How To Achieve Optimal Perioperative Glycemic Control In Patients With Diabetes
- Volume 19 - Issue 12 - December 2006
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Various researchers have also demonstrated that good glucose control minimizes perioperative morbidity and mortality. The classic prospective randomized study Diabetes Mellitus Glucose Infusion in Acute Myocardial Infarction (DIGAMI) showed the long-term benefit and reduction in mortality from myocardial infarction due to tight glucose control with the use of initial intravenous insulin infusion.10 There have been several subsequent studies that have looked at the positive impact that insulin may have on improving operative outcomes, particularly with cardiothoracic surgery.11 The reason for improved survival was probably multifactorial and included improved glucose homeostasis and possible improved oxygenation of the tissues through insulin’s vasodilatory effects to skeletal muscle via increased production of nitric oxide in vascular endothelium.12,13 Hyperglycemia may also accentuate the risk of thrombotic complications.14
Finally, studies have shown that hyperglycemia has deleterious effects on essential wound healing events such as decreased chemotaxis, polymorphonuclear leukocyte mobilization and phagocytosis. When it comes to patients with diabetes, skin fibroblasts reportedly do not proliferate as well in a hyperglycemic milieu and this may impair wound closure.15,16,17
Indeed, there are a multitude of reasons to avoid hyperglycemia, even for short-term intervals. Therefore, it is probably not ideal to aim for higher glucose levels than outpatient goals due to the fear of perioperative hypoglycemia. However, future prospective, controlled, randomized studies are necessary for further evaluation of safe modalities to improve glycemic control in the perioperative period.
At Beth Israel Deaconess Medical Center (BIDMC), our relationship with the Joslin Diabetes Center allows for frequent collaboration and many of our glycemic control practices are a result of those interactions. As we noted previously, while clinicians utilize many approaches, this following protocol is the one we employ most frequently.
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.