What is the optimal range of glucose control in IV insulin therapy?

Updated: Nov 06, 2018
  • Author: Guy W Soo Hoo, MD, MPH; Chief Editor: George T Griffing, MD  more...
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The results of the experience with intravenous insulin and tight glucose control had led to a re-examination of the optimal range of glucose control. Although control of hyperglycemia did reduce infection rates, especially after cardiothoracic surgery, a net benefit was tempered by higher rates of hypoglycemia and mortality. The ideal target blood glucose level in the intensive care setting has yet to be established but seems to be less than 180 mg/dL (< 10 mmol/L).

The lowest acceptable threshold for serum glucose has not been established. However, given the increased risk of hypoglycemia associated with insulin protocols that sought to control blood glucose levels between 80-110 mg/dL, a goal of less than 110 mg/dL cannot be endorsed. This was also the sentiment of a consensus statement that suggested a glucose target of 140-180 mg/dL in critically ill patients; however, certain subgroups, such as patients undergoing cardiothoracic surgery, may benefit from a lower target range. [7] Therefore, a glucose target of 110-140 mg/dL may eventually be a more appropriate range for this subgroup and other critically ill patients; however, this level of control has not been subjected to rigorous investigation and determined with evidence-based support.

The Society of Thoracic Surgeons examined the evidence for intravenous insulin; although they endorsed the use of intravenous insulin therapy in patients undergoing cardiac surgery, they did not endorse a strict glucose target range. They cite evidence that supports a target glucose of less than 180 mg/dL using intravenous insulin for at least the first 24 hours postoperatively, with a target of less than 150 mg/dL if their ICU stay exceeds 3 days because of comorbidities requiring mechanical ventilation, inotropes, ventricular-assist devices, intra-aortic balloon pumps, antiarrhythmics, or renal replacement therapy. [6]

In summary, the optimal range of glucose control in critically ill patients remains to be determined. A glucose control target between 140-180 mg/dL is recommended in most critically ill patients. Those with a higher severity of disease may benefit from control that aims for the upper threshold to be less than 150 mg/dL. The burden of experience and risk of hypoglycemic complications no longer supports to further reduce glucose levels below 110 mg/dL.

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