In a healthy individual, the hormone insulin facilitates the transport of sugars through the cell membrane - much like a key that opens the cell membrane to let the sugar in. This is the process that breaks down in diabetes. It is considered the more serious, life-threatening form of the disease. Type II, or adult onset, diabetics produce insulin but, for reasons as yet unexplained, the body doesn't recognize the insulin. In other words, they have the key, but it no longer fits the lock.
Sugars continue to come into the body but they have no place to go.
Then, excessive levels of sugar and excessive levels of insulin are present in the blood of these patients. It's a double whammy - too much sugar and too much insulin. If this situation is allowed to continue, the cells that produce the insulin eventually burn out. When this happens, the Type II diabetic becomes a Type I diabetic. To manage the levels of sugar and insulin in the blood, Type II diabetics often take medication to reduce sugar absorption or improve insulin efficiency.