Management of type 2 diabetes
before and after bariatric surgery
Information for patients, relatives and carers
Introduction
This leaflet provides information about how to manage your type 2 diabetes before and after your
bariatric surgery. It is important to have good control of your diabetes before you have surgery, as this
will help your body to heal. This leaflet is not meant to replace the consultation between you and your
medical team, but aims to help you understand more about what is discussed. If you have concerns or
questions about any aspect of your recovery please speak to a member of the medical team.
Please note: patients who normally take tablets for their type 2 diabetes should read the sections
on pages 1 and 2, marked with a ‘T’. Patients who normally inject insulin should read the
sections on pages 2 and 3, marked with an ‘I’. All type 2 patients should read the information
from page 4 onwards.
Before surgery for those who normally take tablets (T)
You will see the bariatric team before surgery, at your pre-assessment appointment (this is the
appointment after the group meeting). You will be advised about the non-diabetic medication you should
take on the day of your surgery.
Your surgeon or dietitian will give you a diet sheet at your pre-assessment appointment providing
information about what you should eat before and after surgery. You will be told how long you need to
follow your pre-operative diet – it can range from two to six weeks.
Starting the diet (T)
The amount of medication that you are taking for your diabetes when you start the pre-operative diet
may need to be reduced. If you are not sure how to make this adjustment please contact one of the
bariatric team on the number listed at the end of this leaflet.
Checking your blood sugar (T)
If you are on any medication other than Metformin when you start your diet you should regularly check
your blood sugar level. You should do this a minimum of twice a day, to make sure your blood sugars
are not too low.
Any reading below 4 mmol/L is considered to be a hypoglycaemic event, or ‘hypo’. If this happens you
should follow the instructions on the page 4 (Management of hypoglycaemia before and after surgery) to
treat yourself.
What medication should I take before surgery (T)?
We advise that no diabetes medication is taken on the morning of your surgery.
What happens after surgery (T)?
When you have had your surgery your blood sugars will be monitored regularly by the nursing staff while
you are in hospital. You will be advised before you leave hospital what medication you need to take
when you go home.
You will be given contact numbers for the clinical nurse specialists (CNSs) when you leave hospital. You
should call if you are having any problems. The main CNS telephone number is also listed at the end of
this leaflet.
Generally most patients will go home on Metformin unless you are intolerant to this. Occasionally some
patients will go home on insulin. If you go home on insulin you will be asked to check your blood sugar
level four times a day for 10 days after surgery. It is important that you record these results and bring
them with you to your first clinic appointment after your surgery.
If you do not have a blood sugar meter you should ask one of the nurses on the ward to provide you with
one. They will show you how to use it before you go home.
After you go home, it is important to contact us if your blood sugar level is frequently above 12 or below
4 mmol/L. We aim for your blood sugars to be 4-7 mmol/L before food and below 9 mmol/L two hours
after food.
It is important for you to understand that your diabetes will be improved following surgery but you will not
be cured. You should therefore continue with your eye, kidney and foot screening tests in the community
or hospital.
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Before surgery (for those who normally inject insulin (I))
As you normally inject insulin for your type 2 diabetes, you may need to see the bariatric diabetes
physician. You will also see the bariatric team before surgery, at your pre-assessment appointment (this
is the appointment after the group meeting). At your pre-assessment appointment you will be advised
about the non-diabetic medication you should take on the day of your surgery.
Your surgeon or dietitian will give you a diet sheet at your pre-assessment appointment providing
information on what you should eat before and after surgery. You will be told how long you need to
follow your pre-operative diet. The length of time you will need to follow this diet ranges from two to six
weeks.
Starting the diet (I)
When you start the diet we usually suggest reducing the amount of insulin that you are taking by ten per
cent to prevent your blood sugar becoming too low. The bariatric consultant endocrinologist or clinical
nurse specialist (CNS) will advise you on how to adjust your insulin. Your insulin may need to be
adjusted several times during the pre-operative diet period.
Checking your blood sugar (I)
You should check your blood sugar level before each insulin injection to make sure it is not too low. Any
reading below 4 mmol/L is considered to be a hypoglycaemic event, or ‘hypo’. If this happens you should
follow the instructions on page 4 (Management of hypoglycaemia before and after surgery) to treat
yourself. You may also need to reduce the amount of insulin/tablets that you are taking.
What medication should I take before surgery (I)?
We advise that no tablets for your diabetes are taken on the morning of your surgery. However, you may
need to take your long-acting insulin the night before your surgery – the bariatric physician or nurse will
advise you about this before you have your surgery.
What happens after surgery (I)?
When you have had your surgery you will be advised before your discharge what medication you need
to take when you go home. Usually the amount of insulin that you will be taking after surgery will be a
much smaller amount than you were on prior to surgery.
If you go home on insulin you will need to keep in touch with the CNS if your blood sugar control is
unstable. After you go home, it is important to contact us if your blood sugar level is frequently above 12
or below 4 mmol/L. We aim for your blood sugars to be 4-7 mmol/L before food and below 9 mmol/L two
hours after food. You will find the main CNS number at the end of this booklet.
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You will be asked to check your blood sugar level four times a day for 10 days after surgery. It is
important that you record these results and bring them with you to your first clinic appointment after your
surgery.
If you do not have a blood sugar meter you should ask one of the nurses on the ward to provide you with
one. They will show you how to use it before you go home.
Generally, most patients will go home on Metformin unless you are intolerant to this.
It is important for you to understand that your diabetes will be improved following surgery but you will not
be cured. You should therefore continue with your eye, kidney and foot screening tests in the community
or hospital.
Management of hypoglycaemia before and after surgery (all type 2
patients)
If your blood sugar falls below 4 mmol/L while you are on the diet (either before or after your surgery), it
is important that you treat it correctly. Please follow the instructions below. Further details regarding
liquid, purée and soft diets are all provided within the diet sheet you will be given at your
pre-assessment appointment.
Step 1
Take one of the following:





5-7 Dextrosol tablets or 4-5 Glucotabs (you can purchase these from most pharmacies or larger
supermarkets)
90–120 ml of ‘standard’ Ribena (not the ‘lighter’ (reduced sugar) version available)
1 bottle (60 ml) of Glucojuice (you can purchase this from most pharmacies)
150–200 ml of fruit juice (if you are taking a statin you should not have grapefruit juice)
3–4 heaped teaspoons of sugar dissolved in water
Wait for 10-15 minutes after you have taken one of the above then recheck your blood sugar. If it is still
below 4 mmol/L repeat step 1. Otherwise go to step 2.
Step 2
When your blood sugar is above 4 mmol/L and you are feeling better, consume one of the following
long-acting carbohydrates:



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if you are on a liquid diet you should drink 200 ml of milk, but sip this, taking no more than 100 ml
at a time (or you can make a banana smoothie with the milk, remembering that it needs to be
runny enough to go up a straw)
if you are on a purée diet use milk or yoghurt to mash up a banana to the right consistency
if you are on soft diet you can have one slice of bread or toast

if you are on a normal diet you can have a meal from the diet sheet - it must contain
carbohydrates, e.g. potatoes, pasta or rice
Please note: if you have chronic kidney disease you should not eat bananas because of the high
potassium content.
General information
After your surgery you will be sent appointments to be seen in clinic at the following intervals:

7-10 days after surgery

3 months after surgery

6 months after surgery

12 months after surgery
Two years after your surgery you will be contacted for a telephone consultation.
As you lose weight your medication may need to be reduced. Therefore, it is important that you monitor
your blood sugar regularly (at least twice a day). You should do this once before breakfast and either
before, or two hours after, another meal.
If you are unsure how to adjust your medication you can contact us between 08.00 and 16.00 on the
numbers below. You can also email us.
Who can I contact?
Bariatric CNSs (for medical information and advice): 020 3312 5689
Bariatric CNS email (for general enquiries and advice): [email protected]
Emergency telephone number (medical emergencies only): 07826 859 741
Dietitians (for information about the pre- and post-operative diet): 020 3312 5688
Dietitians email: [email protected]
Administration (for information on dates for surgery and general enquiries): 020 3312 6449
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How do I make a comment about my treatment?
We aim to provide the best possible service and staff will be happy to answer any questions you may
have. However, if your experience of our services does not meet your expectations and you would like to
speak to someone other than staff caring for you, please contact the patient advice and liaison service
(PALS) on 020 3133 0088 (for Hammersmith and Charing Cross hospitals), or 020 3312 7777 (for St
Mary’s Hospital). You can also email PALS at [email protected]. The PALS team is able to listen to
your concerns, suggestions or queries and is often able to help sort out problems on behalf of patients.
Alternatively, you may wish to express your concerns in writing to:
Chief Executive - Complaints
Imperial College Healthcare NHS Trust
Trust Headquarters
The Bays, South Wharf Road
London W2 1NY
Alternative formats
This leaflet can be provided on request in large print, as a sound recording, in Braille, or in alternative
languages. Please contact the communications team on 020 3312 5592.
Bariatrics
Published: March 2015
Review date: March 2018
Reference no: 2537v1
© Imperial College Healthcare NHS Trust
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