How steroids can affect your diabetes

Steroids are drugs that are commonly used to treat cancer.

They can increase blood sugar levels. Before you start taking any steroids, talk to your doctors about the best way to keep your blood sugar at a good level.

If you don’t already check your blood sugar, you will need to start checking it. If you do already, you will need to check it more often.

You should talk to your diabetes team or your GP as soon as possible if:

  • your blood sugar levels are high (more than 15 mmol/l) on more than two or three occasions
  • you feel generally unwell or develop any of the symptoms of diabetes, such as being really thirsty, having blurred vision, passing a lot of urine or feeling very tired.

You may need to change the way you manage your diabetes while you are taking steroids. Your diabetes team can give you advice.

Your doctor or nurse may change your steroid treatment. You should never stop taking your steroids without talking to your cancer doctor first.

What are steroids?

Steroids (sometimes called corticosteroids) are substances that are naturally produced in the body. They are made by the adrenal glands. There are two adrenal glands – one sits on top of each kidney.

Steroids help control many different functions in our bodies, such as the way the body uses food. They regulate our immune system and the balance of salt and water in our bodies. They also help to reduce inflammation.

Steroids can be manufactured into drugs and used for cancer treatment. They can be given as tablets or injections. There are different types of steroids and they all have different effects on the body. Common types of steroids used in cancer treatment are hydrocortisone, dexamethasone, methylprednisolone and prednisolone.

Steroids can be used:

  • as part of your treatment to help destroy cancer cells and make chemotherapy more effective
  • to help reduce an allergic reaction to certain chemotherapy drugs
  • in low doses as anti-sickness drugs
  • to improve your appetite.


How steroids can affect your diabetes

Steroids can increase blood sugar levels in people who have diabetes and also in people who don't have diabetes. This can happen because:

  • the liver produces more sugar during steroid treatment
  • steroids make sugar less able to move out of the blood
  • your body may become resistant to insulin while you are taking steroids.

If you are taking steroids, you may find it more difficult to control your blood sugar level. How your blood sugar is affected will depend on:

  • the type of diabetes you have
  • how you normally manage your diabetes
  • which steroids you are taking
  • how you are taking the steroids – your blood sugar may start to increase a day or two after taking steroid tablets, but could increase within a few hours of having a steroid injection
  • the dose of steroids – the higher the dose, the more likely your blood sugar will increase
  • the time of day you take the steroids
  • how long you are taking the steroids for.

If you don’t have diabetes but are at risk of developing it, you will be asked to monitor your blood sugar levels while you are taking steroids. Some people may need to start treatment to help control their blood sugar. Your doctor or nurse will talk to you about this.


Controlling your blood sugar when taking steroids

If you have diabetes, it is very important that your blood sugar levels are tested during steroid treatment.

Before you start taking any steroids, talk to your doctors about the best way to keep your blood sugar within your target range. If you don’t already check your blood sugar, you will need to start checking it. If you do, you will need to check it more often.

Your doctor may also suggest you check your urine for ketones, especially if you have type 1 diabetes. Ketones are chemicals that can sometimes build up in the body when there is a severe lack of insulin. Ketones are toxic to the body and large amounts can be very serious. A high level of ketones in the body is called diabetic ketoacidosis (DKA). It mainly affects people with type 1 diabetes, but can affect anyone with diabetes who uses insulin. It can also affect people who control their diabetes with tablets and their diet, but this is rare.

Keep a record of your blood sugar levels and when you take the steroids. This is so you can see if there is a pattern. You can share the record with your doctors and nurses.

When you first take the steroids, it is a good idea to make sure you have enough blood-testing equipment with you at home. We have more information about planning ahead before you start cancer treatment.

You should talk to your diabetes team or your GP as soon as possible if:

  • your blood sugar levels are high (more than 15 mmol/l) on more than two or three occasions
  • you feel generally unwell or develop any of the symptoms of diabetes, such as being really thirsty, having blurred vision, passing a lot of urine or feeling very tired.

If your blood sugar level continues to be high while you are taking steroids, your doctor or specialist nurse may change the dose of steroids. They may also change the time you take the steroids or suggest spreading the dose out during the day.

Your diabetes doctor may also change the way you control your diabetes:

  • If you use your diet to control your diabetes, you may need to start taking tablets to control your blood sugar.
  • If you already take tablets, you may need to increase the dose or start using insulin for a short time.
  • If you already use insulin, you may need to increase the dose or use a different type of insulin.

Correction doses of insulin can be used to reduce very high blood sugars. These may not work as well when you are taking steroids. Your diabetes team can give you advice and may suggest you take more insulin.

You should never stop taking your steroids without talking to your cancer doctor first.

The amount of steroids you take as part of your cancer treatment will eventually be reduced and stopped. Ask your cancer doctor or nurse about this, so you can change your diabetes treatment.


Long-term risks of steroids

Sometimes steroids used to treat cancer can lead to permanent diabetes in people who were at risk of developing diabetes. This means that although the blood sugars may reduce once you stop taking the steroids, the diabetes may continue to need treatment. This is called steroid-induced diabetes and is like type 2 diabetes.