How does DM affect perioperative morbidity and mortality?
Early reports suggested that patients with DM have an increased risk for perioperative morbidity and mortality. Subsequent epidemiologic studies that segregated groups according to end-organ damage showed limited differences between diabetic and nondiabetic patients. In evaluating a diabetic patient, the focus should be on the end-organ dys-function, which will influence the patient’s perioperative course in addition to the degree of glycemic control. End-organ damage is probably responsible for the fivefold increase in perioperative mortality associated with DM.
Perioperative hyperglycemia increases mortality and major morbidity, such as renal failure and sepsis. This increased risk occurs even in patients not known to be diabetic, and is reduced by tight glucose control in the operating room and in the intensive care unit (ICU). Most of the intraoperative data come from the cardiac surgery population.
Healing of deep wounds that require collagen synthesis for healing is impaired by hyperglycemia. Purely epithelial wounds appear to heal well regardless of blood glucose levels. Diabetics have an increased incidence of infectious complications.
The relationship of blood glucose levels to neurologic recovery is the subject of ongoing research. The majority of available evidence supports a deleterious effect of hyper-glycemia on neurologic recovery. Hyperglycemia appears to adversely affect recovery following global but not focal cerebral ischemia. Patients with diabetic autonomic neuropathy have a high incidence of both gastroparesis and painless myocardial ischemia. Gastroparesis is associated with an increased risk of aspiration; therefore, preoperative treatment with metoclopramide may be useful.
Responses to hypoxia may be impaired by autonomic neuropathy. Responses to the respiratory depressant effects of drugs may be accentuated. There is one report of the diabetic stiff joint syndrome leading to difficulty in endo-tracheal intubation. DM is associated with small-vessel problems such as coronary artery, cerebrovascular, and renal diseases.