​​Diabetes mellitus is a chronic multi-system condition affecting 4.7% of Australian women and predicted to affect 5% of New Zealand women by the year 2044.^1,2 With over 600,000 gynaecological procedures performed annually in Australia and New Zealand combined, and 10% of all hospitalisations being associated with diabetes, it is a significant comorbidity for many women undergoing surgery.^3,4 Suboptimal management of diabetes is associated with perioperative dysglycaemia, increased surgical site infections, poor wound healing, and increased length of stay.^5,6 Thus, identification and referral of at-risk patients is crucial. Guideline-based perioperative management of patients with diabetes is ever evolving with the advent of new pharmacologic agents. Therefore, early involvement of anaesthesia and physician-led care is essential in keeping abreast of changes. ​​​ 

Primary care and surgical teams play an important role in screening for diabetes and the use of diabetes medication in the gynaecological surgical population.^5,7 Local and international guidelines differ slightly but advise referral to anaesthetics and physician-led intervention at an HbA1c > 8-9% (64-69mmol/L), especially for those with end-organ complications, or if patients are on a continuous subcutaneous insulin infusion (CSII) pump.^5,6,7 Ensuring a HbA1c test has been performed in the preceding three months, taking a brief history of diabetes type, medication history, and related micro- and macrovascular complications are useful when referring for further workup.^5,6,7 Perioperative care of the patient with diabetes is also governed by the principles of anticipating and treating perioperative dysglycaemia and minimising fasting time.^5,6,7 Dysglycaemia can be expected due to fasting and diabetic medications causing potential hypoglycaemia, and surgical stress causing hyperglycaemia.^5,6 Vigilance for this in all patients with diabetes is important and involves hourly finger-prick capillary blood glucose level (BGL) and ketone level monitoring while fasted (or every two hours if diabetes is well controlled by metformin monotherapy to a HbA1c target of <7%).⁷ Perioperative staff should also have training to escalate care and treat dysglycaemia via protocols appropriate to the pattern of dysglycaemia.^5,6,7 Minimising fasting times can be achieved by aiming for ambulatory surgery and prioritising patients with diabetes first on operative lists where possible.⁵  

There are multiple classes of non-insulin antihyperglycaemic agents used to treat diabetes. In general, these agents should be continued up until the night before surgery and omitted on the day of surgery.⁷ However, all patients (including patients without diabetes) must be screened for newer agents such as sodium-glucose co-transporter channel 2 inhibitors (SGLT2i) and glucagon-like peptide receptor agonists (GLP-1 RAs) as these can have significant metabolic and anaesthetic complications and are increasingly prescribed for non-diabetic indications. SGLT2i can cause euglycaemic diabetic ketoacidosis (euDKA), especially in the context of prolonged perioperative fasting.^7,8 SGLT2i need to be discontinued 72 hours pre-procedurally, that is, the morning of the procedure and the two preceding preoperative days.^7,8 Despite being appropriately withheld, patients may still experience euglycaemic ketosis/ketoacidosis perioperatively. Patients can be asymptomatic or symptomatic with nausea, abdominal pain, and vomiting, but confirmatory findings are capillary ketone levels >1.0mmol/L or base excess < -5mmol/L on a venous or arterial blood gas, in keeping with metabolic acidosis.8 Patients meeting the above treatment threshold should be considered for intravenous glucose and/or insulin therapy. SGLT2i can be recommenced postoperatively once the patient has fully returned to normal enteral intake.⁶    

GLP-1 RAs, or injectable weight loss drugs such as Ozempic^TM, represent a growing perioperative challenge, particularly due to increasing off-label use in the general population. These drugs delay gastric emptying to increase satiety, decrease caloric intake, and improve glycaemic control, resulting in increased risk of perioperative aspiration of residual gastric contents if prolonged fasting instructions are not adhered to.⁷ Aspiration has previously been the leading cause of mortality in Australia and New Zealand under anaesthesia prior to the advent of GLP-1 RAs.⁹ Patients now risk having their elective procedures cancelled if they have not performed a 24-hour clear oral fluid diet followed by strictly six hours nil by mouth while receiving these medications.¹⁰ Importantly, current recommendations support continuation of GLP-1 RAs perioperatively independent of indication, highlighting the importance of prolonged fasting to improve perioperative safety.¹⁰ Anaesthetic risk mitigation strategies to decrease aspiration rates if patients have not withheld solids for 24 hours include the performance of point-of-care gastric ultrasound (POGUS) to quantify residual gastric contents, administration of prokinetic agents, modification of anaesthesia, or deferring the procedure.¹⁰  

Patients requiring insulin should continue to take their regular insulin up to and including the night before the procedure, except if bowel preparation is required, which may be relevant for more complex gynaecological or joint colorectal procedures.⁷ As aforementioned, patients receiving insulin therapy warrant an endocrinology and anaesthetics referral to assist with perioperative management and glycaemic control, or for consideration of preoperative admission for variable-rate insulin infusion (VRII) therapy.^5,6,7 This helps to ensure that patients receive personalised instructions, especially regarding relevant dose reductions to premixed (rapid and intermediate-acting) or co-formulated (rapid and ultra-long acting) insulins. Patients may instead be on a basal/bolus regime, in which case they should continue all basal doses (long-acting “background” insulin) at regular times as long as they have not experienced recent hypoglycaemia at these doses.⁷ Rapid-acting insulin boluses should be omitted during fasting, and can be recommenced once the patient has returned to at least 50% of their usual enteral intake, ideally with endocrinology oversight as additional correction boluses may be required.⁷ Patients receiving CSII via a pump should either switch to exercise mode, continue their basal insulin or decrease to 80% of their basal dose if fasting BGL <5mmol/L.⁷  It is important to note that continuous glucose monitors (CGM) are not recommended for use intraoperatively and immediately post-operatively when the patient is unable to interpret the readings. Therefore, medical staff should check hourly capillary BGLs and ketones until the patient is able to resume self-monitoring. ¹¹ Care must also be taken regarding the proximity of the insulin pump to the surgical site and the CGM position relative to equipment such as blood pressure cuffs or tourniquets. Patients may need to be advised pre-admission to ensure their device and CGM are appropriately positioned to minimise wastage of consumables.   

In summary, diabetes represents a significant burden of disease in Australia and New Zealand, with pharmacotherapy continually evolving and contributing new challenges to perioperative management.  

Patients living with diabetes benefit from a multidisciplinary team approach including GPs, surgeons, endocrinology, anaesthetics, and nursing staff, and require increased perioperative vigilance to maintain patient safety. 

Clinicians are reminded to consult relevant hospital guidelines and national joint statements for guidance on fasting times for patients on GLP-1 RAs, withhold SGLT2i for day of surgery and two days prior to decrease the risk of perioperative euglycaemic ketoacidosis, and seek endocrinology and anaesthetics input for patients receiving insulin therapy.  

Table 1: Key points for clinicians