What Is Diabetes Mellitus?

Diabetes mellitus is a disease characterised by low blood sugar. There are two main types of diabetes, types 1 and 2, which differ in their cause and pathophysiology. Type 1 diaetes is caused by the autoimmune destruction of pancreatic ? cells, the main function of which is to produce the hormone insulin. The role of insulin is to facilitate movement of glucose from the blood to body cells. In the absence of insulin, this movement is severely reduced resulting in the majority of glucose remaining in the blood, thus producing the characteristic high blood glucose observed in diabetics. As a consequence of this, the concentration of intracellular glucose is therefore lower than it should be, forcing the mitochondria in the cell to use fatty acid, rather than glucose to produce ATP during respiration. A consequence of this is the production of ketone by-products, which leads to ketoacidosis (low blood pH). This is just one example of altered intracellular and extracellular physiology that results from the respective altered glucose concentrations (Watkins 1998). While the consequences of type 2 diabetes are also high blood glucose and low cellular glucose, the cause is different to that of type 1 diabetes. In type 2 diabetes, the number of pancreatic ? cells is not reduced. Instead, there is a down regulation of insulin receptors, which reduces the efficiency of glucose transport from blood to cells. So while the production of insulin is not affected, the rate and efficiency in which it can act is reduced, resulting in less glucose being transported from blood to cells. Again, the result of this is low cellular glucose concentrations and high blood glucose levels. It is this type of diabetes that often occurs as a result of poor diet and lifestyle and can often be reversed through rectification of these contributing factors (Watkins 1998). Diabetes is a significant worldwide health issue, with around 7% of the world's population believed to be diabetic as of 2004, accounting for around 200million people worldwide. While deaths have decreased dramatically in the last 50 years due to better treatments, diabetes is a problem that is set to worsen in the coming decades, particularly in the developed world where obesity is on the increase and lifestyles are becoming increasingly sedentary (Williams and Pickup 2004).