Type I Diabetes
Type I Diabetes Mellitus (T1DM) is an autoimmune disease, characterized by the destruction of β-cells from the Islets of Langerhans in the pancreas. The destruction leads to decreased or no production of insulin leading to elevated levels of glucose in the blood known as hyperglycemia. This leads to instant symptoms such as weight loss, polyuria and polydipsia. Other chronic symptoms may occur in the long run such as vascular diseases and degenerative diseases such as neuropathy and nephropathy. Although T1DM is one of the most common existing autoimmune diseases, affecting 20 million people globally, it only accounts for 5-10% of all diabetic cases. T1DM was not considered as an autoimmune disease until the discovery of pancreatic inflammation of islets as an indicator in 1965. Treatments for this disease have been under research for years, with advances being made along with improvements in the understanding of the disease. This essay will outline the genetic and environmental factors that cause this disease and its epidemiology, along with a description of its pathogenesis, experimental models, involvement in the immune system, current or possible treatments and methods of prevention. T1DM was thought to be presented in a sudden manner in children and during early adulthood, however, recent data shows that only 50-60% of T1DM cases present themselves those younger than 16-18 years, with a low incidence in adulthood. This is due to a highly variable period that is asymptomatic, where glucose metabolism is normal or very slightly disturbed, and it can range from a few months in infants to more than 10 years. Although the department of health has stated that the most frequent age of diagnosis is 10-14 years, the disease, according to data collected from Sweden, has recently shifted towards a younger age of manifestation. The data showed that the overall incidence of diabetes didn’t change, but the age at which incidence was most common had dropped. This suggests an increase in aggressive β-cell destruction, which could be associated with increased exposure to environmental factors or it could be correlated with the increasing weight of the population.  These factors could also be a contributor to the rising incidence of T1DM worldwide, which is approximately 2-5% per year. The incidence of T1DM varies in different geographical locations, with countries such as China showing the lowest rates at 0.57 cases per 100,000 under-18 year olds per year, while other countries, such as the United Kingdom, have shown rates that are 30 times higher. Finland and Sardinia, Italy have shown the highest rates, which have been reported to be 100-fold higher than those reported in China. Also, migrating populations tend to adopt the new incidence rates of that country. An example would be a study conducted on children of Asian backgrounds living in the UK, which showed that they exhibited incidence rates that were closer to those shown by long time residents of the UK compared to rates in Asia. This again suggests the effect of environmental factors on incidence rates of T1DM. There are three distinct reasons that have been observed which confirm the presence of environmental factors affecting the incidence of T1DM. The first is that monozygotic twins are not always both afflicted with diabetes, although they are genetically identical. In fact, only 13-33% are both concurrent for the disease. The second reason is that the worldwide rising rates of incidence are too rapid to be caused by genetic changes within populations. Although high risk HLA genotype proportions have decreased while low risk ones have increased, there is still a significant rise in the incidence of T1DM, suggesting environmental pressures are acting on the disease. The third, as previously mentioned, is that immigrants’ risk of incidence will shift towards their new country in as little as one generation.