Insulin-dependent diabetics can find themselves low on blood sugar if they overdose on insulin or go too long without eating. This is very dangerous to the brain, and quickly leads to coma. Such individuals commonly use glucose drinks to significant benefit and with essentially no side effects. Most individuals who are free from disease have very little reason to use glucose drinks routinely. Glucose drinks may have significant side effects if used by a non-diabetic, however.
One of the first effects of a glucose drink not medically indicated is a simple sugar overdose. While this isn't dangerous, it is associated with some potentially uncomfortable symptoms similar to those an individual would feel if she drank too much soda or ate too much candy. Sugar highs can cause a feelings of excitation, particularly in children. Note Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry," glucose is absorbed very quickly into the bloodstream from the digestive tract, so sugar highs typically begin within ten minutes after consumption of large quantities of sugar.
Oddly, exceedingly low blood sugar is the second effect of sugar overdose resulting from non-diabetic glucose use. The reason for this paradoxical response is that the body attempts to maintain blood sugar within strict parameters. If levels rise too high in a very short period of time, as they do in the case of sugar overdose, the pancreas secretes large quantities of the hormone insulin, explains Dr. Lauralee Sherwood in her book, "Human Physiology." The large amounts of insulin cause rapid uptake of glucose by cells, which depletes blood sugar and leads to hunger, shakiness, and feelings of weakness.
The human body is designed to store excess energy for later use. Two primary storage mechanisms include storing glucose as the carbohydrate glycogen in the liver and converting glucose to fat for storage in fat cells, explain Drs. Mary Campbell and Shawn Farrell in their book, "Biochemistry." Very high levels of insulin release that occur following a sugar overdose lead to significant conversion of glucose to fat. For this to occur, glucose is partially metabolized to the smaller molecule acetyl-CoA, which is then converted to longer chain fatty acid molecules and eventually triglycerides, or storage fat.