Lower Blood Sugar in the ICU Good or Bad?

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According to the results of a new study, lowering blood glucose levels in ICU patients is found to increase mortality by 10%, in one of the largest studies to date. The authors suggest a review of current guidelines about how blood sugar levels are treated in critically ill patients is needed.

Lowering blood sugar levels in critically ill patients is a widely embraced practice. Critically ill patients often experience elevated blood sugar levels, and has been associated with complications that can lead to death from organ failure.

Chief Investigator, Professor Simon Finfer from The George Institute for International Health says, "Intensively lowering blood glucose in critically ill patients is not beneficial and may be harmful.“ The study, performed by researchers from multiple international groups was implemented to clarify a beneficial range of blood glucose levels in critically ill ICU patients.

To assess survival rates, the researchers followed 6104 critically ill ICU patients in Canada, New Zealand, the USA and Australia for ninety days, using a computerized algorithm. Their finding showed that intensive lowering of blood glucose level among ICU patients who are critically ill increased mortality, and there is an urgent need for revising current practices.

Chief Investigator Dr Dean Chittock of Vancouver Coastal Health and University of British Columbia, Vancouver, Canada says previous studies have been conflicting regarding whether tight blood sugar control is needed when managing critically ill patients. “This new study gives us more powerful information, based on this larger study with stronger evidence, we can conclude that targeting very low levels of blood glucose is not safe. Dr. Chittock adds, "It's essential that international guidelines reflect this new evidence. Many professional organizations recommend very tight glucose control for ICU patients – they will now need to take this new evidence into consideration and adjust recommendations accordingly."

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The NICE-SUGAR study results equated to one ICU death in 38 when blood sugars are kept lower in critically ill ICU patients.

Silvio E. Inzucchi, M.D., and Mark D. Siegel, M.D., of Yale University School of Medicine, wrote in an accompanying editorial, that "an almost linear relationship between blood glucose levels in hospitalized patients and adverse clinical outcomes, even in patients without established diabetes," has been seen in observational studies. In 2001, one such study suggested risk of dying could be decreased by 42% by tightly controlling blood sugar levels in the ICU. The study came from a single center in Leuven, Belgium.

The NICE-SUGAR study showed that hypoglycemia was common in critically ill patients associated with lowering blood sugars in the ICU – 829 deaths occurred among 3054 patients whose blood sugars were intensively lowered in the ICU versus 751 deaths among those whose blood sugars were not managed to lower levels.

The NICE-SUGAR study has its limitations. Ten percent of patients targeted to receive intensive blood sugar management dropped out of the study. Criteria used for the study was “expected length of stay”, a factor that may have placed influenced the study. Many of the ICU patients in the intensive glucose-lowering group were receiving steroids, another limitation.

Dr. Inzucchi and Dr. Siegel say the study leaves physicians who treat ICU patients “in something of a quandary”. They suggest that current practices remain in place for keeping blood sugar levels under tight control in the ICU until more studies are available, cautioning against any “ overreaction to the NICE-SUGAR findings”.

The study suggests that intensive lowering of blood sugar levels in critically ill patients may cause more harm than good, and increase mortality, but more answers are needed. Those answers "must await post hoc analyses that the NICE-SUGAR study investigators are now obliged to conduct, “ say the study editorialists. No one knows precisely why lowering blood sugar levels in critically ill ICU patients might lead to increased risk of dying.

Reference: NEJM

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