Premixed Insulin

Reviewed by: HU Medical Review Board | Last reviewed: August 2023

Different types of insulin vary in how fast they work and how long they last. A combination of 2 different types of insulin in one medicine is called “premixed insulin.” Premixed insulin is a treatment option for people with type 2 diabetes (T2D).1

Insulin is not usually the first treatment for people with T2D. If you do start insulin, doctors may first recommend daily longer-acting insulin. Some people also need to take rapid-acting insulin before meals. In such cases, premixed insulin can combine both types to control blood sugar throughout the day.2

How does premixed insulin work?

Insulin is a hormone produced by the pancreas. It helps move glucose (sugar) from blood into other cells in your body. At mealtimes, the pancreas releases more insulin to handle higher blood sugar levels. This helps lower blood sugar, especially after meals.3

When you have T2D, your pancreas may not produce enough insulin. Your pancreas may also not produce more insulin at mealtimes. This can lead to high blood sugar throughout the day and after eating.3

Premixed insulin combines 2 types of insulin to control blood sugar throughout the day. It contains a rapid-acting insulin to control blood sugar after meals. This type starts working in 15 to 30 minutes and lasts 2 to 4 hours. Premixed insulin also contains a longer-acting insulin to control blood sugar between meals and overnight. This type starts working in 2 hours and lasts up to 24 hours.2,4

Premixed insulin makes treatment plans easier. It is more convenient than taking 2 types of insulin separately. It also reduces the number of injections per day. But premixed insulin has some drawbacks, including:2,4

  • Inability to change the dose of each type of insulin separately
  • Less flexibility for people who eat irregular meals
  • Less flexibility for changes to diet, exercise, or health


Most premixed insulin contains NPH insulin. NPH stands for "neutral protamine Hagedorn." This is an intermediate-acting insulin. Examples of premixed insulin include:1,3

  • Humulin® 70/30 and Novolin® 70/30: 70 percent NPH insulin, 30 percent regular human insulin
  • Humalog® Mix 50/50: 50 percent NPH insulin, 50 percent rapid-acting insulin lispro
  • Humalog® Mix 75/25: 75 percent NPH insulin, 25 percent rapid-acting insulin lispro
  • Novolog® Mix 70/30: 70 percent NPH insulin, 30 percent rapid-acting insulin aspart
  • Ryzodeg® Mix 70/30: 70 percent ultralong-acting insulin degludec, 30 percent rapid-acting insulin aspart

The right insulin for you depends on a number of factors that are personal to you. When deciding what type to prescribe, your doctor may ask you about:

  • Your blood sugar levels
  • Types of insulin that worked for you in the past
  • What types you can afford

What are the possible side effects?

Side effects vary depending on the specific insulin you are taking. The most common side effects of premixed insulin are:5,6

  • Low blood sugar (hypoglycemia)
  • Allergic reactions
  • Weight gain
  • Injection site reactions
  • Low levels of potassium in the blood (hypokalemia)
  • Skin thickening or pitting (lipodystrophy)
  • Itching and rash
  • Swollen hands or feet

Low blood sugar can be serious and life-threatening. Talk to your doctor if you notice signs of low blood sugar. These include:5,6

  • Blurry vision
  • Confusion
  • Dizziness
  • Headache
  • Slurred speech
  • Sweating

Allergic reactions can also be serious. Get immediate medical help if you have an allergic reaction. Symptoms include:5,6

  • Breathing problems
  • Rapid heartbeat
  • Rash over your whole body
  • Sweating

These are not all the possible side effects of premixed insulin. Talk to your doctor about what to expect when taking premixed insulin. You also should call your doctor if you have any changes that concern you when taking premixed insulin.

Other things to know

Take premixed insulin as your doctor describes. Premixed insulin is usually taken 1 to 2 times daily, before meals. Rotate where you inject to reduce the risk of side effects. Good spots to inject include your:2

  • Abdomen
  • Thigh
  • Upper arm
  • Buttocks

Check your blood glucose levels regularly. Talk to your doctor about your target level. Knowing these numbers can help you and your doctor see how well premixed insulin is working for you.2

Your doctor may adjust your dose over time. They may also switch you to a different type of insulin. Do not change your type or dose of insulin unless your doctor tells you to.2

Before taking premixed insulin, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs. Other drugs you take or medical conditions you have can make premixed insulin less safe. Also tell your doctor if you:5,6

  • Have allergies
  • Have any heart, liver, or kidney problems
  • Are pregnant or plan to become pregnant
  • Are breastfeeding

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