The most challenging issue in diabetic patients is the maintenance of glucose control during the perioperative period. The increased secretion of cortisol, epinephrine, glucagon, and growth hormone during surgery is associated with insulin resistance and hyperglycemia in diabetic patients. The goal of management is the prevention of severe hyperglycemia or hypoglycemia in the perioperative period.
Poor preoperative glycemic control, as indicated by an elevated hemoglobin A1c level, is associated with a greater risk of surgical complications, particularly infections. However, a strategy of delaying surgery until glycemic control improves has not been rigorously studied. The ideal postoperative blood glucose target is also unknown. Trials have demonstrated that tighter perioperative glycemic control leads to better clinical outcomes in cardiac surgery patients in a critical care unit. This finding is not generally applicable to other surgical patients, however, since a subsequent trial demonstrated increased mortality with tight control in surgical patients in an intensive care unit. Data are lacking on risks and benefits of tight control in patients outside of intensive care units. Based on trials that showed increased mortality in hospitalized patients randomized to tight control, the American College of Physicians recommends maintaining serum glucose between 140 mg/dL and 200 mg/dL (7.8–11.1 mmol/L), whereas the British National Health Service guidelines recommend a range of 108–180 mg/dL (6–10 mmol/L). Even for coronary artery bypass patients, the Society of Thoracic Surgeons recommends a blood glucose range of 121–180 mg/dL (6.7–10 mmol/L).
The specific pharmacologic management of diabetes during the perioperative period depends on the type of diabetes (insulin-dependent or not), the level of glycemic control, and the type and length of surgery. Oral hypoglycemic agents should be held on the day of surgery. They should not be restarted after surgery until oral intake is adequate and unlikely to be interrupted. For patients taking insulin, a common practice is to reduce the last preoperative dose of long-acting, basal insulin by 30–50% and hold short-acting nutritional insulin (Table 27–11). Use of correctional insulin only (without basal or nutritional insulin after surgery) is discouraged. A trial comparing correctional insulin with basal-bolus dosing found that the latter strategy led to fewer postoperative complications. Most patients with type 1 diabetes and some with type 2 diabetes will need an intravenous insulin infusion perioperatively. Consultation with an endocrinologist should be strongly considered when patients with type 1 diabetes mellitus undergo major surgery (also see Diabetes Management in the Hospital, Chapter 27-01). All diabetic patients require frequent blood glucose monitoring to prevent hypoglycemia and to ensure prompt treatment of hyperglycemia. Perioperative use of corticosteroids, common in neurosurgical and organ transplant procedures, increases glucose intolerance. Patients receiving corticosteroids often require additional short-acting insulin with meals, while their fasting glucose levels and basal insulin requirements may remain relatively unchanged.
Hypotension or shock resulting from primary or secondary adrenocortical insufficiency is rare. The common practice of ...