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March 26, 2016
Table of Contents

1 Introduction
Diabetes mellitus type 1

Wikipedia

 

Diabetes mellitus type 1 (Type 1 diabetes, IDDM, or juvenile diabetes) is a form of diabetes mellitus that results from autoimmune destruction of insulin-producing beta cells of the pancreas. The subsequent lack of insulin leads to increased blood and urine glucose. The classical symptoms of polyuria (frequent urination), polydipsia (increased thirst), polyphagia (increased hunger), and weight loss result.

Type 1 diabetes is fatal unless treated with insulin. Injection is the most common method of administering insulin; insulin pumps and inhaled insulin have been available at various times. Pancreas and islet transplants have been used to treat type 1 diabetes; however, islet transplants are currently still at the experimental trial stage.

Most people who develop type 1 are otherwise healthy. Although the cause of type 1 diabetes is still not fully understood it is believed to be of immunological origin. There is a growing body of evidence that diet may play a role in the development of type 1 diabetes, through influencing gut flora, intestinal permeability, and immune function in the gut; wheat in particular has been shown to have a connection to the development of type 1 diabetes, although the relationship is poorly understood. Type 1 can be distinguished from type 2 diabetes via a C-peptide assay, which measures endogenous insulin production.

Type 1 treatment must be continued indefinitely in all cases. Treatment need not significantly impair normal activities, if sufficient patient training, awareness, appropriate care, discipline in testing and dosing of insulin is taken. However, treatment is burdensome for many people. Complications may be associated with both low blood sugar and high blood sugar. Low blood sugar may lead to seizures or episodes of unconsciousness and requires emergency treatment. High blood sugar may lead to increased tiredness and can also result in long term damage to organs.



The classical symptoms of type 1 diabetes include: polyuria (frequent urination), polydipsia (increased thirst), polyphagia (increased hunger), tiredness, and weight loss.


Environment

Environmental factors can strongly influence expression of type 1. A study showed that for identical twins, when one twin had type 1 diabetes, the other twin only had type 1 30%–50% of the time. Despite having exactly the same genome, one twin had the disease, where the other did not; this suggests that environmental factors, in addition to genetic factors, can influence disease prevalence.

Genetics

Type 1 diabetes is a polygenic disease, meaning many different genes contribute to its expression. Depending on locus or combination of loci, it can be dominant, recessive, or somewhere in between. The strongest gene, IDDM1, is located in the MHC Class II region on chromosome 6, at staining region 6p21. This is believed to be responsible for the histocompatibility disorder characteristic of type 1: Insulin-producing pancreas cells (beta cells) display improper antigens to T cells.




The cause of type 1 diabetes is not fully understood. One theory, discussed by DeLisa Fairweather & Noel R. Rose, among others, proposes that type 1 diabetes is a virally triggered autoimmune response in which the immune system attacks virus infected cells along with the beta cells in the pancreas. The Coxsackie virus family or German measles is implicated, although the evidence is inconclusive. In type 1, pancreatic beta cells in the Islets of Langerhans are destroyed decreasing endogenous insulin production. This distinguishes type 1's origin from type 2 DM. The type of diabetes a patient has is determined only by the cause—fundamentally by whether the patient is insulin resistant (type 2) or insulin deficient without insulin resistance (type 1).

This vulnerability is not shared by everyone, for not everyone infected by the suspected organisms develops type 1 diabetes. This has suggested presence of a genetic vulnerability and there is indeed an observed inherited tendency to develop type 1. It has been traced to particular HLA genotypes, though the connection between them and the triggering of an auto-immune reaction is still poorly understood.

Short breast-feeding period and short attendance to day care is associated with the risk of type 1 diabetes in Czech children.

Some researchers believe that the autoimmune response is influenced by antibodies against cow's milk proteins. No connection has been established between autoantibodies, antibodies to cow's milk proteins, and type 1 diabetes. A subtype of type 1 (identifiable by the presence of antibodies against beta cells) typically develops slowly and so is often confused with type 2. In addition, a small proportion of type 2 cases manifest a genetic form of the disease called maturity onset diabetes of the young (MODY).

Vitamin D in doses of 2000 IU per day given during the first year of a child's life has been connected in one study in Northern Finland (where intrinsic production of Vitamin D is low due to low natural light levels) with an 80% reduction in the risk of getting type 1 diabetes later in life. The causal connection, if any, is obscure.

Type 1 diabetes was previously known as juvenile diabetes because it is one of the most frequent chronic diseases in children; however, the majority of new-onset type 1 diabetes is seen in adults. Scientific studies that use antibody testing (glutamic acid decarboxylase antibodies (GADA), islet cell antibodies (ICA), and insulinoma-associated autoantibodies (IA-2)) to distinguish between type 1 and type 2 diabetes demonstrate that most new-onset type 1 diabetes is seen in adults. A 2008 book, Type 1 Diabetes in Adults: Principles and Practice, says that adult-onset type 1 autoimmune diabetes is two to three times more common than classic childhood-onset autoimmune diabetes. In type 1 diabetes, the body does not produce insulin. Insulin is a hormone that is needed to maintain normal blood glucose levels (3.6 to 5.8 mM glucose) within the body, when spikes in blood glucose concentration occurs. One mechanism by which insulin does such is by causing the liver to take up glucose molecules and convert them to glycogen for storage in the liver.

Some chemicals and drugs preferentially destroy pancreatic cells. Pyrinuron (Vacor, N-3-pyridylmethyl-N'-p-nitrophenyl urea), a rodenticide introduced in the United States in 1976, selectively destroys pancreatic beta cells, resulting in type 1 diabetes after accidental or intentional ingestion. Vacor was withdrawn from the U.S. market in 1979, but is still used in some countries. Zanosar is the trade name for streptozotocin, an antibiotic and antineoplastic agent used in chemotherapy for pancreatic cancer; it also kills beta cells, resulting in loss of insulin production. Other pancreatic problems, including trauma, pancreatitis or tumors (either malignant or benign), can also lead to loss of insulin production.

The exact cause(s) of type 1 diabetes are not yet fully understood, and research on those mentioned, and others, continues.



This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Diabetes mellitus type 1".


Last Modified:   2010-11-08


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