Diabetes is a disease process in which the body can't move glucose, or sugar, from the bloodstream into the cells. The full name of the disease, diabetes mellitus, reflects the fact that the condition results in the production of sugar-containing urine--"mellitus" comes from the Latin word for sweet--a sign that sugar is remaining in the blood instead of moving into the cells.
Significance
Following consumption of carbohydrate-containing food--food that includes either sugar or starch--the human digestive tract breaks large sugar and starch molecules into their smaller components. Glucose is one such component, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." The intestines then absorb glucose and other components of carbohydrates into the bloodstream. Ideally, from there, the glucose is taken up by cells, but not in diabetics.
Function
The purpose of cellular uptake of glucose is to provide a source of nutrition and energy to cells, which metabolize glucose by chemically burning it--combining it with oxygen--a process that releases energy that the cells can use and produces the waste products carbon dioxide and water. If the cells can't take up glucose from the bloodstream, explains Dr. Lauralee Sherwood in her book "Human Physiology," they aren't able to chemically burn glucose and begin to starve.
Types
Diabetes comes in two forms, notes Sherwood. Type 1 diabetes, sometimes called juvenile onset diabetes, is a disease that becomes apparent in childhood and is the result of an inability of the pancreas to produce the hormone insulin, which is a "gatekeeper" hormone that causes cells to take up glucose. In type 2 diabetes, the pancreas can produce insulin, but cellular receptors don't respond to the hormone, so cells don't take up glucose.
Prevention/Solution
Diabetics have to moderate their diet and lifestyle in several important ways. Type 1 diabetics are insulin-dependent, explains Dr. Gary Thibodeau in his book "Anatomy and Physiology." Upon consumption of carbohydrates, they must inject themselves with the hormone insulin to allow cells to take up the nutritional molecules. Type 2 diabetics can't rely on insulin, but instead must control blood sugar by eating meals low in glucose, and meals that are absorbed slowly. Type 2 diabetics who are overweight benefit from weight reduction, which often alleviates symptoms.
Expert Insight
Not all sugars are insulin-dependent, note Garrett and Grisham. Fructose, for instance, is another type of sugar and is closely related to glucose. Like glucose, fructose is a constituent of table sugar, or sucrose, and is one of the two components of table sugar that is released when the intestines digest sucrose. Unlike glucose, fructose doesn't require insulin for cellular uptake. As such, diabetics can often use small amounts of fructose in the diet without raising blood sugar significantly.
References
- "Biochemistry"; Reginald Garrett and Charles Grisham; 2007
- "Human Physiology"; Lauralee Sherwood; 2004
- "Anatomy and Physiology"; Gary Thibodeau; 2007
