Unlike the more aggressive form of diabetes, Type 1, where the immune system actively searches out and kills islet cells, in Type 2, the cells die through a long process of overwork and poor waste management. Insulin, as you probably know, is the hormone that plays the important role of getting fuel (glucose) into cells. It’s also involved in the storage of glucose, and in getting glucose out of the bloodstream. This is important because glucose is reactive. Exposing tissues to high blood glucose is like exposing metal to water. Glucose eats away at the tissue as surely as rust does metal. Tissues respond in a variety of surprising ways and these responses are usually bad for us, and lead to the dangerous complications of diabetes.
The likelihood of developing Type 2 diabetes can be assessed years before the onset of the disease by measuring blood glucose levels. Surprisingly, in the early stages of the disease, patients secrete more insulin than normal. This happens because of something called “insulin resistance.” Insulin resistance means that although there is plenty of insulin available, it has lost its ability to do its job efficiently. The pancreas compensates for insulin resistance by secreting more and more insulin, as it tries to help the cells absorb glucose. This in turn stresses the islet cells, and eventually, they begin to die (in part due to pancreatic pollution, the production of waste products that cannot be removed quickly enough). The reasons why people become insulin resistant are being actively researched and I will be talking a lot about them in future posts. Obesity can play a role in this process and prediabetic patients who lose weight show clear evidence of increased insulin sensitivity.
The brain needs glucose constantly to function (even when you are watching TV) so when we aren’t eating and supplying our bodies with glucose via food, our bodies produce glucose from stored materials. This process, called gluconeogenesis, is carried out mainly in the liver. Insulin has a role in this too, since it both promotes the storage of glucose, and inhibits the production of glucose. When the body loses normal insulin function it also loses its ability to inhibit glucose production. This is a really big deal because it means that even if you are being good about your diet, your blood sugar can still be high ,thanks to your liver. In fact,much of the blood sugar that damages your tissues comes from the liver.
Because of the slow onset of Type 2 diabetes, a host of therapies are available. First and foremost is lifestyle change to eat less and exercise more. This is something I will be emphasizing over, and over, and over again because it really works. Really. Second, several classes of drugs are available which increase insulin production or decrease blood glucose levels by promoting glucose storage. Ultimately, when the pancreas loses the ability to produce sufficient insulin, the Type 2 patient joins the Type 1 patient in taking insulin. Finally these two separate diseases meet.