Carbohydrates or sugars are an important energy source to meet the caloric
needs of the patient. In meeting the energy needs of humans, the "large"
calorie unit or kilocalories, abbreviated as kcals, is used. As a caloric
source, there are between 3.4 to 4 kcal per gram of carbohydrate. In
adults, the normal caloric requirement is between 25 to 30 kcals per kg of
body weight each day. As in the above example of a 70 kg patient, the
amount of calories from carbohydrate sources could be in the range of 1750
to 2100 kcals or per day, but often much less, as fat is also an important
caloric source. If therapy is provided by a catheter into the stomach or
intestine, whole or complex sources of carbohydrates are used, such as from
corn syrup, whereas if therapy is provided by an intravenous catheter, the
carbohydrate source is in a simplified form as glucose or dextrose sugars.
During acute illness however, many patients will not tolerate even modest
amounts of carbohydrates and may develop high blood sugar or glucose
levels. High blood glucose levels are associated with an increased risk of
infections. To minimize this complication, not only can the amounts of
carbohydrate reduced even further, but blood sugar control with aggressive
insulin therapy is given. In addition, a portion of the carbohydrate
calories may be substituted with fat to further reduce the need the chances
of high blood sugars.