Risks associated with control of blood sugar in the ICU

Efforts by hospital intensive-care unit teams to reduce glucose readings of patients with diabetes might do more harm than good, according to an analysis published in Diabetes Care. Dr. Michael Schwartz, lead author and a UW Medicine endocrinologist, said he decided to study the phenomenon after talking with Dr. Irl Hirsch, a colleague who had witnessed problems emerge among his patients in the ICU.

Schwartz and co-authors found that, among patients with diabetes, efforts to reduce blood glucose levels to what is considered normal in a non-diabetic person may actually harm the patients by triggering a dangerous reaction.

The article noted that relative hypoglycemia - or a decrease in glucose greater than or equal to 30% below prehospital admission levels - “has emerged as a major clinical concern because the standard glycemic target recommended for patients in the intensive care unit is associated with an increased mortality risk among some of the critically ill patients with diabetes.”

Patients with diabetes generally have a higher blood sugar level (100 to 200 mg/dL) than patients without diabetes, the study noted. For a patient without diabetes, normal levels are 70 to100 mg/dL

“The target range that is established in in the ICUs doesn’t differentiate between a patient with diabetes and a patient without diabetes,” Schwartz said. To establish the best blood sugar range, he said, a randomized clinical trial would need to determine the ideal glycemic level for ICU patients with, and without, diabetes.

People with diabetes usually have higher than normal blood sugar levels. Over time their bodies get used to these high blood sugar levels. As a consequence, when their blood sugars levels are brought into the normal range with treatment, their bodies incorrectly perceive the levels to be dangerously low, thereby triggering the counter regulatory response. 

Schwartz and his colleagues are studying how the body monitors and regulates blood sugar levels to try to understand how this response might be prevented or corrected.