Diabetes is a common condition, affecting at least 4 to 5% of people in the UK. More than 10% of patients undergoing surgery have diabetes.
People with diabetes undergoing surgery need to have first-class integrated care from the time of initial referral, through to after their operation and before they go home to ensure their sugar levels are managed properly.
To help achieve this, NHS Diabetes are in collaboration with Diabetes UK as well as anaesthetists, surgeons, and diabetes specialists, to produce guidance based on the best available evidence, best practice, and patient experience. This guidance covers all stages of your pathway from GP referral to discharge, incorporating surgical outpatients, pre-operative assessment, hospital admission, surgery and post-operative care.
At the Royal National Orthopaedic Hospital we have adopted these guidelines with the aim of improving standards of care for diabetic patients undergoing surgery at our hospital.
This booklet will describe how to manage your diabetic medication in the lead-up to surgery, as well as giving general advice on preparation for your operation. Included is also information on what to expect regarding the management of your diabetes following discharge from the hospital and advice on what to do if you become unwell once you are at home.
Before your operation or procedure:
Please follow the instructions in the table marked “What to do with your medication before surgery/procedure”
If your operation is in the morning:
• Do not eat any food after midnight
• Drink clear fluids such as black tea or coffee (no milk), sugar free squash or water up to 5am
If your operation is in the afternoon:
If you have been specifically told that your operation (procedure) is in the afternoon, please contactthe pre-assessment unitto verify this, and if confirmed:
• Eat breakfast before 7am and take no food after this time
• Drink clear fluids such as black tea or coffee (no milk), sugar free squash or water up to 10am
When you travel to and from the hospital for your operation carry some glucose tablets or a sugary drink.
If you have any symptoms of low blood glucose levels such as sweating, dizziness, blurred vision or shaking please test your blood glucose if you are able to do so.
If it is less than 4mmol/L take four glucose tablets or 150mls of the sugary drink (this is the same as half a standard sized can of non-diet cola). Please tell staff at the hospital that you have done this because it is possible that your surgery may have to be rearranged for another day.
After your operation/procedure:
• If you take tablets for your diabetes - you will be offered food and drink when you feel able to eat. If you are eating and drinking normally you should resume taking your normal medication the morning after surgery.
• If you take insulin, your blood glucose will be checked and additional insulin given if necessary.
Your blood glucose levels may be higher than usual for a day or so:
• When you get home, if you feel nauseated or vomit and are unable to eat, please refer to the sick day rules leaflet on page 9
If you do not improve quickly and usually attend your local hospital for diabetes care please telephone the diabetes team during office hours Monday – Friday. Outside these hours please contact your GP practice or out-of-hours service. If you usually see your GP about your diabetes, please phone your GP practice.
Remember to bring with you to hospital:
• Glucose tablets or a sugary drink
• Blood glucose testing equipment (if you usually monitor your blood glucose)
• The medication you usually take for your diabetes (tablets/insulin/injections)
• Take your insulin or other medication as advised in this leaflet
• Monitor your blood glucose, 4 times per day if possible, if you have the equipment to do so. You should test more frequently if you are unwell, feeling or being sick.
• Your blood glucose may be higher than usual. This is not a concern if you are feeling well.
• If you are feeling unwell (particularly if you are being sick and unable to take food or medication) contact your usual diabetes team/GP surgery.
• If outside normal working hours contact your local out of hour’s service or go to your local hospital A&E department.
What should I do if I am unwell?
• NEVER stop taking your insulin or tablets – illness usually increases your body’s need for insulin
• TEST your blood glucose level every 2 hours, day and night
• TEST your urine for ketones every time you go to the toilet or your blood ketones every 2 hours if have the equipment to do this
• DRINK at least 100 mls water/sugar free fluid every hour – you must drink at least 2.5 litres per day during illness (approximately 5 pints)
• REST and avoid strenuous exercise as this may increase your blood glucose level during illness
• EAT as normally as you can. If you cannot eat or if you have a smaller appetite than normal, replace solid food during illness, with one of the following:
• 400ml milk
• 200ml carton fruit juice
• 150-200ml non-diet fizzy drink
• 1 scoop ice cream
• CONTINUOUS diarrhoea and vomiting, and/or high fever
• UNABLE to keep down food for 4 hours or more
• HIGH blood glucose levels with symptoms of illness (above 15 mmol/L - you may need more insulin)
• KETONES at ++2 or +++3 in your urine or 1.5 mmol/L blood ketones or more. (You may need more insulin). In this case, please contact the person who normally looks after your diabetes immediately.
18-275 © RNOH
Date of last review: November 2018
Date of next review: November 2020
Author: Preoperative Assessment Department
Page last updated: 10 July 2025