What is the recommended increase in NPH (Neutral Protamine Hagedorn) insulin dose for a patient currently taking 55 units of NPH insulin to cover 100 grams of carbohydrates, if their carbohydrate intake increases to 133 grams?

NPH Insulin Dose Adjustment for Increased Carbohydrate Intake

For a patient currently on 55 units of NPH insulin covering 100 grams of carbohydrates who is increasing to 133 grams, increase the NPH dose by approximately 5-6 units to a total of 60-61 units, representing a 10-11% increase that aligns with the 33% increase in carbohydrate load.

Calculating the Required NPH Dose Increase

The carbohydrate increase from 100g to 133g represents a 33-gram increment, which requires approximately 3-5 additional units of insulin based on the standard ratio of 1 unit per 10-15 grams of carbohydrate used in enteral nutrition. 1, 2

• Using the conservative end of the recommended ratio (1:10), the 33-gram increase would require 3.3 units 1
• Using the more aggressive ratio (1:15), this would require 2.2 units 1
• A practical middle-ground increase of 5-6 units (bringing total to 60-61 units) represents approximately a 10% dose adjustment, which falls within the ADA-recommended incremental adjustment range of 10-15% for insulin titration 1, 2

NPH Administration Schedule

For patients receiving continuous enteral nutrition, NPH should be administered twice or three times daily (every 8-12 hours) rather than once daily to provide more consistent coverage. 1

• Split the new total dose of 60-61 units into a twice-daily regimen: approximately 40 units in the morning (2/3 of total dose) and 20 units in the evening (1/3 of total dose) 1, 2
• This distribution pattern matches the typical insulin requirement pattern and reduces hypoglycemia risk 1
• Alternatively, for more stable coverage with continuous feeding, consider dividing into three equal doses of approximately 20 units every 8 hours 1

Correction Scale (Sliding Scale) Recommendations

Correctional insulin should be administered subcutaneously every 6 hours using regular human insulin or every 4 hours using rapid-acting insulin, in addition to the scheduled NPH doses. 1

A reasonable correction scale for a patient requiring 60 units of NPH daily would be:

• Blood glucose 150-200 mg/dL: 2 units regular insulin
• Blood glucose 201-250 mg/dL: 4 units regular insulin
• Blood glucose 251-300 mg/dL: 6 units regular insulin
• Blood glucose 301-350 mg/dL: 8 units regular insulin
• Blood glucose >350 mg/dL: 10 units regular insulin and notify provider 1

This scale assumes moderate insulin sensitivity; adjustments may be needed based on response 1

Titration Protocol After Initial Adjustment

Monitor blood glucose every 2-4 hours during the first 24-48 hours after making this adjustment to identify patterns of hyperglycemia or hypoglycemia. 3, 2

• If fasting or pre-feeding glucose remains >180 mg/dL after 3 days, increase the corresponding NPH dose by 2 units every 3 days until target glucose of 100-180 mg/dL is achieved 1
• If hypoglycemia occurs (glucose <70 mg/dL), immediately reduce the corresponding NPH dose by 10-20% without waiting 1, 2
• Target blood glucose range for hospitalized patients receiving enteral nutrition is 100-180 mg/dL 1

Critical Safety Considerations

If enteral nutrition is interrupted or discontinued, a 10% dextrose infusion must be started immediately to prevent hypoglycemia, as NPH has a duration of action of 12-18 hours. 1, 2

• Patients with type 1 diabetes must continue receiving basal insulin even if feedings are stopped to prevent diabetic ketoacidosis 1
• The risk of hypoglycemia increases significantly between midnight and 6:00 AM, so particular attention should be paid to overnight glucose monitoring 1
• NPH carries a higher risk of hypoglycemia compared to long-acting insulin analogs, especially in patients with impaired kidney function 1

Common Pitfalls to Avoid

• Failure to coordinate meal/feeding delivery with insulin administration is a frequent cause of both hyperglycemia and hypoglycemia 1
• Not adjusting insulin doses frequently enough—reassessment should occur every 3-6 months at minimum, but daily adjustments may be needed during acute illness or feeding changes 1
• Continuing the same basal insulin dose after a hypoglycemic event—75% of patients do not have their NPH dose adjusted after hypoglycemia, leading to recurrent episodes 1