What is the Difference Between Humalog and Novolog Insulins?

holding insulin and injection

What is the Difference Between Humalog and Novolog Insulins?

Basically, nothing. 

Humalog and Novolog are both synthetic, fast-acting forms of insulin that start working within 15 minutes but do not have long-lasting effects. They are usually paired with insulin that lasts longer such as intermediate or long-acting insulins. Humalog can be used and is approved in adults and children over the age of 3, but Novolog is approved for children two-years of age. 

Both are analogs of human insulin, and effects in people with diabetes appear identical. The cost and administration recommendations are similar. They should not be used together but are usually included in a regimen with intermediate and/or long-acting insulins.

Humalog and Novolog are used in people who have volatile glucose fluctuations, especially with meals. Others may be fine with intermediate and long-acting forms of insulin and use the lispro and aspart on an ‘as needed’ basis.

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Humalog and Novolog are types of human insulin

Lispro insulin is known as the brand Humalog and starts to work about 15 minutes after injection, reaches a peak in about 1 hour, and keeps working for 2 to 4 hours.

Aspart insulin is also known as the brand NovoLog and also starts to work about 15 minutes after injection but can be earlier, peaks in about 1 hour, and continues to work for 2 to 4 hours. Both are prescribed with long-acting or intermediate-acting insulins.

Humalog vs. Novolog

Insulin consists of two polypeptide (multiple proteins) chains (A and B) that are linked together by special chemical bonds called disulfide bonds. In the case of Humalog, this human insulin has been modified by substituting proline (an amino acid) for lysine in the 28th position on the B-chain while lysine is substituted for proline at position 29, also on the B-chain.

Novolog is human insulin that substitutes one position of proline for aspartic acid in position 28 of the B-chain. The purpose of these substitutions is to increase the absorption through the subcutaneous tissue to reach the blood faster compared to regular insulin. This helps regulate glucose levels right after meals yet lowers the risk that the glucose drops too low, causing hypoglycemia.

Onset of Action and Clearance of Humalog vs. Novolog in People with Diabetes Type 1

In one small study evaluating people with Type I Diabetes, there were no differences between Insulin lispro (Humalog) and Insulin Aspart (Novolog). Measurements of insulin in blood were similar 30 minutes after subcutaneous injection of either form. Both Humalog and Novolog were absent from the blood after approximately 4 hours. Concerning the effects on glucose, carbohydrate, and fat metabolism, both acted similarly. The study concluded that there were no significant differences in the two forms of insulin.

The only difference was in the timing of administration for the two forms. Humalog was best administered within 15 minutes of a meal or immediately after the meal, while Novolog should be administered 5-10 minutes before meals or very soon after the meal is started. The side effects, interactions, and adverse effects were the same for the two forms of insulin.

Humalog vs. Novolog: Who can use?

Humalog is used to treat type 1 and 2 diabetes in adults and children with type 1 who are at least three years old.

Novolog is used to treat type 1 and 2 diabetes in adults and in children who are at least two years old.

One difference is that a person can dilute NovoLog to administer a lower dose, but Humalog should not be diluted.

Humalog offers the following formulations:

  • 3 milliliter (ml) prefilled KwikPen
  • 3 ml cartridges
  • 3 ml vials
  • 10 ml vials

NovoLog offers the following formulation:

  • 3 ml FlexTouch
  • 3 ml FlexPen
  • 3 ml PenFill cartridges
  • 10 ml vials

Side Effects are affected by stress, exercise, and diet

  • Low blood sugar: monitor blood glucose before each meal and 1-hour later when first starting or changing a dose.
  • Headaches can be a sign of low blood glucose
  • Nausea and vomiting can be a sign of high or low blood glucose
  • Diarrhea
  • Weight gain: insulin drives glucose into cells and promotes fat deposition. Less weight gain is seen with tighter control and following the appropriate diet by avoiding simple sugars
  • Infections can dramatically alter the blood glucose levels, and insulin doses may need adjustments.
  • Exercising right before eating may result in lower blood glucose levels both before and after the meal so adjustments in the dose of Humalog or Novolog are indicated.
  • Low blood potassium is rare but may occur
  • Fluid retention and swelling are other rare side effects

Drug Interactions may occur with some blood pressure medications, beta-blockers, and androgens. 

Humalog vs. Novolog: Costs are similar

According to www.drugs.com, Humalog costs approximately $29 per milliliter (ml) or $87 for a 3ml vial containing 100 units/ml of Insulin lispro. Novolog costs approximately $277 for a 10ml vial that contains 100 units/ml of Insulin Aspart, which turns out to be $27.70 per ml. Both forms of insulin are available as cartridges and vials and need refrigeration. Humalog and Novolog now have generic versions that cost less than the brand names. Always check the actual chemical name, lispro or aspart, and buy from reputable pharmacies in the United States.


· Insulin comparison chart. (2018).

  • Humalog (Insulin Lispro) Revised 07/2016 Drugs.com Eli Lilly and Company https://www.drugs.com/pro/humalog.html
  • Types of Insulin for People with Diabetes Joslin Diabetes Center http://www.joslin.org/info/insulin_a_to_z_a_guide_on_different_types_of_insulin.html

· Novolog - insulin aspart injection, solution. (2018).

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