FACT SHEET FOR PATIENTS AND FAMILIES
Blood Glucose Management Before Surgery
When you have diabetes, managing your blood glucose is
always important. But before you have surgery, it’s vital.
This sheet tells you why— and explains what you can do
Why is my blood glucose so
important right now?
Studies show that people with well controlled blood
glucose have fewer problems during and after surgery.
But unfortunately, staying in control might not be so
easy. Surgery can cause big problems in blood glucose
levels — even if you normally have things under control.
•• Surgery is stressful. Stress usually increases before,
during, and after surgery. Beforehand, you’re probably
a bit nervous. During and after surgery, your body is
stressed, trying to heal itself. And unfortunately, stress
makes your body release hormones that make it even
more difficult than usual to regulate blood glucose.
•• You may go off your normal meal plan. Often
your doctor will give you special instructions about
eating and drinking in the hours before surgery.
And for a few days after, you might not eat normally
either. Going off your meal plan can cause changes
in blood glucose levels.
•• Depending on what type you take, you may be
told to stop taking your diabetes medications
before surgery. Or you may need to switch to a
different medication, or adjust your dose.
If you have diabetes, prepare for a surgery by reading
this handout and following your doctor’s advice.
The stress and changes that surgery brings can push your
blood glucose too high — or too low. Very high or low
blood glucose can be dangerous at any time. But they’re
especially risky when they happen during or after surgery.
They can cause dangerous complications and slow your
recovery. So to avoid problems, feel better, and get
well faster — control your blood glucose.
What should I do to prepare for surgery?
Use this checklist to help make sure your blood glucose
stays in control before, during, and after your surgery.
Before you set a date for your surgery…
Visit the doctor who guides your diabetes treatment. Discuss
how to get your diabetes in the best possible control in the
weeks before your surgery. Can you fine-tune your treatment
plan? Should you adjust your insulin before surgery? Do you need
any special tests to check for possible problems during surgery?
Your doctor can answer these questions.
1 week before your surgery…
Test your blood glucose before each meal and at bedtime, if you
don’t already. Most people with diabetes should aim for these
• My pre-meal target: 70 to 130 mg/dL or
• My bedtime target: 100 to 140 mg/dL or
Follow your diabetes treatment plan faithfully. It’s more important
than ever right now.
1 day before your surgery…
Continue to test your blood glucose before each meal and at
bedtime — and write down the values. Your doctor may need to
refer to these readings.
Continue taking your oral diabetes medications. Take the same
pill(s) at the same time as usual, unless your doctor tells you not to.
Continue taking your insulin or other injectable medication as
usual, unless your doctor tells you otherwise.
Don’t eat or drink after midnight (12 AM). You can drink a few
sips of water if you’re thirsty.
The day of your surgery…
Adjust your insulin according to the box at right (or your doctor’s
Stop taking your other usual diabetes medications.
Check your blood glucose.
• If it’s low (less than 70 mg/dL), drink half a cup of clear soda
(regular, not diet) or clear juice (apple, cranberry, or grape —
not orange). Wait 15 minutes, then test again. If it’s still low
after two treatments, call the doctor who cares for your diabetes.
• If it’s high (more than 150 mg/dL), take a correction dose of
rapid-acting insulin. If you don’t have correction doses, call
your diabetes doctor.
if you take insulin...
If you take insulin, take your regular dose up until the night
before your surgery. On the day of surgery, you may
need to switch to a peakless (long-acting) insulin.
There are two types of peakless insulin, glargine (Lantus)
and detemir (Levemir).
The doctor who directs your diabetes treatment can give you
specific instructions for adjusting your insulin before surgery.
If you don’t receive specific instructions, follow
these general guidelines for making the switch on
the morning of surgery:
• If you already take peakless insulin (Lantus or
Levemir), take it as prescribed, including the morning
• If you use NPH insulin, replace it with peakless insulin
on the morning of surgery. The dose should be 80% of
the TOTAL amount of NPH you usually take in a day.
IF your usual daily dose of NPH is 40 units,
THEN INSTEAD take 32 units of peakless insulin
(Lantus or Levemir) on the morning of surgery.
•If you use 70/30 or 75/25 insulin, replace it with
peakless insulin on the morning of surgery. The dose
should be 60% of the TOTAL amount of 70/30 or 75/25
insulin you usually take in a day.
IF your usual daily dose of 70/30 or 75/25 is 50 units,
THEN INSTEAD take 30 units of peakless insulin
(Lantus or Levemir) on the morning of surgery.
•If you use an insulin pump:
–– Call your doctor before surgery to create a plan for
restarting your pump after taking peakless insulin.
–– On the morning of surgery, take a dose of peakless
insulin equal to the TOTAL amount of basal insulin
you usually take in a day.
–– One hour after you’ve taken the peakless insulin
dose, remove your pump.
–– Take rapid-acting insulin when you eat or to correct
a high blood glucose (use a syringe or pen).
–– Call your doctor or pharmacist if you have any
questions about adjusting your insulin.
When you go in for your surgery:
Instructions from my doctor:
Bring your written blood glucose records with you.
Report your last blood glucose reading to the doctor or nurse.
Remind the doctor or nurse what you’ve done about your
medications and your diet in the last few hours or days.
© 2011 Intermountain Healthcare. All rights reserved. The content presented here is for your information only. It is not a substitute for professional medical advice, and it
should not be used to diagnose of treat a health problem or disease. Please consult your health care provider if you have any questions or concerns. More health information is
available at intermountainhealthcare.org. Patient and Provider Publications 801.442.2963 fs282 - 12/11 Also available in Spanish.