What causes diabetes

Source: medical treatment network

Cause diabetes mellitus has been the world of the important issues covered. After decades of research, agreed that diabetes is a syndrome of complex etiology. Although the etiology of diabetes has not yet been fully clarified, but the investigation of clinical epidemiology, genetics, immunology, virology, pathology, endocrine and metabolic disease areas such as the comprehensive study of known and closely related to the following factors.

(1) genetic factors: As early as more than 60 years ago, the international medical community found in the relatives of diabetics, the incidence of diabetes was significantly higher than the general population. Is a kind of genetic characteristics of genes through the cell to the offspring chromosome. Monozygotic twins have the same chromosome, the egg-on-one genetic disease similar to the observation is of great significance. Pyke of the United Kingdom for up to one-egg twin more than 20 years of follow-up. In 1982 he summed up the 200 pairs of monozygotic twin survey of diabetes. Twin in the 200 cases of insulin-dependent diabetes mellitus of the 147 pairs of non-insulin-dependent diabetes mellitus of 53 right. Twin has diabetes are referred to as the line Up to the time of statistics for only one twin is called inconsistent diabetes. Insulin-dependent diabetes mellitus in which the same rate of twin 54.4%, non-insulin-dependent diabetes mellitus twin rate of 90.6 percent agreed. Twin eggs from a single analysis of the survey can be seen in non-insulin-dependent diabetes mellitus than the genetic tendency to insulin-dependent diabetes mellitus is more significant.

What diabetes gene, the way in which the genetic is not very clear, but the view is more or less the same number of genes on the basis that: ① diabetes incidence and clinical manifestations of the ethnic differences are obvious; ② different clinical diabetes types, such as insulin-dependent diabetes mellitus, non-insulin-dependent diabetes. Known incidence of adolescent non-insulin-dependent diabetes mellitus (MODY) is a autosomal dominant genetic disease; ③ species have been found more than 40 genetic diseases associated with impaired glucose tolerance or diabetes, diabetes is a part of these genetic diseases. For example, Wolfran syndrome, there is optic atrophy, deafness, diabetes insipidus and diabetes. More than 40 kinds of genetic diseases, respectively, as a result of different mutation loci, but may affect glucose metabolism, resulting in high blood sugar, indicating that multiple genes and glucose metabolism; ④ animal model of diabetes also showed genetic heterogeneity, such as Japan NoD is a rat insulin-dependent diabetes mellitus, New Zealand and the NIO rat Wellesle y mice non-insulin-dependent diabetes mellitus. In short, according to the available scientific information, the majority of scholars believe that diabetes mellitus is due to genetic mutation, a number of individuals have a genetic mutation so that diabetes susceptibility, that is to say not through the genes of diabetes itself, but the susceptibility to diabetes, On this basis as well as environmental factors (virus infection, obesity, etc.) the role of diabetes can occur.

(2) human leukocyte antigen system (HLA) study: human leukocyte antigen system (HLA), also known as major histocompatibility antigen (MHC). Human HLA antigen system to control gene in the short arm of chromosome VI. HLA antigen system includes three main categories: the first category is the antigen HLA-A,-B,-C antigens, widely distributed in the surface of eukaryotic cells, involved in cell-mediated immunity, mainly related to organ transplant rejection-related. The second category is based on D antigen antigen family, that is, HLA-DP,-DQ,-DR antigen mainly distributed in the B lymphocytes, macrophages, endothelial cells and activated T lymphocytes, mainly related to autoimmune diseases pathogenesis-related. The third type of antigen is C2, Bf, C4A and C4B, such as the complement system.

Separation of blood lymphocytes, using immunological methods can be carried out on the B lymphocyte antigen HLA analysis of the second category. Study shows that: insulin-dependent diabetes mellitus with HLA closely related, HLA-DR3,-DR4 antigen frequency was significantly higher, HLA-DR2 antigen frequency decreased significantly. Analysis from the family, brothers and sisters of the HLA haplotypes, if the two haplotypes are the same as with the patient, the opportunities for diabetes is 1 / 5; if there is only one haplotype with the patient the same, the occurrence of diabetes the opportunity is 1 / 20; if two haplotypes are different with the patient, the opportunities for diabetes is 1 / 100. HLA-specific changes in insulin-dependent diabetes that is autoimmune diseases. Non-insulin-dependent diabetes mellitus patients with the HLA typing of the same general population, non-specific.

(3) environmental factors: The genetic basis of susceptibility to diabetes with the people, environmental factors and the occurrence of diabetes plays an important role in development. Environmental factors include the following:

① virus infection: As early as 1864, doctors found a case of mumps Norwegian patients, diabetes soon. The virus infection after the report of an endless stream of diabetes. Diabetes-related virus, mumps virus, rubella virus, Coxsackie virus, cytomegalovirus and encephalitis, myocarditis virus. Virus infection resulted in destruction of islet cells may have the following three: A virus through the individual susceptibility of diabetic islet cell membrane of the virus to enter the B cell receptor, and some B cell acute necrosis, followed by cell lysis. London in 1988 St. Mary's Hospital emergency admission of a young Chinese men (22 years), abdominal discomfort and vomiting for 36 hours in history, past physical health,glucose 92mmol / L, plasma insulin <2μU / L, blood pH7.1 . Diagnosed with insulin-dependent diabetes mellitus, ketoacidosis, 1 hour after admission died. 34 hours after death for autopsy found that B cells of all islet necrosis, and pancreatic islet A, D cells are normal in a large number of islet cells, eosinophilic cells, macrophages and polymorphonuclear leukocyte infiltration. Death can not check for virus serology, in accordance with its histological lesions showed that the virus caused a rapid and comprehensive islet B cell necrosis, the short course is very rare. B virus-susceptible individuals through the cell membrane of islet B virus to enter the B cell receptor, the long-term stay, so that slow down cell growth, cell life span shortened, B cells gradually reduced, and to stimulate their own immune system, a number of years after diabetes. Such as rubella virus invasion in the fetal period, after several years or after more than ten years of clinical diabetes. The United States to observe 24 1 cases of congenital rubella syndrome patients, 30 cases found 17 cases of diabetes and impaired glucose tolerance; Australia reported 45 cases of congenital rubella syndrome, which occurred in 9 cases of diabetes. C virus by the B cell membrane receptors into the B cells in HIV, the virus nucleic acid into host B cell gene, so that B cells in the insulin gene mutates abnormal insulin synthesis. Despite the occurrence of HIV infection among young people the importance of environmental factors in IDDM, but still has a genetic basis for susceptibility to HIV infection and immune response caused by factors such as their own before the incidence.

② obesity: obese non-insulin-dependent diabetes mellitus and development occurred in an important environmental factors. Obesity means weighing 20 percent more than standard body weight; or by calculating body mass index: body mass index (BMI) = weight (kg) / height 2 (m2), male BMI ≥ 2 5, female BMI ≥ 27, for the obese. According to the United States over the age of 30 reported the incidence of diabetes by about 80% ~ 90% body weight over ideal body weight 1 5%, in 1981 the report of Professor Zhong Xueli 300,000 population in our country the results of the census of diabetes, body weight over ideal body weight more than 10% of the population, men suffering from diabetes disease rate of 23.20 ‰, female 18.05 ‰, while the prevalence of normal weight to 4.08 ‰, 3.66 ‰. Obese insulin-target cells as a result of the decrease in the number of insulin receptor or insulin receptor binding and cellular responses after the defects generated in vivo insulin resistance and high blood sugar. Obesity the same duration, while the more prone to high blood sugar. The causes of obesity-related genetic and familial. The majority as a result of long-term excessive intake of high calorie, high-sugar high-fat diet, reduced physical activity, increase in body fat storage.

③ Chemical Toxicology: B cells as a direct material damage to four alloxan and streptozotocin in the United States and South Korea as a rodent topiramate drug use, such as metronidazole benzene urea. Toxicology of these chemicals due to diabetes than may in IDDM, and in the etiology of human IDDM seems to very little meaning, only to explain the pathogenesis of cell damage as an important part, and most patients are not the cause of these poisons.

④ eating certain food components: incidence of IDDM in Iceland more than boys for those born in October, so the general suspicion in the mother before and after pregnancy is the Christmas may be related to a large number of food containing nitroso compounds related to the preservation of meat. Animal experiments have confirmed that consumption of animal Aberdeen smoked meat can be caused by diabetes.

⑤ malnutrition: the reported number in Africa or Southeast Asia in cassava-eating countries and areas of diabetes, is different from the clinical manifestations of IDDM, is also different from NIDDM, may be related to consumption of cassava-related. Because a large number of cassava intake and low protein intake, especially lack of sulfur amino acids, can cause cyanide accumulation in the body and damage the pancreas. Other animal experiments and clinical long-term protein nutritional deficiencies can lead to reduced insulin secretion impaired glucose tolerance.

Another long-term effects of excessive tension and glucose metabolism of drugs such as diuretics, glucocorticoid, steroid, such as oral contraceptives may increase insulin requirements, increase the islet B cell load, the environment is one of the factors of diabetes.