In a retrospective study, Dr Mikhail Kosiborod (Mid America Heart Institute, Kansas City, MO) and colleagues found that low blood glucose per se is likely not a direct cause of death in hyperglycemic acute myocardial infarction (AMI) patients, but rather points to a sicker patient population. They demonstrated that while hypoglycemia is indeed associated with increased mortality, this risk was restricted to patients who developed hypoglycemia spontaneously, and not those treated with insulin. The study used data from Health Facts, pooling data on AMI patients hospitalized between January 1, 2000 and December 31, 2005. In all, 7820 patients with hyperglycemia on admission were analyzed according to whether they developed hypoglycemia during their hospital stay and, in turn, whether glucose drop occurred in conjunction with insulin treatment or spontaneously. Kosiborod et al report that mortality rates were significantly increased in patients who developed hypoglycemia as compared with patients who did not, but not among patients treated with insulin. In multivariate analyses, hypoglycemia emerged as a predictor of mortality among patients who did not receive insulin, but not in those who did. They conclude that hypoglycemia during hospital stay is likely a marker for critical illness--things like shock, concomitant sepsis or liver failure, or multisystem organ failure--rather than being a direct cause of adverse outcomes. As such, the current study should help ease some concerns. The study offers some degree of reassurance that episodic hypoglycemia that occurs as a result of glucose-control efforts is likely not directly harmful to patients but the findings do not necessarily suggest that people should be implementing aggressive glucose control in AMI patients--that's a different question. This issue has been highlighted, in a different patient population, by the NICE-SUGAR results, which suggested that intensive glucose control (a target of 81 to 108 mg/dL), as compared with conventional control (180 mg/dL or less), does not offer any benefit and in fact may be harmful.