Relationship between genetic susceptibility, obesity and the development of type 2 diabetes
In this assignment I will focus on the relationship between genetic susceptibility, obesity and type 2 diabetes. Type 1 diabetes is caused predominantly by the autoimmune destruction of the insulin- producing β-cells of the pancreatic islets, whilst type 2 diabetes results from both impaired insulin secretion and resistance to the action of insulin (Dougherty and Lister, 2011). Diabetes is a major global health problem and in 2010 was estimated to affect 285 million individuals worldwide. This figure is projected to rise to more than 400 million over the next two decades as a result of changing population demographics, such as ageing and urbanization, and changes in lifestyle, such as diet and exercise, and the associated increase in obesity (Holt and Hanley, 2012)
Epidemiology is the study of patterns, causes and effects of disease in a population. Type 2 diabetes is more common in developed countries. (Fehily, 1999). The population of obese individuals has gone up rapidly every year (Knight, 1984). During the past few decades, diabetes has gone up in many parts of the world and this is associated with increasing obesity (Fehily, 1999).
Obesity is a condition of being overweight and is defined clinically by a body mass index (BMI). (Prentice and Jebb, 2003). Body mass index is the weight in kilograms divided by the height in meters squared (NHS choices, 2012). The desirable BMI is in the range of 18.5 – 24.9, overweight is 25 – 29.9 clinically obese is 30 – 35.9 and morbidity obese is 36.0 and over (World Health Organization, 1998).
The massive explosion in obesity rates worldwide has largely been responsible for the increase in diabetes. It is estimated that up to 80% of new cases of diabetes can be attributed to obesity. In the UK, the BMI of a person with type 2 diabetes is 30.0 kg/m2 , whilst in the USA 67% of those with type 2 diabetes have a BMI of greater than 27 kg/m2 and 46% have a BMI greater than 30 km/m2 (Holt and Hanley, 2012). The risk of developing type 2 diabetes increases across the whole range of BMI, so that the risk in a middle-aged woman whose BMI is greater than 35 kg/m2 is 93.2 times greater than in a woman whose BMI is less than 22.5 kg/m2. Similar changes are seen in men.
In addition to adiposity, the distribution of fat is also important. For any given level of obesity, the more visceral fat an individual has, the greater their risk of developing diabetes. This is reflected clinically by a waist measurement. For men, waist circumference of less than 94 cm is low, 94–102 cm is high and more than 102 cm is very high. For women, waist circumference of less than 80 cm is low, 80–88 cm is high and more than 88 cm is very high (National Institute for Health and Clinical Excellence, 2006).
The most important environmental factors for diabetes are obesity and physical inactivity. The striking increase in the prevalence of obesity...