Diabetes is the medical term that describes a physical condition in which the body is unable to fully utilize insulin or doesn’t make enough insulin. But, there is another form of diabetes that doesn’t involve glucose. This is called Diabetes Insipidus. This particular form of diabetes isn’t as well publicized as Type 1 or Type 2 diabetes. Diabetes insipidus is a metabolic disorder, as is diabetes mellitus, but this is where the similarities end. (1)
One of the primary characteristics of Diabetes Insipidus is the large amount of urine that is excreted daily that is diluted. This means that the urine is mostly water and doesn’t contain enough waste products. People who suffer from diabetes insipidus have kidneys that have lost their ability to concentrate urine and return the water to the body to prevent dehydration.
Diabetes insipidus is also called DI. Those who suffer from DI also have a lack of anti-diuretic hormone that controls the concentration of the urine. The way in which individuals lose the ability to concentrate urine can happen in four different ways.
Four Types Of DI
Each of the four types of DI must be treated differently. The most common cause of DI is the result of a lack of vasopressin. This is a hormone that is produced by the back portion of the pituitary gland. This is often referred to as posterior DI, central DI or neurogenic DI. This portion of the pituitary gland can be destroyed by a variety of conditions that range from tumors, head injuries or brain infections. It is a diagnosis that physicians watch for after each of these other underlying medical conditions. (2,3)
The goal of treatment for each of the different types of DI is to first prevent dehydration. Then the physicians must look for the reason behind the destruction of the pituitary gland so those reasons can also be addressed prior to another problems arising. In the case of head injury, physicians are aware of the causative factors. However, without a head injury they must then investigate the possibility of pituitary tumor or subclinical brain infection.
Approximately 50% of the time the causative factors behind the diagnosis of DI isn’t found. When the reason can’t be identified it is called idiopathic. And, although DI is a permanent condition that affects the rest of an individual’s life, there are a variety of drugs, namely DDAVP, which can control the symptoms.
On occasion there is damage done to the pituitary gland during pregnancy that results in the symptoms of DI during the pregnancy but resolves approximately 4-6 weeks after the baby is born. Another reason that DI can occur during pregnancy is because the placenta metabolizes the hormone too quickly before the mother’s kidneys can use it to concentrate her urine.
The hormone vassopressin can also be suppressed by an excessive intake of fluid. This situation is called primary polydipsia. Polydipsia is the term used to describe a person who is drinking excessive amounts of fluid. This is more common in people who have an abnormality in the thirst trigger in their brain. Another type of polydipsia is caused from psychosomatic causes for which there is not a definitive treatment identified. (4)
Individuals who develop the symptoms of DI outside of the hospital may look similar to Diabetes mellitus, or sugar diabetes. They will have excessive urination and thirst. However, no sugar will be lost in the urine and the sufferer will not have excess sugar in the blood stream. In fact, glucose doesn’t play a part in the condition at all.
Urination continues throughout the day and night time. This can be very problematic for children because it can result in bed wetting. It also interferes with eating, growth, weight gain and appetite. Children may present to their pediatrician with fever, vomiting or diarrhea. Adults who aren’t diagnosed can stay healthy for years as long as they stay hydrated. However, this puts both adults and children at higher risk for dehydration which also can lead to other significant problems.
The amount of fluid that determines polydipsia, or excessive drinking, is based on the amount of fluid per kilograms of body weight. The standard is 50 ml/kg of body weight. This means that a person who weighs 150 pounds and drinks more than 1 gallon per day would have a higher than normal intake
At this point these are the only reasons that physicians and researchers have identified that idiopathic DI develops. Physicians do know that other health risks may be present based on the cause of the DI and the potential hazards of treating the underlying cause may create more problems.
People who suffer from Diabetes Insipidus have several lifestyle restrictions to ensure that they don’t become dehydrated. They must take their medication in order to live a normal life that will not include using the bathroom frequently or drinking large amounts of fluid. Those who suffer from DI should always wear a Medic Alert bracelet in order to alert emergency medical personnel of the special needs required for treatment in case you can’t communicate.
(1) National Kidney and Urologic Disease Information clearinghouse: Diabetes Insipidus
(2) Critical Care Nurse: Central Neurogenic Diabetes Insipidus Syndrome of Inappropriate Secretion of Antidiuretic Hormone and Cerebral Salt-wasting Syndrome in Traumatic Brain Injury
(3) Office of Rare Disease Research: Neurogenic Diabetes Insipidus
(4) Oxford Journals: Vasopressin Secretion in Primary polydipsia and Cranial Diabetes Insipidus