The history and type of DM are important factors to consider when devising a perioperative management plan. Patients with noninsulin-dependent diabetes (type 2) whose condition is controlled with oral hypoglycemic agents or diet are best treated with intravenous ﬂuids containing no dextrose and should not be given insulin intraoperatively. Oral administration of hypoglycemic agents should be discontinued when the patient ceases oral intake of food, and hyperglycemic episodes in the perioperative period are treated with sliding-scale regular insulin if blood sugar levels exceed 200 mg/dL (151,153).
Insulin-dependent or type 1 diabetes poses a more difficult problem. These patients are insulin deficient and therefore require a basal rate of insulin at all times. Likewise, they require a baseline intake of glucose. They risk developing diabetic ketoacidosis whether or not they are eating (153). Preoperatively, the goals include avoiding ketoacidosis and hypoglycemia, and, to a lesser extent, hyperglycemia. Traditionally, approximately one-third to one-half of the patient’s usual daily dose of NPH insulin (intermediate acting) is given subcutaneously the morning of surgery. Omit any short-acting insulin without oral intake. An infusion of 5% dextrose should be given while being restricted from oral intake. Additional regular insulin can be administered in the operating room as needed (150,153). If patients are normally on a continuous insulin infusion, they may continue at their usual infusion rate. There is no single regimen that is superior for the intraoperative management of type 1 diabetic patients. A continuous intravenous insulin infusion is indicated for patients with unstable type 1 diabetes, those who require emergency surgery while in ketoacidosis, and those undergoing long, complex procedures (161). Consultation with endocrine and anesthesia colleagues can be helpful in managing these complex regimens.
Postoperative Management Postoperative monitoring of patients with DM includes careful monitoring of serum glucose levels. If an intravenous insulin regimen is used, blood glucose levels must be checked every 1 to 2 hours. If a sliding-scale insulin administration is used, blood glucose should be checked and documented approximately every 6 hours until the patient is eating and stable on her preoperative regimen. The serum glucose level should be maintained at less than 250 mg/dL, and ideally below 140 mg/dL when fasting and below 180 mg/dL with random draws (165,166). For type 2 diabetics, oral hypoglycemics can be restarted when the patient resumes eating, except with metformin, which requires normal renal and liver function (153).
It is essential to prevent the development of severe hypoglycemia or hyperglycemia and the associated complications of diabetic ketoacidosis or a hyperosmolar state. Rigorous perioperative management may obviate some of the infectious and wound-healing complications that are more common in these patients (167).
Thyroid Syndromes Thyroid dysfunction should be suspected in any patient with a history of hyperthyroidism, use of thyroid replacement medication or antithyroid medication, prior thyroid surgery, or radioactive iodine therapy.