Managing diabetes if you have pancreatic cancer – information about type 3c diabetes

If you have pancreatic cancer or have had surgery to remove the cancer, you may have a type of diabetes called type 3c diabetes. This information is for people with type 3c diabetes.

We also have information about diabetes as a symptom before people are diagnosed with pancreatic cancer, and diabetes as a risk factor of pancreatic cancer.

Diabetes is a condition where the amount of glucose (which is a type of sugar) in your blood is too high. The amount of glucose in your blood is called your blood sugar level. You may also hear it called your blood glucose level.

The pancreas normally produces two hormones called insulin and glucagon which keep the amount of glucose in your blood at the right level. If you have pancreatic cancer, you may not produce enough of these hormones. This means that your blood sugar level may become too high – this is diabetes. 

Some people may have had diabetes before they were diagnosed with pancreatic cancer. This might be type 1 or type 2 diabetes – read more about these below. If you already had diabetes, pancreatic cancer can change how the diabetes is managed.

What is type 3c diabetes?

There are different types of diabetes. You may have heard of type 1 and type 2 diabetes. Type 3c diabetes is different to these, and may be treated differently. It is caused by diseases that affect how the pancreas works. This means that people with pancreatic cancer and pancreatitis (inflammation of the pancreas) may get type 3c diabetes, and also people who have had surgery to remove part of the pancreas. It is sometimes called pancreatogenic diabetes.

What are insulin and glucagon?

Insulin and glucagon are both hormones. Hormones are chemical messengers in the blood which do specific things in the body. Insulin and glucagon control how much glucose is in your blood.

When you digest food and drink, carbohydrates are broken down into glucose. This passes into your blood and is used as energy or is stored in the body.

  • Insulin reduces the amount of glucose in your blood. It does this by moving the glucose from the blood into cells in the body, where it is either stored or used for energy.
  • Glucagon helps to increase the amount of glucose in your blood if it becomes too low, by releasing glucose that is stored in your liver.

If you have type 3c diabetes, your pancreas will make less insulin and glucagon than your body needs. If your whole pancreas has been removed, your body will not make any insulin or glucagon.

Why is type 3c diabetes different to type 1 and type 2?

Type 3c diabetes is different to type 1 diabetes and type 2 diabetes.

  • People with type 1 diabetes produce very little or no insulin, but normal levels of glucagon. People with type 3c diabetes produce less of all the hormones from the pancreas, including insulin and glucagon. If you have had your whole pancreas removed (a total pancreatectomy), you won’t produce any insulin or glucagon.
  • People with type 2 diabetes can’t use the insulin their pancreas makes properly. People with type 3c diabetes can use the insulin but don’t make enough of it. If their whole pancreas has been removed, they won’t make any insulin.

The different types of diabetes need to be treated differently. This means that the usual treatment for type 1 or type 2 diabetes may not be right for you if you have pancreatic cancer. If you already had type 1 or type 2 diabetes before being diagnosed with pancreatic cancer, your diabetes may now need to be treated differently. Most people with type 3c diabetes will need to take medicine, which may be tablets or insulin injections.

You may find that type 3c diabetes isn’t as well known as type 1 or type 2. A lot of the information you may find about diabetes is for people with type 1 or 2 diabetes, and may not be relevant to you. For example, there is a lot of information about losing weight for people with type 2 diabetes – this won’t be relevant to people with type 3c diabetes who have lost weight or are struggling to put weight back on.  

Diabetes and problems digesting food

If you have type 3c diabetes, you may also have problems digesting your food. Problems with digestion may be caused by the cancer or surgery to remove the cancer. The pancreas makes enzymes which break down your food. If you have pancreatic cancer, your pancreas may not produce enough of these enzymes, or they may be blocked from getting to the part of your bowel where they are needed for digestion.

You can take capsules to replace the enzymes that your pancreas would normally make. This is called pancreatic enzyme replacement therapy (PERT), and will help you digest your food.

If you have problems digesting your food, you may have low blood sugar levels. This is because you won’t be able to digest carbohydrate in your food properly or absorb the sugars. Once you start taking the enzymes, your blood sugar level may rise because you will start to digest your food again. This can change how your diabetes needs to be managed, and it may need to be monitored more regularly. If you notice your blood sugar levels have gone up, speak to your diabetes team as they may need to change your medicine. Read more about blood sugar levels.

Read our fact sheet about diabetes

You can read more about diabetes, including how to manage it, in our fact sheet:

Diabetes if you have pancreatic cancer: Information about type 3c diabetes.

Download our diabetes fact sheet

What are the symptoms of diabetes?

If your blood sugar level becomes high, this can cause symptoms. In the short term these symptoms can include:

  • feeling thirsty
  • passing urine (peeing) more often
  • tiredness
  • confusion
  • blurred vision
  • headaches and irritability
  • losing weight
  • wounds taking longer to heal
  • getting infections more easily.

High blood sugar levels can also increase the risk and severity of infections like colds, thrush infections, wound infections and urine infections. If you are having chemotherapy or surgery, it is important that your blood sugar level is properly managed. This will reduce the risk of infection and help wounds to heal after surgery.

“It is worthwhile looking out for symptoms of diabetes. It was only after I mentioned my partner’s unusual increased thirst and the need to go to the loo that he had a blood test which confirmed the diagnosis.”

Who treats diabetes?

Who you see to treat your diabetes may depend on services in your local area. Make sure you know who to  contact about managing your diabetes. If you are not sure, ask your pancreatic cancer doctor or nurse who to talk to about your diabetes.

If you are diagnosed with diabetes, you may see a specialist dietitian, such as a diabetes, pancreatic or oncology dietitian, to help you manage your diabetes. If you haven’t seen a specialist dietitian, ask your doctor or nurse to refer you to one. You may also see a diabetes specialist nurse who will teach you how to monitor your blood sugar levels and help manage your diabetes medicine. Your GP may also help manage your diabetes.

It can be difficult and confusing to manage diabetes if you have pancreatic cancer. Your dietitian and diabetes nurse will help you manage your blood sugar levels and give you advice about how to live well with your diabetes.

Questions about diabetes?

If you have any questions, it is important that you speak to your dietitian or diabetes nurse. You can also speak to our specialist nurses on our free Support Line who can explain more about managing diabetes.

Speak to our nurses
Specialist nurse Nicci

Questions to ask your doctor, nurse or dietitian


  • Why have I developed diabetes?
  • Do I have type 3c diabetes?
  • How is my diabetes different to type 1 or 2 diabetes?
  • How should I manage my diabetes?
  • Who can help me manage my diabetes?
  • Will I need to monitor my blood sugar levels? How should I do this?
  • Will I need to take medicine or insulin?
  • How do I take insulin?
  • How should I manage my diet if I have diabetes and pancreatic cancer?
  • Will having surgery mean I develop diabetes?

Acknowledgements and references


This information has been developed for people with pancreatic cancer by the Support and Information Team at Pancreatic Cancer UK. It is based on “Type 3c diabetes and reduced appetite”, which was produced by Laura McGeeney, Pancreatic Specialist Dietitian, Addenbrooke’s Hospital, Cambridge and Victoria Mann, Hepatobiliary Specialist Dietitian, Oxford.

We would like to thank the following people who reviewed this information.

  • Neil Bibby, Macmillan Senior Specialist HPB Dietitian, Manchester Royal Infirmary, Manchester University NHS Foundation Trust
  • David Bourne, Specialist Dietitian, Freeman Hospital
  • Anna Burton, Senior Specialist Pancreatic Dietitian, Leeds Teaching Hospitals NHS Trust
  • Susie Hamilton Diabetes Specialist Dietitian, Manchester University NHS Foundation Trust
  • Adele Hug, Freelance Specialist Oncology Dietitian
  • Mary Mahon, Specialist Surgical Dietitian, Freeman Hospital, Newcastle Upon Tyne
  • Victoria Mann, Hepatobiliary Specialist Dietitian, Oxford
  • Laura McGeeney, Pancreatic Specialist Dietitian, Addenbrooke’s Hospital, Cambridge
  • Margaret Palmer, Diabetes Specialist Nurse, Leeds Teaching Hospitals
  • Mary Phillips, Hepato-pancreatico-biliary Specialist Dietitian, Royal Surrey County Hospital NHS Foundation Trust
  • Sue Vyoral, Macmillan Oncology Dietitian, Royal Surrey County Hospital Guildford
  • Pancreatic Cancer UK Lay Information Reviewers
  • Pancreatic Cancer UK Specialist Nurses

References

Email us at publications@pancreaticcancer.org.uk for references to the sources of information used to write this information.

Updated April 2021

Review date April 2023