The purpose of this study is to determine if there is any difference between two ways of controlling blood sugar with insulin. In patients admitted to the intensive care unit, blood sugar levels often rise due to the stress of illness or surgery. Studies have shown that patients do better if their blood sugar is kept normal. In order to maintain normal blood sugar levels, the investigators often give insulin (a substance made by the body), and they decide how much to give based on how high the blood sugar is. This study will compare two different ways of deciding how much insulin to give and compare how well each method keeps the blood sugar in a normal range. Both ways of controlling blood sugar are institutionally-approved protocols and part of routine care.