What is the difference between Novolin (NPH insulin) and Humalog (insulin lispro)?

Key Differences Between Novolin and Humalog Insulins

Novolin (NPH insulin) and Humalog (insulin lispro) are fundamentally different insulin types with distinct pharmacokinetic profiles: Novolin is an intermediate-acting basal insulin that peaks 6-8 hours after injection and lasts approximately 12 hours, while Humalog is a rapid-acting prandial insulin that begins working within 5 minutes, peaks at 1-2 hours, and lasts only 3-4 hours. 1

Pharmacokinetic Profile Comparison

Novolin (NPH Insulin)

• Onset: 1 hour after injection 1
• Peak action: 6-8 hours after administration 1
• Duration: Approximately 12 hours 1
• Classification: Intermediate-acting insulin 1
• Primary function: Provides basal insulin coverage to control fasting and between-meal glucose levels 1

Humalog (Insulin Lispro)

• Onset: 5 minutes after injection 1
• Peak action: 1-2 hours after administration 1
• Duration: 3-4 hours 1
• Classification: Rapid-acting insulin analog 1
• Primary function: Controls postprandial (after-meal) blood glucose excursions 2, 3

Clinical Use and Timing

Novolin Administration

• Must be administered on a fixed schedule, typically once or twice daily 1
• Requires patients to eat meals at set intervals to avoid hypoglycemia due to its peak action occurring many hours after injection 1
• The peak action is not related to mealtimes, creating risk of hypoglycemia if eating is delayed or physical activity increases 1

Humalog Administration

• Should be injected immediately before meals (0-15 minutes prior) 1, 2
• Does not require the 30-minute pre-meal waiting period needed with regular human insulin 2, 3
• Can even be administered immediately after meals in some circumstances 3
• Provides flexible injection scheduling that accommodates non-routine lifestyles 3

Hypoglycemia Risk Profile

Novolin carries a higher risk of hypoglycemia compared to long-acting insulin analogs like glargine, particularly because its peak action occurs many hours after injection and is not synchronized with meals. 1

Humalog demonstrates a lower risk of hypoglycemia, especially nocturnal episodes, compared to regular human insulin when used in basal-bolus regimens. 3, 4 In one crossover study, severe hypoglycemic episodes with coma were reduced to one-fifth in patients treated with Humalog compared to regular insulin 4

Appropriate Clinical Scenarios

When to Use Novolin (NPH)

• As part of a twice-daily premixed insulin regimen for patients who need simple, convenient dosing 1
• When cost is a significant barrier, as human insulins like NPH are substantially less expensive ($35 per vial) compared to insulin analogs ($174-300 per vial) 1
• For patients who cannot manage complex insulin regimens 1

When to Use Humalog

• For prandial (mealtime) coverage in basal-bolus regimens 1
• When postprandial glucose control is inadequate despite optimized basal insulin 1
• For patients requiring flexible meal timing or with unpredictable eating patterns 3
• In continuous subcutaneous insulin infusion (pump therapy) 5

Important Clinical Caveats

The disadvantages of intermediate-acting insulin like Novolin outweigh the advantages of tight blood glucose control in most modern diabetes management approaches. 1 Current guidelines favor long-acting insulin analogs (glargine, degludec, detemir) for basal coverage due to more consistent absorption and reduced hypoglycemia risk 1

Never mix Novolin and Humalog in the same syringe unless using a pre-approved premixed formulation. 1 Insulin glargine specifically cannot be mixed with any other insulin due to its low pH 6

When basal insulin exceeds 0.5 units/kg/day and postprandial hyperglycemia persists, adding prandial insulin like Humalog is more appropriate than continuing to escalate basal insulin alone. 1, 7