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Diabetes when you're unwell

When you have diabetes, it’s important to know how to cope when you’re unwell. Especially if you have to go into hospital.

Being ill can upset your diabetes management, so you need to know what to do to keep your blood glucose (sugar) levels as close to target as possible.

Some people will know these as diabetes sick day rules.

You'll need to know how to manage insulin or other diabetes medications, blood or urine tests, and your diet, and how to manage your diabetes when you're sick. This is really important if you go into hospital or if you need to take steroids as part of your treatment. Always tell the healthcare professionals treating you that you have diabetes. 

How illness affects diabetes

Illness and infections, as well as other forms of stress, can raise your blood glucose (sugar) levels to dangerously high levels. As part of the body’s defence mechanism for fighting illness and infection, more glucose is released into the blood stream. This can happen even if you’re off your food or eating less than usual.

People who don’t have diabetes just produce more insulin to cope. But when you’ve got diabetes, your body can’t do this. The symptoms of diabetes can add to those of the original illness or infection and make it much worse.

Feeling or being sick, or having diarrhoea can make your blood sugar levels drop, because you're not absorbing food as usual.

Being dehydrated when you have diabetes

Having a temperature or being sick can lead to dehydration. In some cases, severe dehydration and very high blood sugar levels can mean that you need to go into hospital

So it’s important to be prepared and follow our advice on coping when you're sick. You might want to give this information to a friend or family member, so they can help you if you get sick.

Your sick day rules - how to manage diabetes when you're sick

  • Don't panic – contact your diabetes team who will help you if you have any queries or if you are unsure about what to do.
  • Keep taking your diabetes medications – even if you don't feel like eating. But there are some medicines that you shouldn’t take as much of or stop taking altogether. Make sure you talk to your diabetes team or speak to a local pharmacist as soon as you’re feeling ill so they can give you the right advice.
  • Insulin may need to be increased or decreased when you're unwell, talk to your diabetes team for further advice on how to manage your insulin doses during illness.
  • If you check your blood sugar at home you'll probably need to do it more often – at least every four hours, including during the night. If you don't test your blood sugar levels at home, be aware of the signs of a hyper (hypergylcaemia).
  • Stay hydrated – have plenty of unsweetened drinks, and eat little and often.
  • If you have type 1 diabetes, it’s important to check for ketones. You usually check when your blood sugar level is 15mmol/l or more, or 13mmol/l if you use an insulin pump. But your diabetes team may have given you different targets, so regardless of what your blood sugars are saying – test for ketones. If you find ketones, contact your diabetes team.
  • If you take a certain type of diabetes tablet called SGLT2i and become unwell, you should stop taking these. You need to check your ketones and your blood sugars (if you've been told to do this and have the kit), and speak to your healthcare team. There are different types of SGLT2i tablets so check our list for all the brand names. Taking these tablets when you're not very well could increase your risk of developing diabetic ketoacidosis (DKA), so you need to know the symptoms to look out for.
  • Keep eating or drinking – if you can’t keep food down try eating little and often. Try snacks or drinks with carbohydrates in to give you energy. Try to sip sugary drinks (such as fruit juice or non-diet cola or lemonade) or suck on glucose tablets or sweets like jelly beans. Letting fizzy drinks go flat may help keep them down. If you're vomiting, or not able to keep fluids down, get medical help as soon as possible.

Get information about what to do if you're sick and have diabetes in languages other than English

See all of our information in other languages

If you’re taking steroids

Some conditions, like Addison's disease, severe asthma, rheumatoid arthritis, lupus and coronavirus are treated with steroids. If you have diabetes, taking high doses of steroids for periods of time can make your blood sugar levels rise. This is called steroid-induced hyperglycaemia. Your doctor or nurse will talk to you about this. They may ask you to make some changes to how you manage your diabetes, so that you can keep your blood sugar levels within your target range

Some people with coronavirus are being treated with a type of steroid called dexamethasone. Not everyone with coronavirus will need this steroid – it’s used in hospital or in virtual wards when someone is really unwell and needs help to breathe. Some people may be treated with dexamethasone at home. It works by reducing the inflammation that coronavirus can cause and supports your immune system to fight it.

While this works well for treating coronavirus, the side effects can affect blood sugar management. Dexamethasone makes your body more resistant to insulin, making your blood sugar levels go very high. If you’re given dexamethasone, you may need insulin to help reduce your blood sugar levels. If you already take insulin, you are likely to need to take more or take a different one that does a better job of bringing your blood sugars down. 

If you don’t have diabetes and are prescribed steroids, it’s important to know that taking this medication could cause diabetes to develop later on. This is called steroid-induced diabetes. We've got more information about the condition, including the symptoms to look out for. You can also speak to your healthcare team for more guidance and advice.

Protecting yourself against illness

There are things you can do to protect yourself against some illnesses, like flu. This includes getting your flu jab every year. And it may sound simple, but avoiding people who are sick and washing your hands often and thoroughly can help to protect yourself and others too.

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