How To Achieve Optimal Perioperative Glycemic Control In Patients With Diabetes
Key Considerations With Perioperative Glycemic Control
Regardless of the aforementioned factors, four primary glycemic goals remain paramount. These goals include: preventing hypoglycemia, preventing hyperglycemia, avoiding ketosis and reducing morbidity and mortality. The risks associated with hypoglycemia (defined as <60 mg/dL) are easily understood as hypoglycemia carries a significant risk of mortality. This state may trigger events such as cardiac arrhythmias or altered mental status, and it can be difficult to detect in the immediate postoperative period. Severe hyperglycemia may induce diabetic ketoacidotic (DKA) and hyperosmolar nonketotic states, as well as an increased potential for volume depletion secondary to osmotic diuresis. While those with type 2 diabetes are less likely to develop ketosis, patients with type 1 diabetes may progress to ketoacidosis without insulin. This becomes important when considering the management of elevated glucose in those with type 1 and type 2 diabetes, and each type carries different consequences. While a patient with type 2 diabetes can tolerate some mildly elevated plasma glucose values and still hold insulin dosing, this may prove catastrophic for type 1 diabetes patients, who may become ketotic as a result. Patients with type 2 diabetes are more prone to nonketotic states but may develop ketoacidosis at the extremely high range. Beyond these prime directives, the necessary stringency of glycemic control is unclear. The long-term benefits of tight glucose control are well documented in both diabetic types as evidenced by the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS).18,19 However, fewer reports address the perioperative period. Those that do consider this sensitive period generally are in reference to major surgical interventions and those in critical care units. Although tight glycemic control has shown promise in these patients with decreased morbidity and mortality, the applicability to less critically ill patients is poorly understood. If possible, one should schedule surgery early in the morning in order to avoid severe hypoglycemia and hyperglycemia, and most physicians aim to maintain a preoperative blood glucose level between 150 and 200 mg/dL. If the patient is actively receiving an insulin infusion, one can achieve tighter glucose control and the overall glucose goal becomes 101 to 150 mg/dL.20,21 At our institution, we divide patients into two groups when it comes to managing glucose. The first group includes all patients with type 1 diabetes or type 2 diabetes who require multiple daily insulin injections (sliding scales). The second group includes the remainder of patients who are not in the first group, namely those with type 2 diabetes who have a controlled diet, those taking oral hypoglycemics and those who take subcutaneous insulin once or twice daily. Regardless of which group a patient fits into, we strongly recommend surgery first thing in the morning, if at all possible, in order to avoid prolonged fasting.