Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
To the Editor: Dr Finney and colleagues1 reported that high blood glucose levels in critically
ill patients were associated with worsening of prognosis in a dose-response
fashion. However, because the study was not prospectively designed to assess
the effects of insulin administration, we question the authors' conclusion
that exogenous insulin is positively associated with mortality in the ICU.
The patients receiving higher doses of insulin to maintain glucose levels
could have been more severely ill and insulin resistant, and this selection
bias could have undersestimated any beneficial effects of exogenous insulin.
Moreover, patients receiving insulin are not comparable to those who did not
receive insulin; they would be expected to have a higher mortality had they
not been given insulin, perhaps equivalent to the group in the higher glucose
band. We are similarly unconvinced that insulin resistance did not play a
significant role, as insulin-resistant patients require higher insulin doses
than do insulin-sensitive patients to maintain a particular glucose level,
irrespective of the prevailing glucose level.
Garg R, Chaudhuri A, Dandona P. Exogenous Insulin and Hypoglycemia as Prognostic Factors in Critically Ill Patients. JAMA. 2004;291(5):558. doi:10.1001/jama.291.5.559-a