What is it?
Type 2 diabetes is a metabolic disease caused by the developed insulin resistance of cells, and the body’s inability to produce enough insulin to meet it’s needs. Insulin is essential to the movement of glucose from the blood into the cells: hence the disease leads to heightened glucose levels in blood and urine. Typical symptoms include increased thirst, hunger, and need of urination, as well as weight loss and sores that do not heal. Around 6% of the world’s adult population suffer from T2D, and it is particularly common in developed and developing countries.
What causes it?
The risk of developing T2D involves both genetic and environmental factors. The most important is being overweight, and others include lack of exercise, poor diet, smoking, and stress. Genetics play a big role, too – it has been found that if one of identical twins has T2D, the other one has at least a 90% chance of developing it as well. 36 genes have been associated with T2D, but there probably are hundreds of them.
What happens during it?
There are specific glucose transporters in cells whose job it is to create pathways through which glucose can move into cells. Normally these transporters are inside the cell. What insulin does is that it binds to the cell membrane and starts a complex series of reactions, which leads to the glucose transporters moving to the membrane, allowing the influx of glucose. Without the correct functioning of insulin these transporters stay inactive inside the cell, and the glucose remains “trapped” in the bloodstream.
All overweight individuals have insulin resistance, which means that their cells don’t respond to insulin as readily as they do in healthy individuals. It is believed that excess fat around the waist is the primary cause of insulin resistance. This fat leads to a state of chronic inflammation which not only damages the body, but also increases the number of cytokines in the blood. Heightened levels of cytokines and free fatty acids are thought to play a key role in the development of insulin resistance.
T2D occurs, however, only in those whose pancreatic cells cannot compensate for this resistance by producing more insulin. It has been found that the insulin-producing beta cells have diminished both in number and in function in those affected. For unclear reasons, beta cells undergo frequent apoptosis which means that they kill themselves as a result of an external message. On top of this, the cells fail to respond appropriately to heightened glucose levels while responding increasingly to high levels of amino acids and fatty acids.
How can it be treated?
The most effective treatment for T2D is lifestyle intervention. Proper exercise, a healthy diet, and weight loss are highly encouraged. Monitoring of blood sugar and a diet low in carbohydrates are useful to many. If these measures don’t help or the patient isn’t able to maintain a healthy lifestyle, insulin, other medications, and weight loss surgery can be considered.
Sources: https://www.niddk.nih.gov/health-information/health-topics/Diabetes/insulin-resistance-prediabetes/Pages/index.aspx#causes, http://emedicine.medscape.com/article/117853-overview#a3, http://www.medscape.org/viewarticle/483307_4, https://en.wikipedia.org/wiki/Diabetes_mellitus_type_2#Epidemiology