Patients who undergo major surgery face a 15-30% risk of serious adverse events, including a 1-5% mortality risk in the first month after surgery. For patients with diabetes, the risk is even greater, and it is often aggravated by complications associated with hyper- and hypoglycaemia. Complications, such as wound infections, cardiovascular, and neurological events, not only affect patients negatively, but it challenges health care systems due to prolonged length of stays and increased need of care post-discharge.

Several factors make it particularly difficult to establish glycaemic control and stable blood sugar in patients with diabetes. Patients' usual glucose-lowering medications are often paused, and fasting is required at least six hours prior to the operation. Surgery induces a post-surgical stress response that may include both stress-hyperglycaemia and reduced gastrointestinal function. Furthermore, a patient's usual symptoms of hyper- and hypoglycaemia may be altered due to the anaesthetics.

The existing guidelines on perioperative diabetic care include recommendations on treatment and glucose monitoring from the preoperative fasting period to the postoperative phase where oral intake of food and drinks can be resumed. Intravenous glucose-insulin infusions are used during preoperative fasting, intraoperatively and postoperatively until patients can resume oral intake of food and drinks. After this, subcutaneous insulin administrations following the sliding scale insulin regimen are administered to the patients to treat hyperglycaemia and supplemental glucose (perorally or intravenously) in case of hypoglycaemia. The blood sugar levels are monitored via point-of-care (POC) blood glucose tests every hour during glucose-insulin infusions and four to six times daily in the postoperative period.

In spite of these guidelines, prospective studies have shown that blood glucose levels are outside the normal range in 40-60% of the time following major surgery, and usually due to hyperglycaemia.

In this registry study, we investigated how guidelines for perioperative diabetes care were implemented in Danish hospitals from 2017-2023. The primary hypothesis was that, in the 20% of cases with detected hyperglycaemia, insufficient insulin was provided thus not following exiting guidelines.

Inclusion Criteria:

• Adults 18 years of age or older
• Type 1 or Type 2 diabetes mellitus requiring glucose-lowering medication
• Non-cardiac surgery lasting min. 1hour

Exclusion Criteria:

• Patients using insulin pump
• Planned surgery for pancreatectomy (complete or partial)

The population consists of patients living with diabetes mellitus requiring glucose-lowering medication who undergo surgery in the period from Janurary 1st, 2017 to Janurary 1st, 2023 across hospitals in two regions of Denmark - the Capital Region and the Zealand Region of Denmark .

There is not a plan to make IPD available.