Desensitization therapy is a technique used to reduce a patient’s allergic reactions to allergy-provoking substances. This therapy can be used to help with substances individuals cannot avoid. People with diabetes may be prescribed this treatment to help overcome allergies to insulin, a medication that may be prescribed to control glucose (blood sugar).

An allergy occurs when the immune system identifies a generally harmless substance as being dangerous and produces antibodies to fight the substance. Any substance that causes this reaction is called an allergen.

In some cases, an allergic person can avoid contact with the allergen. However, when people become allergic to medications necessary for their health, such as insulin, avoidance may not be possible. Desensitization is the process of reducing or eliminating a patient’s sensitivity to an allergen. This is accomplished over time by injecting the patient with small but increasing amounts of the allergen. When this process is used to reduce allergic reactions to medications, it is called drug desensitization therapy.

Insulin allergies are rare. They usually appear in one of two forms:

• Local reaction. This reaction is limited to the injection site. Symptoms include red and itchy skin.
  
  
• Systemic reaction. This is a reaction that affects the entire body. Symptoms include hives, red patches across the body, galloping heartbeat and breathing difficulties.

Drug desensitization is considered only when there is no alternative type of insulin or other medication available. This process must be carefully supervised by a physician, sometimes in a hospital.

The patient continues to have allergic reactions to the drug while desensitization takes place. Antihistamines, corticosteroids, epinephrine or other medications may be given to suppress any allergic symptoms while the desensitization process is completed. 

Insulin desensitization is commonly performed using synthetic insulin with a rapid desensitization protocol, an increased time frame in which desensitization is achieved in a matter of hours or days.

Severe allergic reactions, including anaphylaxis (reactions involving two or more body systems), are sometimes possible during drug desensitization therapy. Desensitization may not be an option for patients at risk for such reactions. In such cases, patients will probably need to consult with their physician about alternative forms of therapy – for example, switching from animal insulin to human insulin, or taking drugs such as corticosteroids to reduce antibody activity.