Key Points

• Although there are not many medications that will significantly alter your blood glucose levels when you are on insulin, some will. It helps to know what these are.
• Let your doctor know that you have type 1 diabetes and are on insulin if he or she is prescribing medication for you
• Test your blood glucose frequently if you are starting on a medication that may change your blood glucose levels
• Seek advice on your insulin doses if a medication you take is changing your blood glucose levels
• Some medications come suspended in a syrup form. These syrups are often high in sugar. Check with the chemist whether they can give you a 'no sugar added' alternative
• Street drugs or marijuana may also cause changes to your blood glucose levels

Sometimes you may need medications for other things besides your diabetes. Some medications can effect your blood glucose levels. It pays to know what these medications are. Sometimes there is an alternative medication available that will not have the same effect. Sometimes you may need the medication anyway. But if you can anticipate the effect they may have on your blood glucose levels it will allow you to plan to manage this.

This section lists the commonest medications that may cause your blood glucose levels to change. It is not a complete list and you should always check with your doctor when you are starting any new medication.

Steroids

The commonest group of medications that may cause a big increase in your blood glucose levels are steroids.

Steroids are generally prescribed to dampen down inflammation. They are an extremely useful group of drugs and they are very effective in what they do. For some situations steroid medication is exactly what you may require. They are often used for people with arthritic conditions, for people with asthma or chest problems and for people with tissue swelling that's causing major problems for them.

Unfortunately, these very useful drugs will also make your blood glucose levels go high. In fact, many people first find out they have diabetes when they have been started on steroids for another reason and their blood glucose levels suddenly become high.

Why do steroids put my blood glucose up?

The way steroids put your blood glucose up is exactly the way stress hormones do. In fact one of the natural stress hormones we all produce is called 'glucocorticosteroid'. This hormone is a steroid.

Steroids cause your blood glucose to go high because they do two things:

• They block the action of your insulin where it moves glucose out of your blood stream and into your body cells
• They cause your liver to start manufacturing extra glucose to release into your blood. Both these actions cause your blood glucose to rise

Because you are unable to release extra insulin to start moving this extra glucose into your cells and muscles, your blood glucose goes high.

What should I do if I am prescribed steroids?

Firstly, tell the doctor who is prescribing the steroids that you have diabetes and are taking insulin. He or she may decide to try another group of drugs. Or, if they feel you really need the steroids, they will want to make a plan with you as to how to manage your blood glucose levels while you are taking the steroids.

When you start on steroids you should immediately start testing your blood glucose levels frequently (if you are not already doing so). Four or more times a day is ideal. That way you can see what is happening straight away. Visit the glucose meters & diabetes management section of this web site for more information.

It will almost certainly be necessary for you to increase your dose of insulin while you are on the steroids. Some health care professionals recommend that you make an increase to your morning insulin on the day you start the steroids. Others like you to wait until you see what your blood glucose levels are doing once you've started on the steroids.

Work with your diabetes nurse educator or your diabetes specialist to work out how to increase your insulin at this time.

Steroid medication is not usually given long term. You usually go on it for a course until the problem that the steroids are treating has settled down. Unless you are on a very low dose of steroids they won't be stopped straight away. The best way to stop steroid medication is to slowly reduce it over time.

If you have had to increase your insulin during the time you are on steroids you will almost certainly find that you will need to reduce it again as you come off the steroids. Once again, your blood glucose levels will tell you if this needs to happen. They will start to drop as the steroids are tailed off. Work closely with your diabetes nurse educator and/or doctor to get help to reduce your insulin during this time.

Oral Contraceptive Medications

Some oral contraceptives can cause your blood glucose levels to increase. The ones that can have this effect are ones that either have a high level of oestrogen in them, or those that contain levonogestral. Progesterone-only oral contraceptives tend to have very little effect on your blood glucose levels and are a good option.

Thiazide Diuretic Tablets

In high doses these medications can cause your blood glucose levels to go up. These drugs are usually only prescribed in low doses for people with diabetes.

Street Drugs and Marijuana

Taking street drugs or marijuana can indirectly cause alterations in your blood glucose levels. They may cause you to be unable to recognise the symptoms of low blood glucose levels or to mistake them for the effects of the drug. This can put you at risk of having a serious hypo as you are not alert to recognising or correcting it.

Some street drugs may cause you to eat either more food or less food. Many people feel the need to eat a great deal when they take marijuana.

Some party drugs (e.g., ecstasy) may cause you to feel as though you have boundless energy and can dance all night without feeling the need for rest or food. If you are on insulin this can be very dangerous as it can lead you to have a very serious hypo.

You may also be more likely to have a serious hypo when you are away from your normal family and friends. The people you are with may think you have collapsed as a result of the drug and not recognise that your blood glucose is low and you need urgent treatment.

Street drugs also come in very unpredictable strengths. It is often not possible to anticipate what kind of effect they will have on you, even if you have taken the drug before. The dose of the drug you are about to take may be either stronger or weaker than the last dose you took, and you have no way of knowing this.

For all these reasons it is not safe for you to experiment with taking these drugs. However, if you are taking these kind of drugs it is often helpful to find a diabetes nurse educator or diabetes medical specialist with whom you feel comfortable to discuss the safety issues around use of these drugs. Your GP may also be able to help.

Alcohol

The most common drug that can put you more at risk of having a low blood glucose level is alcohol.

Alcohol can block your liver's ability to correct your blood glucose level should it go low. Therefore, if you have a hypo when you have been drinking it is more likely to be a serious hypo.

Alcohol also blunts your ability to both look after yourself and also recognise a hypo. If you are under the effect of alcohol you may think that the feelings you are having are the effect of the alcohol. However, they may actually be the symptoms of a hypo. Similarly, you are more likely to forget to eat, or to eat less than normal if you have been drinking.

When you are on insulin you should (as far as possible) drink in moderation only. You should also always eat carbohydrate food when you are drinking. For more detail on managing alcohol safely when you are on insulin, see alcohol and diabetes.