Contents

• Introduction

• What causes your blood glucose levels to rise?

• Symptoms of high blood glucose levels

• Managing your type 2 diabetes when you are ill

• If you manage your type 2 diabetes with tablets

• If you manage your type 2 diabetes with non-insulin injections

• If you manage your type 2 diabetes with insulin

• Hypoglycaemia (low blood glucose levels)

• When should I contact my diabetes care team?

• Useful resources

Introduction

If you have type 2 diabetes, it is very important that you know what to do when you are unwell. This is a guide, but please follow the advice of your local diabetes team if given. Advice may vary slightly from this content.

When you are unwell, your body becomes much more resistant to the insulin you produce yourself or take by injection. This means that your blood glucose levels can rise even if you are eating less than usual or have lost your appetite altogether. It is likely that you will need to adjust your medication. If you take sulphonylureas or insulin, you need to monitor your blood glucose levels very carefully.

We refer to this advice as ‘sick day guidance’.

What causes your blood glucose levels to rise?

Illnesses and other conditions that could increase your blood glucose levels include:

• Cold, flu or similar virus

• Stomach upset

• Sore throat

• Urine infection

• Chest infection

• Foot infection

• Abscess

• Broken bone

• Taking a steroid tablet or injections for another condition

• Having a period

• Diarrhoea

Symptoms of high blood glucose levels

• Increased thirst

• Dry mouth

• Passing a lot of urine

• Tiredness and lethargy

Managing your type 2 diabetes when you are ill

It is important to try to maintain stable blood glucose levels.

• Check your blood glucose: if you have a glucose meter, you should check your blood glucose levels at least four times a day: before each meal and before bed.

• Watch for low readings: if your blood glucose levels are lower than usual, you may need to reduce your insulin or sulphonylurea (e.g. gliclazide, glimepiride). This is rare but can happen if you eat a lot less than usual.

• Keep drinking: drink at least 2.5 litres of sugar-free liquid a day, ideally plain water.

• Eat if you can: try to eat your normal diet. If you have lost your appetite, you do not need to eat until you feel well enough to try, but keep sipping fluids to prevent dehydration. You should try to drink at least 100ml per hour.

If you manage your type 2 diabetes with tablets

If you have problems with your kidney function and you have been unwell with diarrhoea or vomiting for more than 24–48 hours and have paused medication, you should check with your GP whether you need a blood test before re-starting your medication.

Unfortunately, there may be no scope to increase your dose with these types of medication. If your blood glucose levels remain high for a few days or if you are concerned, consult your GP or diabetes care team.

If you manage your type 2 diabetes with non-insulin injections

If you use GLP-1 agonist injections, such as liraglutide (Victoza), dulaglutide (Trulicity) and semaglutide (Ozempic), or the combined GLP-1/GIP agonist injection tirzepatide (Mounjaro), you ✔ can continue to take them as normal, but it is important that you eat something after your injection.

⚠ However, if you have severe tummy pain, with or without vomiting, you MUST STOP these medications and seek urgent medical attention.

If you have problems with your kidney function, you may need to arrange a blood test with your GP to confirm that it is safe to start taking the medication again.

Unfortunately, there is no scope to increase your dose with this type of medication. If your blood glucose levels remain high for a few days or if you are concerned, consult your GP or diabetes care team.

If you manage your type 2 diabetes with insulin

Your blood glucose may rise above normal levels even if you are not able to eat your normal meals, so you should never stop taking your insulin. Follow these guidelines until you start to feel better:

• You should test your blood glucose levels every 2 to 4 hours and adjust your insulin as required (see below).

• To prevent dehydration, try to drink 2 to 3 litres of sugar-free liquids per day, especially plain water. This is approximately one glass every hour.

• If you are vomiting or are unable to eat solid carbohydrate foods, you can replace these with liquid carbohydrates, e.g. fruit juice or normal Coke.

• If you are not vomiting but have lost your appetite, try milky drinks, ordinary fruit jelly (not sugar-free), ice cream or custard.

• You should rest as much as possible.

• As you start to feel better, reintroduce solid foods and stop taking the sugary drinks.

Adjusting your insulin if your blood glucose levels are high

• If your blood glucose level is 4–10 mmol/L, take your usual insulin dose.

• If your blood glucose level is persistently higher than 10 mmol/L, you will have to take extra insulin, as per the examples below.

ℹ These instructions are given as examples, and you should primarily follow your healthcare team’s advice.

If you take twice-daily mixed insulin

If you use one of the twice-daily insulins below:

• Humulin M3

• NovoMix 30

• Humalog Mix 50

• Humalog Mix 25

Then consider this advice:

You should reflect on the previous 24 hours of glucose levels before making adjustments to the insulin dose. If you have a high blood glucose level, then you should adjust the dose at the time of day before the high blood glucose level.

Remember: morning insulin doses will impact pre-lunch and pre-dinner blood glucose levels, and evening insulin doses will impact on bedtime and pre-breakfast blood glucose levels.

However, when you are ill, it may be appropriate to take some extra insulin at the time of a very high blood glucose level. Your healthcare team can advise you on this.

Note: you will need to go back to your usual insulin doses once you are well again.

ℹ If you are unsure, consult your healthcare team.

Table 1: Adjusting your insulin dose for people taking twice-daily mixed insulin

If you take insulin 3–5 times a day, using both long- and quick-acting insulin

Use this advice if you take separate:

• long-acting insulin (e.g. Lantus, Abasaglar, Semglee, Humulin I, Toujeo, Degludec)

AND

• quick-acting insulin (e.g. NovoRapid, Fiasp, Humalog, Apidra, Trurapi, Humulin S) with meals.

Principles are as follows:

• If blood glucose is over 10 mmol/L, then take an extra dose of insulin using your quick-acting insulin as per the table below.

• If you are about to eat, then add this extra amount to your usual mealtime dose. (If you already use a mealtime calculation that takes into account your current glucose level, then keep using that rather than the table below.)

• Repeat doses at intervals of 2–4 hours if needed.

• Do not take another insulin dose within 2 hours unless advised by a healthcare professional.

• Follow the advice below until your blood glucose levels settle below 10 mmol/L.

Table 2: Adjusting your insulin dose for people taking quick-acting insulin

If you take once-a-day insulin

Use this advice if you take long-acting insulin once daily (e.g. Lantus, Abasaglar, Semglee, Insulatard, Humulin I, Toujeo, Degludec).

If blood glucose is over 10 mmol/L, then it may be appropriate to increase your insulin dose in a similar way to the above tables, but we recommend you discuss this first with your healthcare provider. They may want you to increase blood glucose monitoring and may want to change your insulin type.

Note: you may need to go back to your usual insulin doses once you are better.

Hypoglycaemia (low blood glucose levels)

Very occasionally, your blood glucose levels may fall when you are ill, and you may experience a hypoglycaemic episode (a ‘hypo’), i.e. a blood glucose level below 4 mmol/L.

You can find further information, including how to treat hypos, on our Hypoglycaemia page, or you can talk to your diabetes care team.

If you start to experience a number of episodes of hypoglycaemia (low blood glucose levels), you may need to reduce your insulin or the tablets you are taking. Get in touch with your healthcare team to discuss this as soon as possible.

It is important to remember that when you are ill, you must monitor your blood glucose levels closely.

When should I contact my diabetes care team?

⚠ You should talk to your diabetes care team or GP urgently if any of the following apply:

• You continue to vomit and/or are unable to keep anything down

• You have missed more than one meal

• Your symptoms do not improve within 24–48 hours

• You are worried about any aspect of your illness

• You need help with altering your insulin doses

Useful resources

More information is available on this subject in the What to do when you are ill leaflet.