Diabetes mellitus is increasingly prevalent and
associated with signifi cant end organ damage that one
may presume to impact upon critical illness. However,
Siegelaar and colleagues present data that suggest,
excepting those patients admitted to a cardiac
intensive care unit, the presence of diabetes mellitus is
not associated with increased mortality in critically ill
patients. It is not possible to unpick how unmeasured
parameters such as glycaemic control, the nature of
whether type I or type II, or concomitant drug therapy
confound the results. Nevertheless, the results are
consistent with many risk-adjustment models used
in the critically ill, and clinical practice that tolerates
mild hyperglycaemia. Is it even possible that diabetes
mellitus is protective?