Type 1 diabetes (IDDM)

Type 1 diabetes

Formerly called diabetes "lean" or diabetes "juvenile" diabetes type 1 or insulin-dependent diabetes mellitus (IDDM), the result of a rapid total failure of the pancreas to secrete insulin, a hormone needed to feed the cells of glucose, their first energy fuel.

The disease is caused by the destruction of insulin -producing endocrine cells , called β cells ( a particular cell type islets scattered in the pancreas ) . Hyperglycemia , which signs the diagnosis of diabetes, occurs when 80 % to 90 % of β cells have been destroyed . The corollary is that the illness that led to the destruction of cells begins years before the onset of hyperglycemia. This is actually an autoimmune disease characterized by abnormal activation of a family of key cells of the immune system , T cells , vis-à -vis substances or tissues normally present in the body, in this case the pancreatic β cells. Are also activated also other lymphocytes, B lymphocytes , which produce autoantibodies capable of binding to the β cells. The detection of autoantibodies is a good biological diagnostic test for type 1 diabetes in patients whose blood sugar is high .

An increase in incidence, causes partially unknown

Type 1 diabetes accounts for 5 % to 10 % of diabetes cases reported in the world , far behind type 2 diabetes ( non-insulin dependent ) . The WHO estimates that 180 million the total number of diabetics in the world ( 10 to 15 million for type 1 diabetes ), with 1.1 million deaths in 2005. According InVS , the incidence of type 1 diabetes in children and adolescents in France is 13.5 people per 100 000 (2004) , a steady increase in the last twenty years ( 3.7 % per year ) . Importantly, the disease often occurs in young subjects ( one in two by age 20 ) in which the only treatment currently available is to overcome the lack of insulin secretion by multi- daily injections of the hormone. Modern injection forms used today have greatly improved the treatment of the disease.

Type 1 diabetes occurs on a genetic predisposition . More than 20 genes have been found, probably a low estimate. The largest is located in the HLA ( a genetic region that control graft rejection , another consequence of the activation of T lymphocytes). Environmental factors, such as viruses , are probably involved in triggering the disease that led to the initial activation of T lymphocytes But none has so far been clearly identified. Some environmental factors, including infectious , also paradoxically a protective effect vis-à -vis diabetes.

Symptoms and evolution

The type 1 diabetes clinic, that is to say, the appearance of hyperglycemia can occur suddenly , within days or weeks. The symptoms are characteristic : Frequent and copious urination including at night (polyuria) , abnormal thirst ( polydipsia ) , rapid weight loss paradoxically associated with a larger appetite (hence the old name of diabetes "lean" ) , fatigue General intense, with or without nausea and vomiting , blurred vision .

The major complications of diabetes are retinopathy ( damage accumulation of small vessels of the retina , causing blindness to fifteen years in 2 % of cases, and significant visual impairment in 10% of patients) , neuropathy ( nerve damage with tingling , pain, numbness or weakness in the hands and feet , resulting with poor blood circulation to the risk of ulcers and amputation) , renal failure (10% and 20% of causes of death in diabetic ) , heart disease and the risk of stroke (50 % of deaths) . But these complications occur only ten or twenty years after the onset of hyperglycemia, and basically when hyperglycemia has been poorly controlled by insulin treatment .

Acute complications: major risks

In addition to these chronic and long-term developments, three concern the acute complications of type 1 diabetes: hyperglycemia (high elevations in blood sugar followed by a passage of glucose in the urine), hypoglycemia (with risk diabetic coma after falling blood sugar not mitigated) and ketoacidosis (transformation of fatty acids into ketones, which can also evolve into a diabetic coma).

Treatment and research

The main treatment of type 1 diabetes is insulin , which is to replace insulin in default by several daily injections of insulin synthesis , combined with strict dietary discipline and a measure of blood sugar several times a day on a drop of blood collected in order at the end of a finger. The administration of insulin can also be achieved by continuous infusion under the skin through small pumps attached to the belt, a treatment praised by some patients.

The basic, clinical and public health work in numerous tracks: better understanding of risk factors ( genetic , viral or environmental) and cellular mechanisms involved , definition of targets and new therapeutic means ( biotherapy ) , improved comfort life of patients and their families , social and psychological support . An optimal strategy would be to " immunize " the subject at the discovery of diabetes, or better before his appearance in order to inactivate specific lymphocyte β cells. The detection of autoantibodies in even normoglycemic is a predictive test before the onset of diabetes . But there is still presently no reliable and safe treatment that can block cell activation and prevent disease.

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