If you have diabetes, it is very important that you know what to do when you are ill.
When you are ill your body becomes much more resistant to the insulin you produce or take by injection. This means that your blood glucose levels can rise and it is likely that you will need to adjust your medication. You therefore need to monitor your blood glucose levels very carefully. We refer to this as ‘sick day guidance’.
What could cause my 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
- Urinary infection
- Chest infection
- Broken bone
- Taking a steroid tablet or injections for another condition
Symptoms of high blood glucose
- Increased thirst
- Dry mouth
- Passing a lot of urine
- Tiredness and lethargy
Managing your diabetes when you are ill
If you manage your diabetes with diet
- If you manage your diabetes with diet, you follow general advice around rehydration but will not be at risk of hypoglycaemia (low blood sugar). There is no need to monitor blood glucose or take extra carbohydrate. If you develop any worrying symptoms, contact your healthcare team.
If you manage your diabetes with tablets
- You should continue to take them except under circumstances described below.
- If you have a meter, you should test your blood glucose levels at least four times a day.
- Drink at least 2.5 litres of sugar-free liquid a day, especially water.
- 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 drink at least 100 ml per hour.
If you are taking metformin and/or an SGLT2 inhibitor (a drug ending with ‘-ozin’) but you have sickness and/or diarrhoea, you should not take these drugs until you start eating and drinking normally again. If you have problems with your kidney function you will need to arrange a blood test with your GP to confirm that it is safe to start taking the medication again.
If you manage your diabetes with non-insulin injections
If you have non-insulin injections such as Exenatide (Byetta) or Liraglutide (Victoza), Dulaglutide (Trulicity) you should continue to inject as normal, but it is important that you eat something after your injection.
If you have diarrhoea and/or sickness you should not take these drugs until you start eating and drinking normally again. If you have problems with your kidney function you will 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, or call NHS 111 (England) / NHS 24 (Scotland).
If you manage your 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 two to four hours and adjust your insulin as required (see below).
- To prevent dehydration try to drink two to three 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. Lucozade, fruit juice, 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.
Each of these contains approximately 10 grams of carbohydrate:
- Milk 1 cup (200 ml)
- Fruit juice (unsweetened) 1 small glass (100 ml)
- Lucozade 1 small glass 110 ml
- Coke (full-sugar version) 1 glass 100 ml
- Lemonade (full-sugar version) 1 glass 200 ml
- Ice cream 1 scoop (50 g)
- Jelly (normal fruit-flavoured) 2 tablespoons (65 g)
- Yoghurt (fruit, low calorie) 1 small carton (120 g)
- Yoghurt (plain) 1 small carton (120 g)
- 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 level is less than 10 mmol/L take your usual insulin dose.
- If your blood glucose level is persistently higher than this, you will have to take extra insulin.
- If you take quick-acting insulin (Novorapid, Humalog Apidra, Humulin S) then increase each dose as detailed in Table 1 below until your blood glucose levels settle below 10 mmol/L.
- If you are on a twice-daily mixed insulin regimen you can increase both doses as detailed below.
Table 1: Adjusting your insulin dose
Blood Glucose Level
What to do
10 - 16.9
take an extra 4 units
17 - 28
take an extra 6 units
28 or more
take an extra 8 units & consult your Diabetes team
Very occasionally your blood glucose levels may fall when you are ill and you may experience a hypoglycaemic episode (a ‘hypo’). If this happens and your blood glucose level is below 4 mmol/L.
You can find further information, including how to treat hypos, at Hypoglycaemia or you can talk to your diabetes care team.
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:
- If you continue to vomit and/or are unable to keep anything down
- If you have missed more than one meal
- If your symptoms do not improve within 24–48 hours
- If you are worried about any aspect of your illness
- If you need help with altering your insulin doses
More information is available on this subject is available from trend UK on what to do when you are unwell here and type 2 diabetes and diabetic ketoacidosis here.