Correspondence  |   November 2017
Insulin for Perioperative Glucose Control: Settled Science?
Author Notes
  • University of Chicago, Chicago, Illinois (A.T.). atung@dacc.uchicago.edu
  • (Accepted for publication July 26, 2017.)
    (Accepted for publication July 26, 2017.)×
Article Information
Correspondence
Correspondence   |   November 2017
Insulin for Perioperative Glucose Control: Settled Science?
Anesthesiology 11 2017, Vol.127, 899-900. doi:10.1097/ALN.0000000000001845
Anesthesiology 11 2017, Vol.127, 899-900. doi:10.1097/ALN.0000000000001845
We read with interest the recent Clinical Concepts and Commentary article on perioperative glucose control.1  However, we worry that it overstates available evidence with respect to the benefit/risk ratio of using insulin to target specific intraoperative glucose levels in patients undergoing surgery.
The authors rightly note that most studies find a strong correlation between hyperglycemia and poor perioperative outcomes in cardiac and noncardiac surgery.2  However, they do not mention that this correlation may not be as tight in diabetic patients3  who are most likely to experience perioperative hyperglycemia. Although the mechanism for this variability is incompletely understood, one possibility is that poorly controlled diabetics “reset” their hypoglycemic response to a higher glucose threshold.4  A uniform target for glucose management thus ignores that, for some patient groups, aggressively targeting a single value may cause harm both chronically5  and in the perioperative period.6  Existing intensive care unit studies clearly demonstrate that overly tight glucose control can increase mortality so the risk/benefit of any specific glucose target should be empirically tested to permit the clinician to deliver optimal care. Studies of the 200 mg/dl threshold used in the Surgical Care Improvement Project Infection-4 metric find no benefit to Infection-4 compliance,7  indicating that 200 may not be the right number. More recent data further complicate benefit/risk balance, observing that although mixed perioperative hyperglycemia and hypoglycemia worsened mortality after cardiac surgery, hyperglycemia alone (more than 180 mg/dl) had no effect.6 
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