add Prandial Insulin Coverage

• Add 4 units of short/rapid-acting insulin before each meal or 10% of the NPH dose to address postprandial hyperglycemia 1
• For patients on high-dose glucocorticoids, prandial insulin requirements often increase substantially and may require "extraordinary amounts" 1
• Consider a full basal-bolus regimen given the complexity of this case 1

Critical Monitoring Protocol

• Monitor blood glucose every 2-4 hours initially, particularly during afternoon and evening when steroid-induced hyperglycemia peaks 1, 2
• Target blood glucose of 140-180 mg/dL for critically ill patients, avoiding tight glycemic control which increases hypoglycemia risk 1
• If hypoglycemia occurs (<70 mg/dL), immediately reduce the corresponding insulin dose by 10-20% without waiting 1, 2

Special Considerations for This Patient

Renal Function and CRRT

• The recent CRRT suggests acute kidney injury or worsening chronic kidney disease, which dramatically alters insulin pharmacokinetics and increases hypoglycemia risk 3, 4
• Insulin clearance is decreased, requiring more conservative dose escalations of 1-2 units every 3 days rather than aggressive titration 1, 2
• 78% of hospitalized patients with hypoglycemia were using basal insulin, with peak incidence between midnight and 6:00 AM—this patient is at particularly high risk 1

Vasopressor Support

• Norepinephrine infusion indicates hemodynamic instability and critical illness, which increases insulin resistance and glucose variability
• Nutritional status must be assessed—if NPO or on enteral/parenteral nutrition, NPH can be administered 2-3 times daily with adjustments for feeding interruptions 1
• If enteral nutrition is interrupted, a 10% dextrose infusion must be started immediately to prevent hypoglycemia 1

Steroid Tapering Considerations

• When hydrocortisone is tapered or discontinued, reduce NPH dose by 10-20% immediately to prevent precipitous hypoglycemia 2, 5
• Insulin requirements decline rapidly after glucocorticoid cessation, requiring close monitoring for 24-48 hours 5
• Focus primarily on reducing the morning NPH dose when tapering morning steroids 2

Common Pitfalls to Avoid

• Do not continue single morning NPH dosing for steroid-induced hyperglycemia—this is the most common error and results in inadequate afternoon/evening coverage 5
• Do not use sliding scale insulin alone—this reactive approach is inferior to scheduled basal-bolus regimens 1
• Despite recognition of hypoglycemia, 75% of patients do not have their basal insulin dose changed before the next administration—be proactive with dose adjustments 1
• Avoid overtreatment given renal dysfunction—many type 2 diabetic patients with end-stage renal failure need minimal therapy once steroids are discontinued 4