How Do Intermediate-Acting Insulins Work?

Reviewed on 1/10/2022


Intermediate-acting insulins (also known as “isophane insulin”) are a class of drugs used to control high blood sugar in people with type 1 (T1DM) and type 2 diabetes mellitus (T2DM) along with a proper diet and exercise. T1DM or insulin-dependent diabetes is an autoimmune condition in which the body does not produce insulin and therefore cannot control the amount of sugar in the blood. However, T2DM is a slowly progressive metabolic disorder caused by a combination of genetic and lifestyle factors that promote chronically elevated blood sugar levels.

Intermediate-acting insulin is a human-made form of insulin, often taken in combination with short-acting insulin. Its action is typically initiated within the first hour of injecting, followed by a period of peak activity lasting up to seven hours.

Insulin is a peptide hormone produced by the beta cells of the pancreas to help metabolize food and use it for energy throughout the body. After a meal, insulin promotes the uptake of glucose (a type of sugar found in many carbohydrates) from the blood into internal organs and tissues such as the liver, fat cells, and skeletal muscles. It allows the body to use glucose for energy; helps in the storage of glucose in the liver, fat, and muscles; and regulates the body’s metabolism of carbohydrates, fats, and proteins.

Isophane insulins are administered subcutaneously (under the skin) in the stomach area, the thighs, the buttocks, or the back of the upper arm typically once or twice a day before meals.

Isophane insulins work in the following ways:

  • They act as basal insulin and stimulate the liver to promote hepatic glycogen synthesis (process of glucose production in the liver) and fatty acid metabolism for lipoprotein synthesis.
  • They help in increasing the cellular intake of glucose in the liver, adipose tissue, and skeletal muscles.
  • In skeletal muscles, they promote glycogen and protein synthesis.
  • In adipose tissues, they help in triglyceride (a type of fat) synthesis and regulate lipolysis (breakdown of fats and other lipids by hydrolysis to release fatty acids) by inhibiting triglyceride hydrolysis.


Intermediate-acting insulins are indicated to improve glycemic control in patients with T1DM and T2DM along with a proper diet and exercise


Some of the common side effects include:

  • Injection site reaction (pain, redness, and irritation)
  • Weakness
  • Tiredness
  • Nausea
  • Other rare side effects include:
  • Weight gain
  • Hypokalemia (low blood potassium level)
  • Muscle cramps
  • Dizziness (feeling faint, weak, or unsteady)
  • Swelling of the arms, hands, feet, ankles, or lower legs
  • Shortness of breath
  • Tremors (a rhythmic involuntary shaking movement in one or more parts of the body)
  • Paresthesia (an abnormal sensation, typically tingling or pricking caused by pressure on or damage to peripheral nerves)
  • Lipodystrophy (a problem with the way the body uses and stores fat)
  • Hypoglycemia (low blood sugar level)
  • Sudden sweating
  • Fast heartbeat
  • Blurred vision
  • Tingling in hands/feet

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.


Generic and brand names of intermediate-acting insulins include:


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