It is fascinating to observe how the approach to the diagnosis and treatment of a particular medical condition evolves over time. The treatment of hyperglycemia in the setting of critical illness represents one such example. It has been known for years that critically ill patients become hyperglycemic for a number of different reasons. Alterations in glucose metabolism including insulin resistance are common. There are numerous adaptive responses, such as increased catecholamine secretion, and elevations in serum cortisol and glucagon, that can also result in hyperglycemia. As a medical student some 20 years ago, hyperglycemia was viewed as more of an epiphenomenon. Though frequently observed in the ICU, most physicians did not think that it was directly pathogenic. This resulted in a laissez fair approach to treatment. In general, I was taught then to keep the blood glucose (BG) level at < 300 mg/dL with occasional doses of relatively small amounts of subcutaneous insulin.