Insulin Side Effects

Adverse effects and allergic reactions to insulin are possible. Here's what you should know if you take insulin to control your diabetes.

insulin injectionEven though insulin occurs naturally in people who don't have diabetes, it's still possible to have an adverse reaction and there are side effects as well.

If you have diabetes your body has an insulin problem. In people without diabetes, insulin is a naturally-occurring hormone but in type 2s who do not use it efficiently or who have type 1 and don't produce it, insulin must be injected.

Insulin is made in a variety of forms (from rapid acting to long acting, etc) using a few different methods—through genetic engineering since 1982; withdrawn from the pancreas of deceased pigs or cows prior to that. Today there are more than 20 different types of insulin available in the United States. 

You may think you don't need to worry about side effects with insulin as it's a "natural" substance but when used to help control diabetes and blood glucose levels it's essentially a medication. And, as with all medications, side effects (or adverse events) are possible but do not occur in everyone. (If you feel brave and want to know more, read the prescribing information that accompanies your insulin.) 

It's important to note that while most people who use insulin do not experience significant side effects, you should be aware of the potential complications, just in case they occur.

Insulin-Related Hypoglycemia and Hypersensitivity 

The most common side effect is hypoglycemia; the most-rare side effect is hypersensitivity or allergy.  

How can injecting insulin cause hypoglycemia (low blood sugar) to happen? Insulin’s job is to essentially escort the sugar from the bloodstream into our brain, muscles, and nerves.  It thinks of nothing else, even if there is not enough sugar in the bloodstream to take. Meaning that if someone injects too much insulin, it will take too much sugar from the bloodstream, leading to low blood sugar.  Low blood sugar is defined as <70 mg/dL.  Common symptoms of low blood sugar include:

  • Shaky
  • Sweaty
  • Hungry
  • Headache
  • Blurred vision
  • Sleepy or tired
  • Dizzy or lightheaded
  • Confused or disoriented
  • Pale

If you notice any of these symptoms, test your blood sugar as soon as possible. If you are <70 mg/dL, treat with a fast-acting carbohydrate such as:

  • ½ cup juice or juice box
  • 4 glucose tablets
  • fun-size package of Skittles
  • 1 tablespoon honey

You can minimize the risk of hypoglycemia by eating regular meals, checking blood sugars frequently and working with a healthcare team to identify the right dose of insulin.

Hypersensitivities or allergies can occur from the insulin itself or the preservatives in it.  The chance of a hypersensitivity or allergy is VERY rare now that synthetic insulins are made in laboratories and animal insulins are no longer used. Estimates of incidence are between 0.1-3%.

There are two types of reactions: Immediate and delayed. Immediate reaction can occur locally at the site of the injection (typically swelling or redness) or be systemic and appear on the palm of the hands or soles of the feet. 

A delayed reaction occurs later than 1 hour and up to 24 hours later. The delayed reaction is usually transient and will resolve within a few weeks. 

If these rare sensitivities occur, what do you do? Be sure to contact your healthcare provider. He or she may suggest you try a different brand of insulin. If the reaction does not resolve, it may be recommended that you see an allergist to confirm the severity and explore treatment options.

If life-threatening side effects, such as a swollen tongue, tightness in your chest, difficulty breathing, dizziness, or fainting occur, get help immediately. Call 911.

Other Possible Insulin Side Effects

Unfortunately, insulin can cause weight gain, interactions with other medications, headaches, and nausea.

Also, each type of insulin has its own profile of possible side effects. When you begin using a new insulin, read the patient information insert that outlines side effects common to that particular type of insulin.

Regularly visiting the doctor's office and being aware of the side effects of insulin is vital to reducing the risks and complications posed by daily insulin injections. If you have any concerns or questions about the side effects of insulin, or simply want to educate yourself on the risks, we encourage you to consult a medical professional.



Updated on: October 12, 2018
Continue Reading
8 Snacks to Prevent Hypoglycemia