How to manage hyperglycemia in a diabetic adult on 40 units NPH (Neutral Protamine Hagedorn) insulin, 40 mg prednisone (corticosteroid) daily, with a carb ratio of 1:2.5, and recent glucose readings of 231 mg/dL at noon and 106 mg/dL at 6 PM?

Management of Steroid-Induced Hyperglycemia with NPH Insulin

Increase your NPH insulin dose by 20-30% (to approximately 50-52 units) given in the morning, and intensify your prandial insulin coverage by increasing your correction scale to 1 unit per 30-40 mg/dL above target, with particular attention to afternoon and evening glucose monitoring. 1, 2

Understanding Your Current Glycemic Pattern

Your glucose readings demonstrate the classic pattern of steroid-induced hyperglycemia:

• Noon glucose of 231 mg/dL indicates inadequate coverage during the peak steroid effect 1, 2
• Evening glucose of 106 mg/dL shows the typical normalization that occurs as prednisone's effect wanes 1, 3
• This diurnal pattern is characteristic: prednisone causes disproportionate hyperglycemia between midday and midnight, with blood glucose often normalizing overnight 1, 3

Specific NPH Dose Adjustment Algorithm

Step 1: Calculate Your New NPH Dose

• For patients on high-dose glucocorticoids (40 mg prednisone qualifies), insulin requirements typically increase by 40-60% above standard dosing 1, 2
• Your current 40 units NPH is likely insufficient given the noon glucose of 231 mg/dL 1
• Increase NPH to 50-52 units (a 25-30% increase) administered in the morning to coincide with prednisone administration 1, 4

Step 2: Optimize Your Prandial Coverage

• Your current carb ratio of 1:2.5 is extremely aggressive and may be appropriate for high-dose steroid therapy 1
• However, your correction scale needs intensification: use 1 unit of rapid-acting insulin for every 30-40 mg/dL above 150 mg/dL target during afternoon and evening 1
• The American Diabetes Association recommends more aggressive correction during the afternoon and evening when steroid effect peaks 1, 2

Critical Monitoring Protocol

You must monitor glucose every 2-4 hours initially, with special attention to these time points: 1, 2

• 2 PM (2 hours post-lunch): This captures the peak steroid effect and is the most critical reading 1, 2
• 6 PM (pre-dinner): Guides your dinner insulin dose 1
• Bedtime: Ensures you're not going into the night with hyperglycemia 2
• Fasting: While important, this reading alone is misleading in steroid-induced hyperglycemia 1, 2

Target Range

• Aim for 80-180 mg/dL throughout the day 1
• Your noon reading of 231 mg/dL is above target and requires intervention 1

Why NPH Insulin Is Specifically Recommended

NPH insulin's pharmacokinetic profile is uniquely suited for prednisone-induced hyperglycemia: 1, 2

• NPH peaks 4-6 hours after administration, which aligns perfectly with prednisone's peak hyperglycemic effect 1, 2
• When given in the morning with prednisone, NPH provides maximum coverage during the afternoon when you need it most 1, 5
• A randomized controlled trial demonstrated that NPH-based protocols achieve significantly better glycemic control than usual care in hospitalized patients on corticosteroids (mean glucose 226 vs 269 mg/dL, p<0.0001) 5

Common Pitfalls to Avoid

Pitfall #1: Relying on Fasting Glucose Alone

• Do NOT use only your fasting glucose to guide NPH dosing 1, 2
• This will lead to under-treatment of daytime hyperglycemia and potential nocturnal hypoglycemia 1
• Your evening glucose of 106 mg/dL might falsely reassure you that control is adequate 1, 3

Pitfall #2: Inadequate Afternoon Coverage

• The noon glucose of 231 mg/dL indicates your current regimen is insufficient 1
• Failing to anticipate the diurnal pattern is the most common error in managing steroid-induced hyperglycemia 2

Pitfall #3: Not Adjusting When Prednisone Dose Changes

• When prednisone is eventually tapered or discontinued, you must reduce NPH by 10-20% immediately to prevent hypoglycemia 1, 4
• Insulin requirements decrease rapidly after steroid discontinuation 1, 4

Additional Prandial Insulin Strategy

Given your noon glucose of 231 mg/dL despite a 1:2.5 carb ratio: 1, 2

• Consider increasing your lunch prandial insulin by 40-60% beyond your carb ratio calculation 1, 2
• For high-dose glucocorticoids, extraordinary amounts of prandial insulin are often needed 2
• Calculate: (grams of carbohydrate ÷ 2.5) + correction dose using the more aggressive 1:30-40 scale 1

When to Seek Urgent Medical Attention

Monitor for signs of severe hyperglycemia or hyperosmolar hyperglycemic state: 2

• Glucose persistently >300 mg/dL despite adjustments 2
• Increased thirst, frequent urination, confusion, or drowsiness 6
• Fruity breath odor, nausea, or vomiting 6