In
a randomized trial published in 2001, Van den Berghe and colleagues
demonstrated that intensive insulin therapy lowered mortality among
hyperglycemic surgical intensive care unit patients, most of whom had
undergone cardiac surgery. Those results prompted some authorities to
advocate intensive insulin therapy for all hyperglycemic ICU
patients. In two new retrospective observational studies, researchers
have explored the relation between hyperglycemia and ICU mortality.
During
a 5-year period, a protocol for glycemic management was instituted in
a multidisciplinary ICU in Arizona; the goal was to keep glucose
levels lower than 150 mg/dL. Of 7285 patients, 61% had normal glucose
levels (controls), 24% required insulin but had no history of
diabetes, and 15% were known to have diabetes. Diabetic patients had
a higher mean glucose level and received more insulin than did
nondiabetic hyperglycemic patients; nevertheless, at admission and
during hospitalization, nondiabetic hyperglycemic patients were
sicker than diabetic patients and controls, and had higher mortality
rates (10% vs. 6% and 5%, respectively).
In
a study from a Maryland ICU, researchers compared mortality rates
among 743 patients who were hyperglycemic (glucose levels >200 mg/dL)
at admission with rates among 1970 patients who were normoglycemic.
Among patients with previously detected diabetes, hyperglycemia on
admission was not associated with mortality. In contrast, among
nondiabetic patients, hyperglycemia on admission independently
predicted mortality. However, this association was noted in the
cardiac, cardiothoracic, and neurosurgical ICUs, but not in the
general medical and surgical ICUs.
These
studies illustrate the complexity of the associations between
hyperglycemia and mortality in heterogeneous ICU populations. Hyperglycemia
appeared to be an important risk factor for mortality mainly among
people without previously recognized diabetes. Moreover, the
prognostic importance of hyperglycemia might vary, depending on the
particular type of ICU. Because of these complexities, two sets of
editorialists do not believe that the 2001 Van den Berghe results
justify intensive insulin therapy for all hyperglycemic ICU patients.
Fortunately, two clinical trials are being conducted to settle this
controversy — NICE-SUGAR and Glucontrol.
Reference:
1.
Rady MY et al. Influence of individual characteristics on outcome of glycemic
control in intensive care unit patients with or without diabetes mellitus. Mayo
Clin Proc 2005 Dec; 80:1558-67.
2.
Whitcomb BW et al. Impact of admission hyperglycemia on hospital mortality in
various intensive care unit populations. Crit Care Med 2005 Dec;
33:2772-7.
3.
Bellomo R and Egi M. Glycemic control in the intensive care unit: Why we
should wait for NICE-SUGAR. Mayo Clin Proc 2005 Dec; 80:1546-8.
4. Angus DC and Abraham E. Intensive insulin therapy in critical illness: When is the evidence enough? Am J Respir Crit Care Med 2005 Dec 1; 172:1358-9.