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Diabetes and pancreatic cancer

Your pancreas produces a hormone called insulin, which helps to control your blood sugar level. When you digest food and drink, carbohydrate is broken down into glucose, which is a type of sugar. This passes into your blood, and is used by the body.

Normally, insulin controls the blood sugar level. But if you have pancreatic cancer or you have had all or part of your pancreas removed, your pancreas may not produce enough insulin. This means your blood sugar level may not be properly controlled, and you may develop diabetes. Diabetes is a condition where the amount of sugar in your blood is too high. 

If your blood sugar level is too high (hyperglycaemia), you may feel very thirsty, pass more urine, get headaches and feel tired.

Your pancreas also produces a hormone called glucagon which also helps to control your blood sugar level. If your pancreas doesn’t produce enough glucagon when you need it, your blood sugar level may drop and become too low (hypoglycaemia). You may feel hungry, shaky or sweaty. This is more common if you have had surgery to remove your pancreas, such as a Whipple's operation. 

Managing diabetes

If you are diagnosed with diabetes, you should see specialist diabetes or pancreatic dietitian. You may also see a diabetes nurse for help with managing any medication prescribed.

It’s important that you get specialist advice, because managing your diabetes may be more difficult because of your pancreatic cancer. Your dietitian and diabetes nurse should discuss any changes to your diet and treatment with you.

You may need to monitor your blood sugar level, and take tablets or have insulin injections to stop your blood sugar level becoming too high or too low. 

There are different types of diabetes, and information on the internet may not be right for you, because of your pancreatic cancer. Speak to your doctor, nurse or dietitian for advice about what to eat and how to manage your diabetes. 

If you were already diagnosed with diabetes, having pancreatic cancer may make your diabetes more difficult to control and changes may need to be made to your medications. You may also need to monitor your blood sugar level more often, to make sure it is controlled. It is important that you keep in regular contact with your diabetes specialist, particularly when starting new treatments for your cancer.

If you are well, have a good appetite and have not lost weight, you may be told to follow a healthy, balanced diet. Diabetes UK have information about food that you may find helpful. If you have been following a particular diet to control your diabetes, this may no longer be so necessary, but discuss this with your medical team. 

If you have lost weight or are struggling to eat, the usual advice about diet and diabetes may not be right for you. You may need more calories (energy) in your diet to help you put weight back on. This may include eating foods that increase your blood sugar level. Your diabetes will need to be managed around this. For example, your diabetes medication may be increased if necessary.

Diabetes and pancreatic enzyme supplements

If you are having problems digesting your food, you may have low blood sugar levels. This is because you won’t be able to digest and absorb sugars from your food properly. Once you start taking enzyme supplements, your blood sugar level may start to rise because you will start to digest your food properly again.

Speak to your doctor, nurse or dietitian about this. You may need more diabetes medication.

If you forget to take enzyme supplements with food, your blood sugar level may drop. If this happens remember to take your enzyme supplements with your next snack or meal. 

What else can affect my blood sugar level?

If you are taking steroids, these can cause your blood sugar level to rise. Your medical team will need to monitor this.

If you have symptoms such as sickness or diarrhoea, and take tablets for your diabetes, you might not be able to absorb the medication properly. Speak to your doctor, nurse or dietitian if you have these symptoms.

If you are prescribed nutritional supplements, be aware that some of these are high in sugar. Speak to your dietitian or nurse before taking these if you have diabetes as your medication may need to change.

Exercising can lower your blood sugar level, as your body uses the sugar as energy. If you are fit enough to do a lot of exercise, and have diabetes, you may need to eat more when you are exercising. If you are not very fit, this may also be necessary if you are doing gentle physical activity.

Managing diabetes if you have pancreatic cancer can be difficult and confusing. If you have any questions or concerns, speak to your cancer nurse, dietitian, doctor or diabetes nurse.

You can also call our specialist nurses on our Support Line.

More diet and pancreatic cancer information 

Updated November 2017

To be reviewed November 2019

Information Standard