Illness Management

Sick Day Rules for People with Diabetes

People with diabetes don't get ill any more often than other people, but illness and infections can push up blood glucose and can often make you feel more unwell.

General sick day rules for people with diabetes

  • Never stop taking your insulin if you have Type 1 Diabetes
  • Continue to take your tablets and/ or insulin even if you are not eating much
  • Drink plenty of non-sugary fluids (4-6 pints per day) between meals to avoid dehydration
  • Seek medical advice sooner rather than later if you do not start to feel better after 2-3 days

What happens to my diabetes when I am ill?

 When you are ill your blood glucose levels tend to increase even if you are unable to eat or are being sick, this is because your body becomes more resistant to the insulin you inject. If you have Type 1 Diabetes this could increase your risk of developing Diabetic Ketoacidosis (DKA), a potentially life-threatening condition.

Although you may not feel like it, it is very important to monitor your diabetes closely to prevent such conditions occurring.

What is Diabetic Ketoacidosis (DKA)?

When blood glucose levels continue to increase it is due to a lack of insulin. Without treatment this couldlead to a serious condition called diabetic ketoacidosis, which requires urgent hospital treatment.

If there is not enough insulin, carbohydrate cannot be used to provide essential energy so the body breaks down its fat stores to use for energy instead.

This leads to the production of ketones (a type of acid), which are dangerous at high levels.

Ketones can be detected in the urine or blood.

As ketone levels increase you may feel very unwell, start vomiting or become short of breath or drowsy or confused. If left untreated it can be extremely dangerous.

 How can I prevent DKA

  • Never stop taking your insulin; we cannot survive without an adequate insulin supply
  • Act immediately - do not wait for your diabetes to become out of control
  • Make sure you always have access to ketone testing strips (either blood or urine) which have not reached their expiry date

What to I do with my medication?

If you are on tablets and or Injectables you should continue to take. If you take insulin then follow the guide below.

If you are on once or twice daily insulin:

If it is less than 13mmol/l- take your normal insulin dose

If it is more than 13mmol/l - take a larger insulin dose as directed below:

·       13-17mmol/l - add 2 extra units to each dose of insulin

·       17-22mmol/l - add 4 extra units to each dose of insulin 

·       More than 22mmol/l - add 6 extra units to each dose of insulin

If you are taking more than 50 units a day in total, you should double these adjustments.

Once you have given this initial increased dose, contact your GP, Practice Nurse or Diabetes Specialist Nurse for advice if you feel unsure about adjusting your insulin doses further.

Continue to test your blood glucose every 4 hours

If the level is less than 13mmol/l, adjust the insulin back down to your normal doses.

The doses should be decreased again gradually as the illness subsides.

If you are on a Basal Bolus insulin regime:

If you are feeling unwell, or your blood glucose levels are regularly above 13mmol/l, test your blood or urine for ketones and follow the guidance as indicated below.

Some abbreviations/terms used in guidance:

QA:  Quick-Acting insulin e.g. Humalog, Novorapid or Apidra, usually taken with meals

BI: Background Insulin, or long-acting Insulin e.g. Lantus, Levemir, Insulatard or Humulin I.

TDD: Total Daily Dose - Total amount of insulin taken usually in a day (i.e. all quick-acting insulin taken with meals and background insulin doses added together)

Corrective: extra quick-acting insulin taken to 'correct' a raised glucose level. If you are unsure what your sensitivity is to corrective insulin is, assume 1 extra unit may reduce your glucose by up to 3mmol/l.

No ketones - Minor Illness

If blood ketone levels are less than 1.5 mmol/l ('Trace' or negative in urine), this is classed as a Minor Illness.

Blood glucose is usually within target or slightly elevated.

Insulin Adjustment

  • Test blood glucose and ketones every 4 hours
  • Take usual dose of quick-acting insulin with meals if eating, plus corrective insulin if blood glucose raised
  • Use corrective dose of quick-acting insulin to reduce blood glucose even if not eating
  • May only need background insulin if not eating. Give usual dose of background insulin (you could consider an increase in dose by 1 to 2 units if you continue to be unwell for more than a day).

Ketones present - Severe Illness

If blood ketone levels are 1.5mmol/l or higher ('+' or more in urine) this is classed as a Severe Illness.

Blood glucose is usually above 13mmol/l.

Insulin adjustment

  • Test blood glucose and ketones every 2 hours
  • Calculate total daily dose (TDD) from previous day
  • Give additional quick-acting (QA) insulin as indicated in boxes below
  • Once ketones less than 1.5mmol/l, follow Minor Illness guidance as above



+++ to ++++ (urine)




+ to ++ (urine)

1.5-3.0mmol/l (blood)

Give 10% TDD as QA insulin every 2 hours plus usual QA insulin with meals plus usual BI

Give 20% TDD as QA insulin every 2 hours plus usual QA insulin with meals plus usual BI

Calculating Total Daily Dose (TDD) of insulin

Total Daily Dose (TDD) is the total amount of insulin you take in a typical day. This includes background (BI) and quick acting (QA) insulin.

Example of how to calculate TDD:  

Previous days total amount of QA insulin = 26 units.

Previous days total amount of BI insulin = 24 units.

Total Daily Dose (TDD) 26 units + 24 units = 50 units

Suggestion: make a note of your total daily dose of insulin from yesterday (or a typical day and using table below calculate 10% and 20% of this dose:

Table for use as a guide to help calculate either 10% or 20% of your TDD





































If you are vomiting and your blood glucose is not responding to the additional insulin, you may need to be admitted to hospital.

At all times remember, whatever your blood glucose level is, if you cannot keep drinking, have persistent vomiting, become drowsy, breathing becomes deep & rapid then immediately seek medical advice dial 999

Food and fluid intake during illness

During illness you may not wish to eat normal meals. If this is the case, try to have alternative food or drinks that contain carbohydrate and are easy to digest, e.g. ice cream/milky drinks/soup. Having some carbohydrate may help reduce further ketone formation.

Sip sugar-free fluids (at least 100ml each hour) to reduce the risk of dehydration.

If you are unable to eat, use sugary drinks such as fruit juice or lucozade to treat any hypos.

If you are vomiting, you do not need to eat until you feel well enough to try, but keep sipping fluids to prevent dehydration.

What if things are not improving?

Seek urgent medical attention if:

·       you continue to vomit and/or are unable to keep fluids down

·       your ketone levels do not improve despite increased insulin doses

·       you become drowsy or confused

·       you or your carers feel unable to manage your diabetes

·       you are feeling more unwell

You may need to seek medical advice to treat the cause of your illness.

© 2022 Your Diabetes

Website by See Green