What is the NPH (Neutral Protamine Hagedorn) insulin dose equivalent to 10 units of Novolog (insulin aspart)?

NPH Insulin Dose Equivalent to 10 Units of Novolog

There is no direct unit-to-unit conversion between Novolog (rapid-acting insulin aspart) and NPH insulin because they serve fundamentally different physiologic roles—Novolog provides prandial coverage for meals while NPH provides basal/intermediate-acting coverage. The question as posed cannot be answered with a simple numerical equivalent.

Understanding the Fundamental Difference

• Novolog (insulin aspart) is a rapid-acting prandial insulin with onset in 5-15 minutes, peak at 1-3 hours, and duration of 3-5 hours, designed to cover postprandial glucose excursions 1
• NPH is an intermediate-acting basal insulin with onset in 1-2 hours, peak at 4-6 hours, and duration of 12-18 hours, designed to provide background insulin coverage 2
• These insulins are not interchangeable on a unit-per-unit basis because they address different components of insulin therapy 1, 3

Clinical Context: What You're Actually Trying to Accomplish

If Converting from Prandial to Basal Coverage:

• When initiating NPH insulin in a patient not previously on basal insulin, start with 10 units per day OR 0.1-0.2 units/kg per day, regardless of prior prandial insulin doses 4
• The 10-unit one-time Novolog dose does not mathematically translate to an NPH dose—you must assess total daily insulin requirements and glycemic patterns 4

If the Patient Needs Both Basal and Prandial Coverage:

• Continue prandial insulin (like Novolog) for meal coverage AND add NPH for basal needs rather than attempting to substitute one for the other 4
• When adding prandial insulin to NPH, start with 4 units per meal or 10% of the basal insulin dose 4

Practical Algorithm for Tube-Fed Patients (Your Clinical Scenario)

Since you mention the patient is on tube feeds with good blood glucose control after a single 10-unit Novolog dose:

• For continuously tube-fed patients, NPH insulin given every 4-6 hours is more effective than rapid-acting insulin for glycemic control 5
• If transitioning to scheduled NPH coverage for continuous tube feeds, calculate total daily insulin requirement based on 0.1-0.2 units/kg per day, then divide into doses every 4-6 hours 4, 5
• For a 70 kg patient, this would be 7-14 units total daily, divided into 2-4 doses depending on the feeding schedule 4

Critical Pitfall to Avoid

• Do not attempt a 1:1 unit conversion between rapid-acting and intermediate-acting insulins—this approach ignores their different pharmacokinetic profiles and will result in either dangerous hypoglycemia or inadequate coverage 1, 3
• The single 10-unit Novolog dose tells you about acute prandial needs, not basal requirements—assess fasting glucose, pre-meal patterns, and total daily insulin needs to determine appropriate NPH dosing 4

Recommended Approach for Your Patient

• If blood glucose is in good range after one dose of Novolog and tube feeds are continuing, initiate NPH at 10 units per day (or 0.1-0.2 units/kg) divided appropriately for the feeding schedule 4
• Titrate NPH by 2 units every 3 days based on blood glucose monitoring to reach target without hypoglycemia 4
• If hypoglycemia occurs, reduce the NPH dose by 10-20% 4, 2