The issue of glycemic control in critically ill patients is as controversial as it is important. There is no doubt that high serum glucose (hyperglycemia) is detrimental for the injured body. The adverse effects of hyperglycemia are simply too numerous to list. At the same time, insulin was shown to have a beneficial effect on the immune system outside of its glucose lowering capacity.

Earlier clinical studies also showed a significant benefit of better glycemic control especially for the cardiovascular patients. Tight glycemic control had become the next big thing in Critical Care Medicine. Many hospitals across the nation rushed to develop glycemic control protocols for their ICU patients.

If tight glucose control is good for the surgical and cardiac patients, it must be good for the medical ICU patients as well, right? Oops… not really. A recent large international randomized study published in the New England Journal of Medicine showed that the patients in the intensive insulin therapy group, actually, had higher mortality. No benefits were shown regarding ICU length of stay and infection rates.

One possible explanation, of course, is that hypoglycemia (low blood sugar) is almost inevitable with intensive insulin treatment and that can offset any possible benefits of the tight glycemic control.

Well, what about subgroup analysis? Maybe we shouldn’t bundle all critically ill patients together, but to look at surgical, medical and trauma patients separately. The same study showed possible benefit for trauma patients treated more aggressively with insulin.

A study published in the April 2010 issue of the Journal of Trauma looked at possible benefits of intensive insulin therapy in patients with severe traumatic brain injury. It was a small study conducted in Brazil.

The study showed no benefit of intensive insulin therapy on neurological outcome, mortality, infection rate or length of ICU stay. Not surprisingly, patients randomized to more intensive therapy had a higher incidence of hypoglycemia. Low sugar is detrimental for the injured brain and that likely offset any possible benefits of intensive insulin therapy.

Is it possible to control blood glucose tightly without causing hypoglycemia? This way we can provide the patients with the benefit of normal blood glucose and avoid the downfall of low glucose. Theoretically, this is possible. In clinical practice, though, tight glycemic control without hypoglycemia remains an illusive target.

Everything that has been said above does not mean that we should not treat high blood glucose in critically ill patients. It’s just like everything else in medicine - common sense is what we ultimately need.