Glucose is a simple sugar that forms the basic building block of most of the carbohydrates in the human diet. The body attempts to maintain a constant level of glucose in the blood, and diabetes is a disease in which blood glucose consistently exceeds this level. Diabetes treatment consists of methods to keep blood glucose under control. Diet and insulin can both be useful facets of this treatment, but the relative importance of each varies greatly with the type of diabetes.
Glucose
All carbohydrates consist of combinations of the simple sugars, glucose, fructose and lactose. Sucrose or table sugar, for example, consists of one molecule of glucose joined with one molecule of fructose, while starches consist of thousands of linked glucose molecules. Glucose is the most important of the simple sugars because every organ in the body can use it for fuel. Because it is so important, the body tries to maintain a more or less constant level of glucose, neither too low nor too high.
Type 1 Diabetes
All carbohydrates are broken down into one of the three simple sugars by the digestive tract, and these sugars are then adsorbed into the blood. Since most carbohydrate in the human diet is built of glucose, a typical meal results in a considerable amount of glucose entering the blood. The pancreas responds to this glucose by secreting the hormone insulin, which causes cells in the body to take glucose out of the blood and use it for fuel. In type 1 diabetes, the insulin secreting cells of the pancreas are destroyed by autoimmune attack. Without insulin, glucose cannot leave the blood, resulting in diabetes.
Type 2 Diabetes
In the early stages of type 2 diabetes, the pancreas secretes plenty of insulin, but the cells in the body become less responsive to insulin's signal to take glucose out of the blood, a condition known as insulin resistance. Initially, the pancreas can simply secrete more insulin to overcome this resistance. High levels of insulin cause further insulin resistance, however, and insulin resistance eventually increases to the point where the pancreas can no longer keep up, resulting in diabetes.
Type 1 and Diet
Because most type 1 diabetics have minimal insulin-secreting capacity remaining by the time they are diagnosed, all type 1 diabetics need to use insulin. Diet can play a minor role in managing type 1 diabetes, as patients can control the carbohydrate content of each meal. The major challenge in insulin therapy is using enough insulin to deal with the glucose that is entering the blood after a meal without using too much and causing low blood sugar, which is also extremely dangerous. Therefore, the most important dietary consideration in type 1 diabetes is consuming a consistent amount of carbohydrate at each meal so that the insulin dose can be adjusted to the right level.
Type 2 and Diet
In contrast to type 1 diabetics, most type 2 diabetics do not need to start insulin therapy at the time of diagnosis, although they may need to begin using it later on, as the disease progresses. Because of the difficulties involved in insulin therapy, one of the major goals in the treatment of type 2 diabetes is to delay progression of the disease for as long as possible by decreasing insulin resistance, or at least slowing its increase. Diet plays a critical role in this process because weight loss is the most effective method currently known for reducing insulin resistance. The best evidence for this efficacy comes from weight loss surgery patients, who usually lose significant amounts of weight. For example, a study from the September 1995 edition of the "Annals of Surgery" found that 82.9 percent of 146 weight loss surgery patients with type 2 diabetes had normal blood sugar without medication seven years after their surgeries.
References
- "Lippincotts's Illustrated Reveiws: Biochemistry, 2nd. Ed."; Pamela C. Champe and Richard A. Harvey; 1994
- "Harrison's Principles of Internal Medicine 16th ed."; Dennis L. Kasper, et al. (eds.); 2005
- "Annals of Surgery"; "Who Would Have Thought It? An Operation Proves to Be the Most Effective Therapy for Adult-Onset Diabetes Mellitus"; WJ Pories, et. al.; Sep. 1995
