Diabetes insipidus occurs when the body’s fluids become unbalanced.
Normally, the body balances fluid volume and composition, with the fluid intake governed by thirst and the rate of excreting urine by the production of vasopressin, also called antidiuretic hormone (ADH).
This hormone is made in a small gland in the brain called the hypothalamus.
The ADH is then stored in the nearby pituitary gland and released when needed into the bloodstream.
When the ADH reaches the kidneys, it concentrates urine by reabsorbing some of the filtered water into the bloodstream, therefore making less urine.
When this system is not working properly, in other words, when the kidneys’ ability to regulate fluids does not work well, the result is often DI.
How does a doctor test for diabetes insipidus?
Because diabetes insipidus and diabetes mellitus have a crossover of symptoms, chiefly frequent urination and excessive thirst, a health care provider may suspect that a person with DI actually has diabetes mellitus. Therefore, testing is needed to distinguish the difference, including urinalysis (to determine the concentration of a person’s urine) and a fluid-deprivation test (which will change body weight, urine output, and urine concentration when fluids are withheld, all of which can be used to learn whether there is any defect in ADH production or the kidneys’ response to ADH).
What are the various forms of diabetes insipidus (DI)?
There are several different forms of diabetes insipidus. The following lists some of these forms and the factors that explain the differences:
Central DI , This is the most common form of DI. It is caused by damage to the pituitary gland, which stops the normal storage and release of ADH (antidiuretic hormone). Damages to the pituitary gland can be caused by a variety of diseases, head injuries, neurosurgery, or even genetic disorders.
Nephrogenic DI , This is caused by a disruption in the kidneys’ ability to respond to ADH. The disruption can be caused by various drugs (lithium, for example) or by several types of chronic diseases, such as sickle-cell disease, inherited genetic disorders, kidney failure, or partial blockage of the ureters. It is often treated with several drugs, including hydrochlorothiazide.
Dipsogenic DI , This is caused by an actual defect in or damage to the body’s thirst mechanism, which is located in the brain’s hypothalamus. Abnormal increase in thirst and fluid intake are seen in a person with this problem, and those, in turn, suppress ADH secretion, and increase the urine output. So far, there is no real treatment for dipsogenic DI. (For more about ureters and the urinary system, see the chapter “How Diabetes Affects the Urinary System.”)
Gestational DI , Similar to gestational diabetes, gestational DI occurs only during pregnancy, but that is where the similarity ends. Gestational DI results when a specific enzyme made by the placenta destroys the ADH in the mother. (The placenta is the system of tissues and blood vessels that develop with the fetus; it is attached to the mother, supplying nutrients and eliminating waste products between the fetus and mother.) It is most often treated with desmopressin (although there is a rare form of gestational DI, in which the thirst mechanism is abnormal, which is not treated with desmopressin).
What is “uric acid diabetes”?
According to a recent study, there may be a connection between uric acid and how the body metabolizes carbohydrates and fats (lipids).
The researchers suggested the phrase “uric acid diabetes” after discovering a statistically high incidence of diabetes in people with hyperuricemia (an abnormally high amount of uric acid in the blood), gout, or both.
But more studies need to be conducted to verify whether there truly is a uric acid, diabetes connection. (For more about uric acid, see the chapter “How Diabetes Affects the Urinary System.”)
The Handy Diabetes Answer Book
DIABETES AND BODY CONNECTIONS
SOME HUMAN MOLECULES AND DIABETES
What are the major organic molecules in humans?
The major organic (also called bioorganic) molecules in the human body are carbohydrates, lipids (or fats), proteins, and nucleic acids. These molecules are characteristic of all life, from the smallest to largest cells. They all have basic roles in the body’s cells, such as storing and producing energy, providing structural materials within a cell, and storing hereditary information. (For more information about carbohydrates, lipids, and fats, see the chapter “Diabetes and Food.”)
Are glucose levels affected by carbohydrates, fats, and proteins?
Yes, glucose levels in the body are affected by what a person eats, whether the foods contain carbohydrates, fats, or proteins (along with vitamins, minerals, and other nutrients). All of these bioorganic molecules can affect people’s glucose levels whether they have diabetes or not, albeit in different ways.
What is an enzyme?
An enzyme is a protein that acts as a biological catalyst.
It decreases the amount of energy needed (activation energy) to start a metabolic reaction.
Different enzymes work in different environments, owing to changes in temperature and acidity.
For example, the amylase enzyme that is active in the mouth cannot function in the acidic environment of the stomach; pepsin, which breaks down proteins in the stomach, cannot function in the mouth.
In fact, without enzymes, the stomach would not be able to obtain energy and nutrients from food.
In the human body, there are thousands (ranging from 1,000 to 5,000 depending on the source of information) of enzymes that help with cellular reactions.
What are proteins, and what is their purpose?
Proteins are large, complex molecules composed of smaller subunits called amino acids. Human life could not exist without proteins, as these complex molecules help build, maintain, and repair the body and especially the body’s cells.
What are some important enzymes, or proteins, in the human body?
The enzymes that are required for all metabolic reactions are proteins. These proteins also are important to structures such as muscles, and they act as both transporters and signal receptors. The following lists the types of proteins and examples of their functions, including those associated with blood glucose:
Type of Enzyme/Protein
Examples of Functions
Defensive
Antibodies that respond to invasion
Enzymatic
Increase the rate of reactions; build and break down molecules
Hormonal
Insulin and glucagon, which control blood glucose levels
Receptor
Cell-surface molecules that cause cells to respond to signals
Storage
Store amino acids for use in metabolic processes
Structural
Major components of muscles, skin, hair
Transport
Hemoglobin carries oxygen from lungs to cells
THE IMMUNE SYSTEM, INFECTION, AND INFLAMMATION
What is an autoimmune disease?
An autoimmune disease is one in which the body triggers an immune response against its own cells and tissues. Autoimmune diseases can affect almost every organ and system in the body. The cause or causes of most autoimmune diseases is unknown. They may be systematic (meaning they affect and damage many organs) or localized (affecting only a single organ or tissue). The following lists only a few autoimmune diseases that affect certain body systems (those associated with diabetes are italicized):
Autoimmune Diseases and Their Effects
Body System
Autoimmune Diseases
Blood and blood vessels
Autoimmune hemolytic anemia; pernicious anemia; systemic lupus; Wegener’s granulomatosis
Digestive tract
Autoimmune hepatitis; Crohn’s disease; scleroderma; ulcerative (including the mouth) colitis
Eyes
Sjögren’s syndrome; type 1 diabetes mellitus
Glands
Graves’ disease; thyroiditis; type 1 diabetes mellitus
Heart
Myocarditis; rheumatic fever; scleroderma; systemic lupus
Joints
Rheumatoid arthritis; systemic lupus erythematosus
Kidneys
Systemic lupus erythematosus; type 1 diabetes mellitus
Lungs
Rheumatoid arthritis; scleroderma; systemic lupus erythematosus
Muscles
Myasthenia gravis; polymyositis
Nerves and brain
Guillain-Barré syndrome; multiple sclerosis; systemic lupus erythematosus
Skin
Psoriasis; scleroderma; systemic lupus erythematosus
Besides diabetes, what other illnesses are often caused by the body’s own immune system’s “attacking” itself?
One explanation for the development of type 1 diabetes is thought to be the immune system’s antibodies attacking the insulin-producing cells in the pancreas.
But this is not the only way the body’s immune system “mutinies” against itself, attacking the organs it is supposed to defend.
For example, autoimmune diseases include rheumatoid arthritis, in which antibodies attack the tissues of the joints.
Another is multiple sclerosis, which is thought to be caused when antibodies attack the myelin sheath surrounding nerves. (For more about arthritis and diabetes, see the chapter “How Diabetes Affects Bones, Joints, Muscles, Teeth, and Skin.”)
What is the difference between inflammation and infection?
Inflammation does not mean infection, even when the infection causes the inflammation. An infection is caused by a bacteria, fungus, or virus, while an inflammation is the body’s response to the infection.
Scleroderma is an autoimmune disease affecting the skin, in many cases, but it can also afflict internal organs such as the lungs and kidneys.
Do people with diabetes often have more infections?
Yes. Because high blood glucose levels can weaken a person’s immune system, along with damaging nerves and reducing blood flow, people with diabetes are more apt to have infections. These include infections of the skin (in particular the feet), bladder, kidney, and mouth, and for women, often vaginal infections.
Do older people with diabetes seem to have more infections?
Yes, according to some studies, older people with diabetes seem to get more infections. In particular, common sites of such infections include the urinary tract, along with the skin (mostly areas that remain moist; for instance, the groin and armpits), and the soft structures (for example, between the toes) and bony structures (such as with bunions) of the feet. There are several reasons for more of these infections in the elderly, especially a less-efficient immune system, traumas, neuropathies, and infections that go unnoticed or are ignored by the person.
Which skin cells are involved with the immune system and deterring infections?
Keratinocytes, found in the top layer of skin called the epidermis, assist the immune system.
They produce hormone-like substances that stimulate the development of certain white blood cells called T lymphocytes.
In turn, the T lymphocytes defend against infection caused by disease-causing pathogens, mainly bacteria and viruses. (For more about the skin, see the chapter “How Diabetes Affects Bones, Joints, Muscles, Teeth, and Skin.”) For people with diabetes, defense against infections is often less efficient, as high blood glucose levels often weaken their immune system.
What are the types of immune responses in the body?
The body has two major forms of ridding the body of disease or invading microbes that result in inflammation.
Natural (or innate) immunity operates against microorganisms and dead cells and cell parts and is usually present when a person is born.
The body’s acquired immunity responds to the presence of specific antigens (toxins, often) and is usually acquired after birth as the body is exposed to certain antigens as the person ages.
For example, if a person gets a splinter, the tissue around the entry wound becomes irritated, hot, painful, red, and swollen.
This is the result of the body’s immune response to fight off the microorganisms that are on the splinter.
In this case, the body’s immune system sends out what are called phagocytes, or cells in the blood that (if working properly) approach their prey, engulf it, and destroy it with special enzymes.