To determine the effects of a diabetes specific enteral formula compared to a standard formula supplemented with protein (isocaloric and isonitrogenous) on the mean blood glucose and glycemic variability in a homogenous group of critically ill patients in a neurological ICU. Blood glucose will be recorded every minute using a continuous blood glucose monitor. The primary end points will be the difference between the mean blood glucose levels and the glucose variability between the control and intervention groups for the time period that the patient is in the ICU and receiving tube feeds and for up to a maximum of 14 days.