Article: Diabetes mellitus type 1

Diabetes mellitus type 1 is a form of diabetes mellitus.

Type 1 diabetes (formerly known as "childhood" or "juvenile" diabetes or "insulin dependent" diabetes) is most commonly diagnosed in children and adolescents. The adult incidence of Type 1 is the same as for children [1], leading to the name change from juvenile diabetes. Many adults diagnosed with Type 1 are misdiagnosed as Type 2 diabetics, leading to the misconception of Type 1 as a disease of children.

The most important forms of diabetes are due to decreases in or the complete absence of the production of insulin (type 1 diabetes), or decreased sensitivity of body tissues to insulin (type 2 diabetes). The most valid laboratory test to distinguish Type 1 from Type 2 diabetes is the C-peptide test, which detects the amount of insulin being produced in the body. Lack of insulin resistance, determined by a glucose tolerance test, would also be suggestive of Type 1.

Pathophysiology

Type I diabetes is an autoimmune disorder, in which the body's own immune system attacks the beta cells in the Islets of Langerhans of the pancreas, destroying them or damaging them sufficiently to reduce or eliminate insulin production. The autoimmune attack may be triggered by reaction to an infection, for example by one of the viruses of the Coxsackie virus family.

Some researchers believe that the autoimmune response is influenced by antibodies against cow's milk proteins. A large restrospective case controlled study published in 2006 found that infants who were never breast fed had twice the risk for developing Type 1 diabetes as infants who were breast fed for at least 3 months. The mechanism, if any, is not understood. [2] Research has not been able to establish a connection between autoantibodies, antibodies to cow's milk proteins, and Type 1 diabetes. [3] [4] [5]

A subtype of type 1 (identifiable by the presence of antibodies against beta cells) develops slowly and so is often confused with Type 2. In addition, a small proportion of type 1 cases have the hereditary condition maturity onset diabetes of the young (MODY) which can also be confused with Type 1.

Vitamin D in doses of 2000 IU per day given during the first year of child's life has been connected in one study in Northern Finland (where the intrinsic production of Vitamin D is low) with a reduction in the risk of getting type I diabetes later in life (by 80%) [6]. Vitamin D3 may be an important pathogenic factor in type 1 diabetes independent of geographical latitude [7].

Some chemicals and drugs specifically target the pancreas. Vacor (N-3-pyridylmethyl-N'-p-nitrophenyl urea), a rodenticide introduced in the United States in 1975, selectively destroys panacreatic beta cells, resulting in Type 1 diabetes after accidental or intentional ingestion. [8] Vacor was withdrawn from the U.S. market in 1979. Zanosar is the trade name for streptozotocin, an antibiotic and antineoplastic agent used in chemotherapy for pancreatic cancer, that kills beta cells, resulting in loss of insulin production. [9]

Other pancreatic problems including trauma, pancreatitis or tumors (either malignant or benign) can also lead to loss of insulin production.

Treatment

Currently, type 1 is treated with insulin injections, inhalable insulin, lifestyle adjustments, and careful monitoring of blood glucose levels using blood test kits. Insulin delivery is also available by an insulin pump, which allows the infusion of insulin 24 hours a day at preset levels, and the ability to program push doses (bolus) of insulin as needed at meal times. The treatment must be continued indefinitely. Experimental replacement of beta cells (by transplant) is being investigated in several research programs and may become clinically available in the future. For more on managing the disease, see Diabetes Management.

Prevalence

About 5-10% of all North American diabetics have Type 1. The fraction of type 1 cases in other parts of the world differs; this is likely due to both differences in the rate of type 1 and differences in the rate of other types, most prominently type 2. Most of this difference is not currently understood. Variable criteria for categorizing diabetes types may play a part.

Curing Type 1 Diabetes

Although type 1 diabetes is not currently curable, there are several approaches being researched:

• Pancreas transplantation
  • Pancreas transplants are not generally recommended because introducing a new, functioning pancreas to a patient with diabetes can have negative effects on the patient's normally functioning kidney. For patients with kidney failure, however, a pancreas transplant is a viable option.
• Islet cell transplantation
  • Less invasive than a pancreas transplant, Islet cell transplantation is considered a very promising approach to curing type 1 diabetes. In this procedure, Islet cells are injected into the patient's liver, where the cells take residence and begin to produce insulin. The liver is chosen because it is more accessible than the pancreas and the Islet cells seem to produce insulin well in that environment. The patient's body, however, will treat the new cells just as it would any other introduction of foreign tissue: the immune system will attack the cells as it would a viral infection. Thus, the patient also needs to undergo treatment involving immunosuppressants, which reduce immune system activity. Recent studies have shown that Islet cell transplants have progressed to the point that 58% of the patients in one study were insulin independent one year after the operation.^[10]
• Artificial pancreas development
• Genetic engineering (fat or muscle cells that don't normally make insulin have a human insulin gene inserted — then these "pseudo" islet cells are transplanted into people with type 1 diabetes)
• Immune modification
  • Shutting down the autoreactive T cells that attack beta islet cells, allowing the islet cells to regenerate. Denise Faustman is investigating this hypothesis at Mass General Hospital, in Boston.
• Stem cells
  • Research is being done at several locations in which islet cells are grown from stem cells. As of now they have been transplanted into mice and rats with some success.

Further reading

• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) - Diabetes in America Textbook (PDFs)

Notes

1. ↑  Mayo Clinic: "Islet cell transplant: Emerging treatment for type 1 diabetes," 2005.

Links

• Children with Diabetes
• Type 1 Diabetes at the American Diabetes Association
• The Juvenile Diabetes Forum sponsored by the Juvenile Diabetes Research Foundation