In the UK, there are 90% of people diagnosed with diabetes are Type II diabetes and approximately 10% of people diagnosed with diabetes are Type I diabetes.
The exact cause of Type I diabetes is not fully understood. It is characterised by complete insulin deficiency. The body’s own immune system of individual with Type I diabetes attacks and destroys the insulin-secreting pancreatic beta cells but we do not know what initiates the autoimmune beta-cell destruction. Other possible factors include genetics and environmental factors. Twins and family studies proved that the chance of developing diabetes escalates with the number of family members diagnosed with the condition. Environmental factors also believed to have effects on the risk of Type I diabetes such as exposure to viruses, bacteria or chemicals2. As consequences of body’s inability to produce insulin, follow by the building up of blood glucose that exceeds renal threshold, resulting in frequent urination (especially at night) due to osmotic diuresis. The loss of fluid and electrolytes from body through urination leads to increased thirst3. Besides, people with Type I diabetes often feel tired as their body cells are deprived of glucose. Other presenting symptoms include unintended weight loss, blurred vision, recurrent thrush, cuts and grazes that do not heal4, skin infections and muscle loss through breaking down of protein2.
The contributing factors of Type II diabetes are genetics, environmental factor or lifestyle such as inactivity or obesity where these factors give rise to the body to develop insulin resistance or insufficient insulin production to maintain normal blood glucose level. Patients who have identical twins that are diagnosed with Type II diabetes have chance more than 50% to develop diabetes. Environmental factor such as poor nutrition during early life can impede beta cells development and functions, thus increases susceptibility to diabetes in later life5. It still needs clarifications upon the events that lead to beta cells dysfunction and insulin insensitivity in Type II diabetes. The symptoms may take a long time to develop and not always obvious. It is unsurprising that people can have Type II diabetes without realising it over a long period of time6. The symptoms are pretty much the same as the symptoms of Type I diabetes such as peeing more than usual (especially at night), increased thirst, fatigue and blurred vision. People with Type II diabetes do have gradual and insidious onset of illness or hyperosmolar hyperglycaemic state. Frequent infections such as recurrent thrush or slowly healing cuts and grazes are also the symptoms because Type II diabetes affects the body’s ability to recover and resist infections6.After the fasting for 8-12 hours, the blood glucose level of a non-diabetic individual is low which is lower than 6.1 mmol/L2. The early phase peak appears within the first 15-30 minutes after the consumption of glucose is accountable for the initial rise in blood glucose level upon glucose absorption into the blood7. Pancreatic insulin secretion takes place in response to the rising blood glucose. The glucose is absorbed from the gastrointestinal tract within 30-60 minutes of consumption. The blood glucose level reaches the peak after approximately 60 minutes8. Thus, an elevation in blood glucose level is detected by the pancreatic beta cells, stimulating them to release insulin into the blood, also encouraging the inhibition of glucagon secretion from the pancreatic alpha cells. The insulin secretion and glucagon inhibition are aimed to reduce blood glucose to baseline fasting level7. It stimulates the uptake of blood glucose into the body cells including adipose, liver and muscle cells. The insulin binds to insulin receptors located on the cell membrane, promoting increase of number of glucose transporters. The glucose then enters cells through the specific glucose transporters such as GLUT-4 which is found on muscle and fat cells. Consequently, the blood glucose level drops as a result of increased glucose transported into cells. Besides, the insulin promotes glycolysis which breaks down glucose for cellular energy. Glycogenesis, a process that produces glycogen for storage from the conversion of glucose takes place by stimulation of insulin. In addition, insulin triggers the inhibition of lipolysis, a process involving breaking down of body lipid. All these events contribute to an elevation in glucose usage and storage9. Therefore, the blood glucose level at 1-2 hours interval decreases gradually along with the actions and effects of insulin. The stimulation of insulin secretion diminishes accompanied by the reduction blood glucose7. The blood glucose level of non-diabetic individual returns to normal within 2 hours of glucose intake. It remains constant or fluctuates in a very small range at time interval 2-3 hours due to the blood glucose homeostatic control process which involves glucose production and glucose combustion. At this stage, glucose is produced through glycogenolysis and gluconeogenesis stimulated by the glucagon released from pancreatic alpha cells, whilst the amount of glucose made from these processes is equivalent to the amount of glucose eliminated from the body at rest8.