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Perioperatively, insulin to treat hyperglycemia is administered judiciously to minimize the risk of hypoglycemia. In patients with diabetes in whom preoperative blood glucose levels are on the low end of normal, hypoglycemia risk may be underestimated. This retrospective study enrolled subjects with presenting preoperative blood glucose values in these ranges: 70 to 89 mg/dL (low normal group) and above 249 mg/dL (hyperglycemia-treated group). These groups were compared for subsequent perioperative hypoglycemia development.
Subjects in the low normal group (n = 308) were older (P < .001), had increased incidence of renal disease (P = .02), and more prevalent â-blocker use (P = .02) than the hyperglycemia-treated subjects (n = 279). Accounting for differences between groups, the incidence of perioperative blood glucose levels below 70 mg/dL was greater in the low normal group than the hyperglycemia-treated group (17.2% vs 3.6%, P < .001). Of subjects whose blood glucose levels fell below 70 mg/dL, blood glucose levels dropped below 50 mg/dL in 40% of hyperglycemia-treated subjects and 4% of low normal subjects.
Perioperative hypoglycemia was likelier to develop in patients with diabetes who presented preoperatively with low normal blood glucose values than in patients treated with insulin for presenting hyperglycemia.
Keywords: Diabetes, glycemic, hypoglycemia, perioperative.
The perioperative management of glycemic control in patients with diabetes is challenging. Signs and symptoms alerting hypoglycemia are obscured in anesthetized patients. To avoid hypoglycemia during pre-procedural fasting, a downward adjustment in dose or omission of usual glucose-lowering medications is often advocated.1,2 Surgical stress, however, has been associated with increased glucagon and decreased insulin response.3 Although the mechanisms are unclear, isoflurane and sevoflurane for anesthesia have been associated with suppressed endogenous insulin secretion and prolonged plasma glucose disappearance.4 Insulin sensitivity varies among individuals. 5 For these reasons, the glucose-lowering effect of exogenous insulin is difficult to predict.
There is substantial evidence linking inpatient hyperglycemia with greater morbidity and mortality.6-9 Low glucose values have also been associated with increased hospital costs, higher likelihood of discharge to a skilled nursing facility, increased length of stay, and greater mortality. 10,11 Severe hypoglycemia may contribute to, increase vulnerability to, or be a marker of poor outcomes.12,13 During continuous glucose monitoring, cardiac ischemia has been detected more frequently during hypoglycemia than either normoglycemia or hyperglycemia.14...