Dwarfism (pronounced dwo[?]fiz’m IPA: /’dw???f?z?m/) is a medical term describing a person of short stature, with the most widely accepted definition of a dwarf being a person with an adult height of less than 4 feet 10 inches (147cm). [1] Dwarfism can be caused by over 200 separate medical conditions, and as such the symptoms of individual dwarfs can vary greatly. People who are affected by dwarfism are often referred to as “little people.”[2]

Characteristics of dwarfism vary greatly in individuals. Disproportionate dwarfism is identified by one or more body parts being disproportionately large or small compared to the rest of the body, with growth abnormalities in specific areas being apparent. In cases of proportionate dwarfism the body parts are proportional to each other with a general lack of growth being apparent. Hypotonia is common in dwarfs, but intelligence and life span are usually normal.

The most common cause of dwarfism is achondroplasia, a bone growth disorder responsible for 70% of dwarfism cases.[1] In cases of achondroplasia the limbs are disproportionally short compared to the trunk, with the head being larger than normal and frontal bossing being apparent on the face. Conditions in humans characterized by disproportional body parts are typically caused by one or more genetic disorders in bone or cartilage development. Forms of extreme shortness in humans characterized by proportional body parts usually have a hormonal or nutritional cause such as growth hormone deficiency, once known as “pituitary dwarfism”.[2]

There is no universal treatment for dwarfism. Individual abnormalities such as bone growth disorders can sometimes be treated through surgery, and some hormone disorders can be treated through medication, but in most cases it is impossible to treat all of the symptoms of dwarfism. Most of the time lifestyle remedies are needed in order to cope with the effects of dwarfism. In-home devices like specialized furniture is often needed to help people who have dwarfism function normally. Many support groups also exist in order to help sufferers of dwarfism cope with the challenges they face and to help them function independently.

Dwarfism is a highly visible condition that can often carry negative connotations in society. Some believe that people afflicted with dwarfism are intellectually challenged or have personality disorders. Due to their unusual height, people with dwarfism are often used as spectacles in entertainment or portrayed with derogatory stereotypes. In popular culture dwarfs are often portrayed in roles directly related to their abnormal height. Heightism is a serious problem that can lead to ridicule as a child and discrimination as an an adult for a person with dwarfism.

Dwarfism is a medical disorder with the sole requirement being an adult height of under 4 foot 10 inches. The term “dwarfism” can be ambiguous, but the underlying syndromes have their own specific classifications. Dwarfism is not usually referred to as a medical disfunction in its own right, but is used to describe a category of syndromes that all have the end effect of short stature. Individuals with dwarfism are medically termed as either dwarfs or little people.

The universal defining characteristic of dwarfism is an adult height of less than 4 feet 10 inches. Since those afflicted with dwarfism have such a wide range of physical characteristics, oddities in individuals are understood by diagnosing and observing the underlying disorders.

Disproportionate dwarfism is characterized by one or more body parts being disproportionately large or small compared to the rest of the body. In achondroplasia the trunk is normally sized with the limbs being disproportionately short, the head being larger than usual, and the forehead being prominent.[3] Facial features are often affected and individual body parts may have problems associated with them. Orthopedic problems can arise across multiple conditions such as diastrophic dysplasia and pseudoachondroplasia.

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Dupuytren’s contracture (also known as “Morbus Dupuytren,” “Dupuytren’s disease,” or “Palmar fibromatosis”[1], and sometimes misspelled as Dupuytren’s constricture) is a fixed flexion contracture of the hand where the fingers bend towards the palm and cannot be fully extended (straightened). It is named after Baron Guillaume Dupuytren, the surgeon who described an operation to correct the affliction.

The ring finger and little finger are the fingers most commonly affected. The middle finger may be affected in advanced cases, but the index finger and the thumb are nearly always spared. Dupuytren’s contracture progresses slowly and is usually painless. In patients with this condition, the tissues under the skin on the palm of the hand thicken and shorten so that the tendons connected to the fingers cannot move freely. The palmar aponeurosis becomes hyperplastic and undergoes contracture.

Incidence increases after the of 40; at this age men are affected more often than women. After the age of 80 the distribution is about even.

In Dupuytren’s disease, the tough connective tissue within one’s hand becomes abnormally thick which can cause the fingers to curl and can result in impaired function of the fingers, especially the small and ring fingers. It usually has a gradual onset, often beginning as a tender lump in the palm. Over time, pain associated with the condition tends to go away, but tough bands of tissue may develop. [1] These bands, which are the source of the reduced mobility commonly associated with the condition, are visible on the surface of the palm and may appear similar to a small callus. It commonly develops in both hands and has no connection to dominant or non-dominant hands, nor any correlation with right- or left-handedness.

The contracture sets in slowly, especially in women. However, when present in both hands and when there is associated foot involvement, it tends to progress more rapidly.

Dupuytren’s disease is a very specific affliction, and primarily affects:

Some suspected, but unproven causes of Dupuytren’s contracture include trauma, diabetes, alcoholism, epilepsy and liver disease. There is no proven evidence that hand injuries or specific occupational exposures lead to a higher risk of developing Dupuytren’s disease although there is some speculation that Dupuytren’s may be caused or at least the onset may be triggered by physical trauma, such as manual labor or other over-exertion of the hands. However, the fact that Dupuytren’s is not connected with handedness casts some doubt on this claim.[2]

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Duchenne muscular dystrophy (DMD) is a severe recessive X-linked form of muscular dystrophy characterized by rapid progression of muscle degeneration, eventually leading to loss in ambulation and death. This affliction affects one in 3500 males, making it the most prevalent of muscular dystrophies. In general, only males are afflicted, though females can be carriers. The disorder is caused by a mutation in the gene DMD, located in humans on the X chromosome. The DMD gene codes for the protein dystrophin, an important structural component within muscle tissue. Dystrophin provides structural stability to the dystroglycan complex (DGC), located on the cell membrane.

Symptoms usually appear in male children before age 6 and may be visible in early infancy. Progressive proximal muscle weakness of the legs and pelvis associated with a loss of muscle mass is observed first. Eventually this weakness spreads to the arms, neck, and other areas. Early signs may include pseudohypertrophy (enlargement of calf muscles), low endurance, and difficulties in standing unaided or inability to ascend staircases. As the condition progresses, muscle tissue experiences wasting and is eventually replaced by fat and fibrotic tissue (fibrosis). By age 10, braces may be required to aide in walking but most patients are wheelchair dependent by age 12. Later symptoms may include abnormal bone development that lead to skeletal deformities, including curvature of the spine. Due to progressive deterioration of muscle, loss of movement occurs eventually leading to paralysis. Intellectual impairment may or may not be present but if present, does not progressively worsen as the child ages. The average life expectancy for patients afflicted with DMD varies from early teens to age mid 30s. There have been reports of DMD patients surviving past the age of 40 and even 50.

Duchenne muscular dystrophy is caused by mutations in the DMD gene, which is located on the X chromosome. Due to this, DMD has an incidence of 1 in 3,500[1] newborn males. Mutations within the DMD gene can either be inherited or occur spontaneously during germline transmission.

DMD is named after the French neurologist Guillaume Benjamin Amand Duchenne (1806-1875), who first described the disease in 1861. [2]

Duchenne muscular dystrophy is caused by a mutation of the dystrophin gene at locus Xp21. Dystrophin is responsible for the connection of muscle fibers to the extracellular matrix through a protein complex containing many subunits. The absence of dystrophin permits excess calcium to penetrate the sarcolemma (cell membrane). In a complex cascading process that involves several pathways and is not clearly understood, increased oxidative stress within the cell damages the sarcolemma, and eventually results in the death of the cell. Muscle fibers undergo necrosis and are ultimately replaced with adipose and connective tissue.

The main symptom of Duchenne muscular dystrophy is progressive neuromuscular disorder that is muscle weakness associated with muscle wasting with the voluntary muscles[citation needed] being first affected, especially the pelvis and calf muscles. Muscle weakness also occurs in the arms, neck, and other areas, but not as early as in the lower half of the body. Symptoms usually appear before age 6 and may appear as early as infancy. Generalized weakness and muscle wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are often enlarged. The other physical symptoms are:

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Down syndrome, Down’s syndrome, or trisomy 21 is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British doctor who described the syndrome in 1866. The disorder was identified as a chromosome 21 trisomy by Jérôme Lejeune in 1959. The condition is characterized by a combination of major and minor differences in structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Down syndrome in a baby can be identified with amniocentesis during pregnancy or at birth.

Individuals with Down syndrome tend to have a lower than average cognitive ability, often ranging from mild to moderate developmental disabilities. A small number have severe to profound mental disability. The incidence of Down syndrome is estimated at 1 per 800 to 1,000 births, although these statistics are heavily influenced by the age of the mother. Other factors may also play a role.

Many of the common physical features of Down syndrome also appear in people with a standard set of chromosomes. They may include a single transverse palmar crease (a single instead of a double crease across one or both palms, also called the Simian crease), an almond shape to the eyes caused by an epicanthic fold of the eyelid, upslanting palpebral fissures (the separation between the upper and lower eyelids), shorter limbs, poor muscle tone, a larger than normal space between the big and second toes, and protruding tongue. Health concerns for individuals with Down syndrome include a higher risk for congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions.

Early childhood intervention, screening for common problems, medical treatment where indicated, a conducive family environment, and vocational training can improve the overall development of children with Down syndrome. Although some of the physical genetic limitations of Down syndrome cannot be overcome, education and proper care will improve quality of life.[1]

Individuals with Down syndrome may have some or all of the following physical characteristics: oblique eye fissures with epicanthic skin folds on the inner corner of the eyes, muscle hypotonia (poor muscle tone), a flat nasal bridge, a single palmar fold, a protruding tongue (due to small oral cavity, and an enlarged tongue near the tonsils), a short neck, white spots on the iris known as Brushfield spots,[2] excessive joint laxity including atlanto-axial instability, congenital heart defects, excessive space between large toe and second toe, a single flexion furrow of the fifth finger, and a higher number of ulnar loop dermatoglyphs. Most individuals with Down syndrome have mental retardation in the mild (IQ 50–70) to moderate (IQ 35–50) range,[3] with individuals having Mosaic Down syndrome typically 10–30 points higher.[4] In addition, individuals with Down syndrome can have serious abnormalities affecting any body system. They also may have a broad head and a very round face.

Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (trisomy 21) or part (such as due to translocations). The effects of the extra copy vary greatly among people, depending on the extent of the extra copy, genetic history, and pure chance. Down syndrome occurs in all human populations, and analogous effects have been found in other species such as chimpanzees[5] and mice. Recently, researchers have created transgenic mice with most of human chromosome 21 (in addition to the normal mouse chromosomes).[6] The extra chromosomal material can come about in several distinct ways. A typical human karyotype is designated as 46,XX or 46,XY, indicating 46 chromosomes with an XX arrangement typical of females and 46 chromosomes with an XY arrangement typical of males.[7]

Trisomy 21 (47,XX,+21) is caused by a meiotic nondisjunction event. With nondisjunction, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 21; the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21. Trisomy 21 is the cause of approximately 95% of observed Down syndromes, with 88% coming from nondisjunction in the maternal gamete and 8% coming from nondisjunction in the paternal gamete.[8]

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Donohue syndrome (also known as Leprechaunism) is an extremely rare and severe genetic disorder. Leprechaunism derives its name from the fact that those afflicted with the disease often have elfin features and are smaller than usual. Affected individuals have an insulin receptor with greatly impaired functionality.

Facial features indicative of Donohue syndrome include protuberant and low-set ears, flaring nostrils, and thick lips. Physical features include stunted growth (including during gestation), an enlarged clitoris and breasts in affected females, and an enlarged penis in affected males. In the Journal of Pediatric Medicine, Donohue and Uchida described affected sisters whose growth appeared to have ended in the seventh month of gestation, both born alive but dying before four months of age.[1] Very early death (or spontaneous abortion) is the norm, although sufferers sometimes live longer than a decade.[1][2]

As the mutation causing the disorder affects insulin receptor function, those with the disease are also insulin resistant, with hypoglycemia and profound hyperinsulinemia (very high levels of insulin in the blood)[1] Another feature of the disease is that the subcutaneous Adipose tissue is markedly diminished. (Contributing to the unusual appearance of affected individuals.)

A much milder form of the disease, in which there is some insulin resistance but normal growth and subcutaneous fat distribution, is also known.[3] It is caused by a less severe mutation of the same gene.

Donohue syndrome is an autosomal recessive genetic disorder. The mutations responsible for the disorder are found on the short arm chromosome 19 (19p13.2) within the coding sequence of the INSR gene (insulin receptor) causing the production of inactive receptor molecules.[2] There are several mutations that can be responsible for the disease, as any mutation that severely impairs the functionality of the insulin receptor will have similar effects. The INSR gene spans over one hundred and twenty thousand base pairs, which contain twenty-two exons coding for a protein that consists of 1382 amino acids. [4]. Some of the introns may or may not be spliced out depending on the kind of cell. [5]

Known mutations to the gene which can cause Donahue syndrome include a nonsense mutation that resulted in a frame shift[6], a single missense mutation[1] and in the milder form mentioned above, a single codon change that altered isoleucine to methionine in the receptor protein.[1] Some mutations to the gene instead result in insulin resistant diabetes without Donahue syndrom.[1]

As the mutations are extremely rare, most cases are the result of consanguineous matings, for instance between cousins.[1]. However, the exact mutation need not be the same: a sufferer may have two different mutant alleles.[7]

A heterozygous individual (i.e. one who is a carrier for the disease, having only one normal allele for the insulin receptor) will not be affected. Two heterozygous parents have, in theory, a one in four chance of having a child with the disease, and two thirds of their unaffected children will be carriers. However, because spontaneous abortion (miscarriage) often results when the fetus has the disease, in actuality the proportion of children born alive with Donahue syndrome will be lower than 25%.[1]

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Diverticulosis, otherwise known as “diverticular disease”, is the condition of having diverticula in the colon which are outpocketings of the colonic mucosa and submucosa through weaknesses of muscle layers in the colon wall. These are more common in the sigmoid colon, which is a common place for increased pressure. This is uncommon before the age of 40 and increases in incidence after that age.[1]

Diverticula are thought to be caused by increased pressure within the lumen of the colon. Increased intra-colonic pressure secondary to constipation may lead to weaknesses in the colon walls giving way to diverticula. Other causes may include a colonic spasm which increases pressure, which may be due to dehydration or low-fiber diets;[2] although this may also be due to constipation. Fiber causes stools to retain more water and become easier to pass (either soluble or insoluble fiber will do this). A diet without sufficient fiber makes the stools small, requiring the bowel to squeeze harder to remove the smaller stool.

Risk factors:

About 10% of the US population over the age of 40 and half over the age of 60 has diverticulosis. This disease is common in the US, Britain, Australia, Canada, and is uncommon in Asia and Africa. It is the most common cause for rectal bleeding in US adults over the age of 40 years.

Studies have identified dietary factors as potential explanations for the large variation in the disease. High intake of fiber, fruits and vegetables and brown bread was associated with approximately 40-50% reductions in the risk.[3] [4][5] On the other hand, higher intake of both red and processed meat increased the risk 2-4 fold in two studies,[4][3] while a third study found a 24-fold increase in the risk with higher total meat intake.[5] This could explain the lower risk among vegetarians.[6]

Dr. Denis Burkitt(1911-1993), who was the main proponent of the fiber theory, also believed that the use of the unnatural sitting posture for defecation is a major contributing factor in diverticulosis and other GI disorders (including hiatus hernias.)[7]

Contrary to a common recommendation to avoid eating popcorn, nuts and corn to prevent diverticular complications, a large prospective study of men indicates that the consumption of these foods does not increase the risk of diverticulosis or diverticular complications.[8][9]

Large mouth diverticula are associated with scleroderma.

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Diphtheria (Greek d?f?e?a (diphthera)—“pair of leather scrolls”) is an upper respiratory tract illness characterized by sore throat, low fever, and an adherent membrane (a pseudomembrane) on the tonsils, pharynx, and/or nasal cavity.[1] A milder form of diphtheria can be restricted to the skin. It is caused by Corynebacterium diphtheriae, an aerobic Gram-positive bacterium.[2]

Diphtheria causes the progressive deterioration of myelin sheaths in the central and peripheral nervous system leading to degenerating motor control and loss of sensation. Diphtheria is a contagious disease spread by direct physical contact or breathing the aerosolized secretions of infected individuals. Once quite common, diphtheria has largely been eradicated in developed nations through widespread vaccination. In the United States for instance, there were 52 reported cases of diphtheria between 1980 and 2000; between 2000 and 2007 there were only five cases[3] as the DPT (Diphtheria–Pertussis–Tetanus) vaccine is given to all school children. Boosters of the vaccine are recommended for adults since the benefits of the vaccine decrease with age without constant re-exposure; they are particularly recommended for those traveling to areas where the disease has not been eradicated.

In the 1920s there were an estimated 100,000 to 200,000 cases of diphtheria per year in the United States, causing 13,000 to 15,000 deaths per year.[3] Children represented a large majority of these cases and fatalities. One of the most famous outbreaks of diphtheria was in Nome, Alaska; the 1925 serum run to Nome to deliver diphtheria antitoxin is now celebrated by the “Great Race of Mercy”.

One of the first effective treatments for diphtheria was discovered in the 1880s by U.S. physician Joseph O’Dwyer (1841–1898). O’Dwyer developed tubes that were inserted into the throat, and prevented victims from suffocating due to the membrane sheath that grows over and obstructs airways. In the 1890s, the German physician Emil von Behring developed an antitoxin that did not kill the bacterium, but neutralized the toxic poisons that the bacterium releases into the body. Von Behring discovered that animal blood has antitoxins in it and so he took the blood, removed the clotting agents and injected it into human patients. Von Behring was awarded the first Nobel Prize in Medicine for his role in the discovery, and development of a serum therapy for diphtheria. (Americans William H. Park and Anna Wessels Williams; and Pasteur Institute scientists Emile Roux and Auguste Chaillou also independently developed diphtheria antitoxin in the 1890s.) The first successful vaccine for diphtheria was developed in 1913 by Behring. However, antibiotics against diphtheria were not available until the discovery and development of sulfa drugs.

The Schick test, invented between 1910 and 1911, is a test used to determine whether or not a person is susceptible to diphtheria. It was named after its inventor, Béla Schick (1877–1967), a Hungarian-born American pediatrician. A massive five-year campaign was coordinated by Dr. Schick. As a part of the campaign, 85 million pieces of literature were distributed by Metropolitan Life Insurance Company with an appeal to parents to “Save your child from diphtheria.” A vaccine was developed in the next decade, and deaths began declining in earnest in 1924.[4]

Diphtheria toxin catalyzes the ADP-ribosylation of, and inactivates, the elongation factor eEF-2.[5] In this way, it acts to inhibit translation during eukaryotic protein synthesis. The toxin enters the host cell and is hydrolysed by a trypsin-like protease to give a fragment with enzymatic activity. The toxin then transfers an ADP-ribose from NAD+ to a diphthamide residue, a modified histidine (amino acid), which is found within the EF-2 protein. EF-2 is needed for translocation of tRNA from the A-site to the P-site of the ribosome during translation. The ADP-ribosylation is reversible by administering high concentrations of nicotinamide, one of the reaction products.

The respiratory form has an incubation period of 2–5 days. The onset of disease is usually gradual. Symptoms include fatigue, fever, a mild sore throat and problems swallowing. Children infected have symptoms that include nausea, vomiting, chills, and a high fever, although some do not show symptoms until the infection has progressed further. In 10% of cases, patients experience neck swelling, informally referred to as “bull neck.” These cases are associated with a higher risk of death.

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Diabetic nephropathy (nephropatia diabetica), also known as Kimmelstiel-Wilson syndrome and intercapillary glomerulonephritis, is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. It is characterized by nephrotic syndrome and nodular glomerulosclerosis. It is due to longstanding diabetes mellitus, and is a prime cause for dialysis in many Western countries.

The syndrome was discovered by British physician Clifford Wilson (1906-1997) and German-born American physician Paul Kimmelstiel (1900-1970) and was published for the first time in 1936.

The syndrome can be seen in patients with chronic diabetes (15 years or more after onset), so patients are usually of older age (between 50 and 70 years old). The disease is progressive and may cause death two or three years after the initial lesions, and is more frequent in men. Diabetic nephropathy is the most common cause of chronic kidney failure and end-stage kidney disease in the United States. People with both type 1 and type 2 diabetes are at risk. The risk is higher if blood-glucose levels are poorly controlled. Further, once nephropathy develops, the greatest rate of progression is seen in patients with poor control of their blood pressure. Also people with high cholesterol level in their blood have much more risk than others.

The earliest detectable change in the course of diabetic nephropathy is a thickening in the glomerulus. At this stage, the kidney may start allowing more serum albumin (plasma protein) than normal in the urine (albuminuria), and this can be detected by sensitive medical tests for albumin. This stage is called “microalbuminuria”. It can appear 5 to 10 years before other symptoms develop. As diabetic nephropathy progresses, increasing numbers of glomeruli are destroyed by nodular glomerulosclerosis. Now the amounts of albumin being excreted in the urine increases, and may be detected by ordinary urinalysis techniques. At this stage, a kidney biopsy clearly shows diabetic nephropathy.

Kidney failure provoked by glomerulosclerosis leads to fluid filtration deficits and other disorders of kidney function. There is an increase in blood pressure (hypertension) and of fluid retention in the body (oedema). Other complications may be arteriosclerosis of the renal artery and proteinuria (nephrotic syndrome).

Throughout its early course, diabetic nephropathy has no symptoms. They develop in late stages and may be a result of excretion of high amounts of protein in the urine or due to renal failure:

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Diabetes mellitus (IPA: /?da??’bi?ti?z/ or /?da??’bi?t?s/, /m?’la?t?s/ or /’m?l?t?s/), often referred to simply as diabetes (Ancient Greek: d?aßa??e?? “to pass through”), is a syndrome of disordered metabolism, usually due to a combination of hereditary and environmental causes, resulting in abnormally high blood sugar levels (hyperglycemia).[2] Blood glucose levels are controlled by a complex interaction of multiple chemicals and hormones in the body, including the hormone insulin made in the beta cells of the pancreas. Diabetes mellitus refers to the group of diseases that lead to high blood glucose levels due to defects in either insulin secretion or insulin action.[3]

Diabetes develops due to a diminished production of insulin (in type 1) or resistance to its effects (in type 2 and gestational).[4] Both lead to hyperglycaemia, which largely causes the acute signs of diabetes: excessive urine production, resulting compensatory thirst and increased fluid intake, blurred vision, unexplained weight loss, lethargy, and changes in energy metabolism. Monogenic forms, e.g. MODY, constitute 1-5 % of all cases.[5]

All forms of diabetes have been treatable since insulin became medically available in 1921, but there is no cure. The injections by a syringe, insulin pump, or insulin pen deliver insulin, which is a basic treatment of type 1 diabetes. Type 2 is managed with a combination of dietary treatment, exercise, medications and insulin supplementation.

Diabetes and its treatments can cause many complications. Acute complications (hypoglycemia, ketoacidosis, or nonketotic hyperosmolar coma) may occur if the disease is not adequately controlled. Serious long-term complications include cardiovascular disease (doubled risk), chronic renal failure, retinal damage (which can lead to blindness), nerve damage (of several kinds), and microvascular damage, which may cause erectile dysfunction and poor wound healing. Poor healing of wounds, particularly of the feet, can lead to gangrene, and possibly to amputation. Adequate treatment of diabetes, as well as increased emphasis on blood pressure control and lifestyle factors (such as not smoking and maintaining a healthy body weight), may improve the risk profile of most of the chronic complications. In the developed world, diabetes is the most significant cause of adult blindness in the non-elderly and the leading cause of non-traumatic amputation in adults, and diabetic nephropathy is the main illness requiring renal dialysis in the United States.[6]

The term diabetes, without qualification, usually refers to diabetes mellitus, which is associated with excessive sweet urine (known as “glycosuria”) but there are several rarer conditions also named diabetes. The most common of these is diabetes insipidus in which the urine is not sweet (insipidus meaning “without taste” in Latin); it can be caused by either kidney (nephrogenic DI) or pituitary gland (central DI) damage

The term “type 1 diabetes” has universally replaced several former terms, including childhood-onset diabetes, juvenile diabetes, and insulin-dependent diabetes (IDDM). Likewise, the term “type 2 diabetes” has replaced several former terms, including adult-onset diabetes, obesity-related diabetes, and non-insulin-dependent diabetes (NIDDM). Beyond these two types, there is no agreed-upon standard nomenclature. Various sources have defined “type 3 diabetes” as, among others, gestational diabetes,[7] insulin-resistant type 1 diabetes (or “double diabetes”), type 2 diabetes which has progressed to require injected insulin, and latent autoimmune diabetes of adults (or LADA or “type 1.5″ diabetes.[8]) There is also maturity onset diabetes of the young (MODY) which is a group of several single gene (monogenic) disorders with strong family histories that present as type 2 diabetes before 30 years of age.

Type 1 diabetes mellitus is characterized by loss of the insulin-producing beta cells of the islets of Langerhans in the pancreas, leading to a deficiency of insulin. This type of diabetes can be further classified as immune-mediated or idiopathic. The majority of type 1 diabetes is of the immune-mediated variety, where beta cell loss is a T-cell mediated autoimmune attack.[3] There is no known preventive measure which can be taken against type 1 diabetes; it is about 10% of diabetes mellitus cases in North America and Europe (though this varies by geographical location), and is a higher percentage in some other areas. Most affected people are otherwise healthy and of a healthy weight when onset occurs. Sensitivity and responsiveness to insulin are usually normal, especially in the early stages. Type 1 diabetes can affect children or adults but was traditionally termed “juvenile diabetes” because it represents a majority of the diabetes cases in children.

The principal treatment of type 1 diabetes, even in its earliest stages, is the delivery of artificial insulin via injection combined with careful monitoring of blood glucose levels using blood testing monitors. Without insulin, diabetic ketoacidosis often develops which may result in coma or death. Treatment emphasis is now also placed on lifestyle adjustments (diet and exercise) though these cannot reverse the progress of the disease. Apart from the common subcutaneous injections, it is also possible to deliver insulin by a pump, which allows continuous infusion of insulin 24 hours a day at preset levels, and the ability to program doses (a bolus) of insulin as needed at meal times. An inhaled form of insulin was approved by the FDA in January 2006, although it was discontinued for business reasons in October 2007. [9][10] Non-insulin treatments, such as monoclonal antibodies and stem-cell based therapies, are effective in animal models but have not yet completed clinical trials in humans.[11]

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Diabetes insipidus (DI) (Greek d?aßa??e?? diabainein – to pass through and Latin insipidus – without taste) is a condition characterized by excretion of large amounts of severely diluted urine, which cannot be reduced when fluid intake is reduced. It denotes inability of the kidney to concentrate urine. DI is caused by a deficiency of antidiuretic hormone (ADH), also known as vasopressin, due to the destruction of the back or “posterior” part of the pituitary gland where vasopressin is normally released from, or by an insensitivity of the kidneys to that hormone. It can also be induced iatrogenically by various drugs.

Excessive urination and extreme thirst (especially for cold water and sometimes ice or ice water) are typical for DI. Symptoms of diabetes insipidus are quite similar to those of untreated diabetes mellitus, with the distinction that the urine is not sweet as it does not contain glucose and there is no hyperglycemia (elevated blood glucose). Blurred vision is a rarity. Signs of dehydration may also appear in some individuals since the body cannot conserve much (if any) of the water it takes in.

The extreme urination continues throughout the day and the night. In children, DI can interfere with appetite, eating, weight gain, and growth as well. They may present with fever, vomiting, or diarrhea. Adults with untreated DI may remain healthy for decades as long as enough water is drunk to offset the urinary losses. However, there is a continuous risk of dehydration.

In order to distinguish DI from other causes of excess urination, blood glucose levels, bicarbonate levels, and calcium levels need to be tested. Measurement of blood electrolytes can reveal a high sodium level (hypernatremia as dehydration develops). Urinalysis demonstrates a dilute urine with a low specific gravity. Urine osmolarity and electrolyte levels are typically low.

A fluid deprivation test helps determine whether DI is caused by:

This test measures changes in body weight, urine output, and urine composition when fluids are withheld and as dehydration occurs. The body’s normal response to dehydration is to concentrate urine and conserve water, so urine becomes more concentrated and urination becomes less frequent. Those with DI continue to urinate large amounts of dilute urine in spite of not drinking any fluids. Sometimes measuring blood levels of ADH during this test is also necessary.

To distinguish between the main forms, desmopressin stimulation is also used; desmopressin can be taken by injection, a nasal spray, or a tablet. While taking desmopressin, a patient should drink fluids or water only when thirsty and not at other times, as this can lead to sudden fluid accumulation in central nervous system. If desmopressin reduces urine output and increases osmolarity, the pituitary production of ADH is deficient, and the kidney responds normally. If the DI is due to renal pathology, desmopressin does not change either urine output or osmolarity.

If central DI is suspected, testing of other hormones of the pituitary, as well as magnetic resonance imaging (MRI), is necessary to discover if a disease process (such as a prolactinoma, or histiocytosis, syphilis, tuberculosis or other tumor or granuloma) is affecting pituitary function. Thankfully most people with this form either have experienced past head trauma or simply have stopped ADH production for no apparent reason.

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