When most people think of diabetes they are thinking about a disease called diabetes mellitus. This disease causes fluctuations in blood glucose levels. Type I diabetes mellitus is when the pancreatic beta cells do not produce enough insulin to lower the blood glucose concentration. Type II diabetes mellitus or "adult onset" is called a lifestyle disease which is brought on by our poor diets and lack of exercise. In type II DM, the pancreatic beta cells produce enough insulin but the body builds up insulin resistance.
Another type of diabetes is called diabetes insipitous. This type of diabetes has absolutely nothing to do with blood glucose but rather is a hyposecretion of a hormone called ADH, antidiuretic hormone. ADH is secreted by the brain and it regulates intravascular fluid volumes in the body. A person with DI voids an unusually high volume of urine which can lead to a host of problems like dehydration and electrolyte disturbances.