Perioperative Continuation of Metformin Therapy in Patients With Typ 2 Diabetes Mellitus Undergoing Non-cardiac Surgery

Perioperative Continuation of Metformin Therapy in Patients With Typ 2 Diabetes Mellitus Undergoing Non-cardiac Surgery

Perioperative Continuation of Metformin Therapy in Patients With Typ 2 Diabetes Mellitus Undergoing Non-cardiac Surgery

Evaluation of the effect of peri-operative continuation of oral metformin therapy on the incidence of perioperative hyperglycemia compared to standard preoperative cessation of oral metformin therapy 24h before surgery.

Surgical procedures cause metabolic stress and can impair glucose control especially in patients with diabetes mellitus, which often results in peri-operative hyperglycemia. Peri-operative hyperglycemia is associated with impaired wound healing, secondary wound infections, endothelial dysfunction, sepsis, prolonged hospital stay and higher mortality. Metformin is still the first line treatment in patients with type 2 diabetes mellitus. Historically it has been stopped before surgery due to fear of hypoglycemia and metformin induced lactic acidosis. However recent studies have suggested that perioperative continuation of metformin might be safe and patients could benefit from more stable preoperative blood sugar levels. Prospective studies evaluating the benefit of continuing oral metformin therapy in the perioperative period are rare. The investigators plan to conduct a prospective, randomized-controlled, unblinded clinical trial where patients with type II diabetes mellitus and oral metformin therapy undergoing non-cardiac surgery will be randomized in either an interventional group or a control group. In the interventional group patients will be instructed to continue their regular metformin dose even on the day of surgery, in contrast to the control group, where the patients will be instructed to stop taking metformin 24h prior to surgery. All other oral anti-diabetic drugs will be paused according to the local anesthesia guidelines. The investigators plan to evaluate whether or not continuation of metformin can reduce the incidence of perioperative hyperglycemia and whether or not it is associated with elevation of blood lactate levels.

The study intervention involves the self-administration of metformin in the same dosage as the patient's regular dosage according to regular dosing schedule and randomization.

The control group involves no intervention, which means cessation of oral metformin therapy 24 hours prior to surgery according to the local guidelines of the anesthesia department and the national anesthesiology guidelines.

Perioperative continuation of oral metformin therapy according to the patient's normal dosage and dosage intervals

blood glucose >180mg/dl (10mmol/l) and/or necessity of additive administration of insulin s.c. during the time frame

blood lactate values >4mmol/L at least at one of 4 measurement dates: 24h pre-op, intra-op, 2 hours post-op, 24 hours post-op

Inclusion Criteria: Age 18-99 years Diabetes Mellitus Typ 2 Oral metformin therapy Non cardiac-surgery Informed consent Exclusion Criteria: Insulin therapy Ambulatory surgery Preoperative therapy with glucocorticoids (prednisolon or equivalent ≥ 5mg/day for more than 7 days) Planned postoperative ICU-stay Advanced renal insufficiency (eGFR < 45ml/kg/min) Advanced liver cirrhosis or failure (Child-Pugh B or C) Alcohol abuse Pregnancy, Perioperative administration of contrast dye

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