How To Achieve Optimal Perioperative Glycemic Control In Patients With Diabetes
As the role of the podiatric service becomes more integral to a multidisciplinary approach to diabetic limb salvage at an increasing number of institutions nationwide, many podiatric surgeons find themselves admitting these patients to their own service. The surgical and anesthesia teams often execute perioperative assessment and preparation, especially in non-elective procedures.
This article serves as a primer in glucose management for podiatric surgeons working in this capacity and in no way supersedes the utility of a medical consult when indicated. Evaluation and assessment of other common comorbidities such as the cardiovascular and renal function are also equally important in the preoperative examination and determination of the overall optimization of a patient.
What The Research Reveals About Metabolic Changes Due To Surgery
Currently, there is no universal perioperative protocol for glycemic control. This is largely due to the variety of available treatment regimens and the degree of customization required to optimize the patient.1,2 Patients respond differently to insulin and other hypoglycemic medications based upon many confounding factors, such as the type of diabetes, level of insulin resistance, overall metabolism and the stresses placed upon the body among other factors.
A complex metabolic process ensues in response to surgery and anesthesia. Briefly, insulin resistance develops from increased secretion of varying amounts of the counter-regulatory hormones glucagon, epinephrine, norepinephrine, cortisol and the growth hormone produced during times of stress. There is also an overall decreased amount of insulin secretion due to increased sympathetic response and general anesthesia. This insulin resistance causes further hepatic glucose production and decreased peripheral glucose utilization.3,4,5
Furthermore, the type of anesthesia used and extent of surgical intervention undertaken creates large variations in these counter-regulatory hormones, making glucose homeostasis difficult to predict and highly variable. This catabolic fasting state of gluconeogenesis, glycogenolysis, ketosis, proteolysis and even lipolysis places the diabetic patient at risk for developing severe hyperglycemia and even potentially ketoacidosis if he or she has type 1 diabetes.6
Emphasizing The Importance Of Tighter Glycemic Control
Even though glycemic control seems to be of obvious importance in the perioperative period, the saying “better sweet than sour” is still a frequent consensus. The reasons to maintain an inpatient’s blood glucose levels somewhat higher than normal in preparation for surgery are often multifactorial. However, recent literature has been rife with data regarding tighter control of glucose in the perioperative setting.
Although the exact mechanism is not fully understood, researchers have shown in multiple publications that hyperglycemia, especially blood glucose levels greater than 200 mg/dL, increases the risk of developing postoperative infections.7,8 A recent article by Hruska, et. al., clearly showed that instituting a strict blood glucose level between 120 and 160 mg/dL immediately following open heart surgery resulted in a statistically significant decrease in postoperative infection rates in their diabetic patients. After patients maintained well controlled blood glucose levels through an insulin infusion, researchers found that the infection rate diminished from 73 percent to 25 percent in their diabetic population.9