Diabetes insipidus and diabetes mellitus are very different conditions. The commonality between the two, besides the word "diabetes," is that both involve thirst and urination. Beyond this point the conditions differ significantly. The National Diabetes Information Clearinghouse defines three main types of diabetes mellitus and various other forms, all acting upon insulin levels that regulate blood sugar. Diabetes insipidus has four types and none of the forms relate to insulin production or regulation. Furthermore, the causes of the conditions, the hormones affected and condition management all differ between diabetes insipidus and mellitus.
Cause and Commonality
Diabetes insipidus is uncommon compared to diabetes mellitus in the general population. The cause of diabetes insipidus stems from an antidiuretic hormone, which is produced in the hypothalamus and stored in the pituitary gland at the base of the brain. MayoClinic.com indicates that the process of fluid excretion signaled by the hormone to the kidneys is disrupted either due to a defect in the kidney tubules or because of damage to the brain impacting the release of the antidiuretic hormone. The cause of diabetes mellitus is an insufficiency in a different hormone that is produced in the pancreas--either in the production of the hormone, or in the body's ability to respond to it. Diabetes mellitus is also referred to as sugar diabetes because the disease centers around the body's inability to properly process glucose, a form of sugar that is the body's primary energy source.
Vasopressin is a hormone created and secreted by the brain for controlling water metabolism. According to the National Kidney and Urologic Diseases Information Clearinghouse, when this hormone is secreted to the kidneys it directs the kidneys to concentrate urine through a filtration process. In the presence of diabetes insipidus, this process of communication from the production and secretion of vasopressin is disrupted before reaching the kidneys.
Diabetes mellitus acts on the hormone insulin, made in the pancreas. Insulin controls carbohydrate metabolism to manage sugar levels in the body. In the event of diabetes mellitus, the bodys production of insulin or its use of the hormone is insufficient, leading to a buildup of sugar in the blood stream.
Symptoms and Management
Diabetes insipidus and mellitus commonly share the symptoms of sudden or excessive urination and excessive thirst. Diabetes insipidus can cause dehydration if fluid balance is not maintained. In diabetes mellitus, excessive appetite, fatigue and weight changes may also occur. The Diabetes Insipidus Foundation indicates that management of this condition involves balancing fluid intake with output, using a synthetic medication hormone to replace vasopressin or use of a specific diuretic. Treatments to manage diabetes mellitus involve correcting insulin levels either through medications or changing nutrition habits.