Dextrose is a common name for the ubiquitous sugar molecule, glucose. In nature, dextrose is exceedingly common. Starch, as in rice and potatoes, is made up of long chains of dextrose, while table sugar contains dextrose chemically bonded to fructose, another sugar molecule. A very important nutritional molecule, the cells rely upon a constant level of dextrose in the bloodstream. Overconsumption of the sugar, however, can lead to a variety of side effects.
Perhaps the most severe side effects of dextrose are reserved for individuals with underlying disease processes. Type 1 and type 2 diabetics have an inability to either produce or respond to insulin, a pancreatic hormone that is released in response to high levels of blood sugar. If a diabetic eats foods containing large amounts of dextrose, their blood sugar levels will rise very high very quickly, explains Dr. Lauralee Sherwood in her book "Human Physiology." This leads to a number of symptoms, all of which are linked to hyperglycemia, or high blood sugar. Diabetic hyperglycemia is very serious and, if untreated, can lead to tissue damage, coma and death.
Even in those without diabetes, overuse of dextrose can result in some very undesirable side effects. While the body cells need dextrose to survive--the brain, in particular, is very dextrose dependent and uses it preferentially over any other form of fuel. The body also has mechanisms for storing extra fuel. These storage mechanisms, notes Dr. Gary Thibodeau in his book "Anatomy and Physiology," are primarily in the form of fat storage. While fat storage helped humans survive periods of starvation during historical times when food was scarce, most modern Americans rarely need to rely on fat stores to survive. As such, one side effect of excess dextrose consumption--an increase in body fat--is very undesirable to most.
Interestingly enough, too much dextrose can actually lead to a paradoxical effect in individuals without diabetes. If blood sugar rises very high very quickly, the pancreas secretes very large quantities of insulin. This signals the cells to take up blood sugar quickly, since hyperglycemia is damaging to the tissues. As a result of the pancreatic overreaction to very high blood sugar, however, the cells can take up too much blood sugar, leading to low blood sugar levels, or hypoglycemia. This, notes Dr. Sherwood, leads to feelings of nausea, hunger and dizziness--side effects that are quite uncomfortable.