Surgery and diabetes
Going into hospital for surgery can fill anyone with anxiety – doesn’t matter if it’s major abdominal surgery, a broken bone or a short diagnostic procedure – it’s all “scary”! Even more so for people with diabetes as there are so many unanswered questions. Will they check my glucose levels? Will I go low? What happens if I can’t eat after the operation? Should I decrease my insulin, stop my tablets or just eat less?
Although every case is different depending on what surgery, what type of diabetes, what medication and a host of other variables, there are some basic guidelines that may reduce anxiety and make for a better surgical experience.
Why does surgery cause stress in diabetes?
The peri-operative period (time surrounding and including the operation) is often associated with a decline in glucose control due to a combination of factors including the stress response of surgery, starvation, tissue damage during surgery and pain. These all lead to an increase in pro-inflammatory response mediators and stress hormone release. This, in turn, change insulin sensitivity and secretion resulting in a state of relative insulin resistance and breakdown of proteins and fats in the body. This may last for a few hours or extend into a few days after surgery all of which has a negative effect on the length of hospital stay and post-operative complications including infection and major organ damage.
So here are some basic tips to ensure during the peri-operative period:
- Rethink elective surgery (that which is not immediately necessarily) if your HbA1c is >8.5%
- Aim to keep blood glucose levels between 6.0-10.0mmol/l
- Speak to your diabetologist prior to surgery to help you manage your levels as well as possible
- Using a sliding scale of insulin in hospital is NOT recommended
- Aim to minimise the period of starvation as much as possible (plan surgery for early in the morning rather than later in the day)
- Those people who have additional risk factors (kidney disease, heart disease, lung dysfunction etc) should seek expert advice during the PLANNING phase of surgery
- Involve a team of healthcare professionals including your diabetologist, surgeon, anaesthetist and post-op rehab team to attain the best possible outcome
Some medications need to be reduced or completely omitted. Some of the newer oral agents don’t really have good data to guide us so individual advice may be required. Insulin requires more careful adjustment and you should seek specific advice from your doctor prior to surgery. Generally an evening dose of basal insulin should be reduced by 20% the day before surgery and restarted after surgery. Pre-mix insulin can be given as usual the night before and then reduced to 50% on the morning of the surgery, reducing with dinner. Those people using a basal-bolus regimen should reduced the night-time basal dose by 20% as above and omit bolus doses whilst fasting.
Hypoglycaemia (low blood glucose levels) is a serious risk in the peri-operative period. A reading of <6.0mmol/l should indicate imminent hypoglycaemia whilst a level <4.0mmol/l requires immediate treatment in order to prevent adverse complications. Hospitals can give intravenous dextrose if the blood glucose levels are low and continuous testing should continue every 15mins until levels return to normal.
Hyperglycaemia is not an acceptable complication of surgery however it may well be expected! Post-operative stress, infection and tissue trauma may well result in high glucose readings for some time after an operation. Consult your diabetologist and ensure you know how to manage your glucose levels during this period. Higher than normal levels will place you at an increased risk of post-operative complications such as infection, delayed healing or even a stroke or heart attack.
Those people who use insulin pumps should usually be encouraged to manage their own glycaemic control as much as possible. However, it is necessary to inform the surgeon and anaesthetist that you are using a pump and ensure they are familiar with your exact device. Remember, there are quite a few pumps in use and unless you are dealing with each device on a regular basis, individual settings and management may be difficult for someone who is unfamiliar with them. Make sure you et a print out of your daily settings from your diabetologist prior to surgery and give this vital information to the anaesthetist before your surgery.
No single solution will be adequate for every patient in every situation so it is very important to consult your multi-disciplinary team prior to surgery. Your diabetologist can give vital information to your surgeon and anaesthetist on how your diabetes is managed. Post-operatively, the surgeon can inform your diabetologist of complications expected linked to the surgery and you can then titrate your medication accordingly. The post-op rehab team including physiotherapists, occupational therapists and perhaps even psychologist will also need to interact with your usual health care team to ensure the best possible outcomes.
As with most things in diabetes, planning and being prepared is your best defence so communicate with the team and ensure the best possible outcome from your surgery.