Skip to main content

Can you mix Humalog with Lantus?

Medically reviewed by Sally Chao, MD. Last updated on July 19, 2023.

Official answer


No, you should never mix Humalog (insulin lispro) and Lantus (insulin glargine) insulins together in the same syringe. Lantus should never be mixed in the same syringe with any other insulin or injectable medication. Mixing could make the characteristics of Lantus unpredictable and result in poor control of blood sugar.

There are different types of insulins. They are categorized according to how rapidly they start to work, when their peak effects occur and how long their effects last. Most individuals with diabetes need to use more than one kind of insulin each day to achieve good control of their blood sugar.

While some insulins may be mixed together in the same syringe to reduce the number of injections in a day, not all can.

  • Humalog is a rapid-acting insulin. On average, Humalog starts to work in about 15 minutes, with its peak effects occurring around 1 to 2 hours after injection. Its effects last between 2 and 4 hours usually. Timing of Humalog insulin injections should coordinate with mealtimes so that the insulin starts working when the sugars (carbohydrates) from food start to enter your system. Consequently, most individuals using Humalog will need to inject themselves with it three or four times a day. The exact dose of Humalog to inject is determined by several factors, including your current blood sugar and how many grams of carbohydrate are being eaten. So, the dose of Humalog given at each meal can vary.
  • Lantus is a long-acting insulin. Its effects on lowering blood glucose begin a few hours after injection, and last for about 24 hours. Lantus has a steady effect on lowering blood sugar over that time, and doesn't have a peak effect like many other insulins do. Lantus can be taken at any time during the day, but it should be taken at the same time each day. A person's dose of Lantus does not usually change very frequently.

It is very important to read the labels on each insulin vial each time it is used to avoid mix-ups.

Insulin is a hormone produced by the pancreas that helps you use or store energy produced from the food you eat. It is important for keeping your blood sugar levels within a desirable range. People with diabetes do not produce enough insulin or their bodies do not respond to insulin appropriately. Some people with diabetes need to inject themselves with insulin to keep their blood sugar within a healthy range. Insulin is usually injected under the skin (subcutaneously) on the stomach, upper thigh or upper arm.

Related Questions

  1. U.S. Food and Drug Administration (FDA). Lantus. Available at: [Accessed July 14, 2021].
  2. American Diabetes Association (ADA). Insulin Basics. Available at: [Accessed July 12, 2021].
  3. U.S. Food and Drug Administration (FDA). Humalog. November 2019. Available at:,205747s022s025s026lbl.pdf. [Accessed July 7, 2021].

Read next

Related medical questions

Drug information

Related support groups