In diabetes, there is too much of the simple sugar glucose in the blood. Certain types of diabetes results from the pancreas being unable to secrete the hormone insulin. When patients with this type of diabetes do not get get insulin for and extended period, they can develop a condition known as ketoacidosis. As the name implies, ketoacidosis results in the body becoming too acidic, which corresponds to a low pH.
Types 1 Diabetes
Normally, the pancreas secretes the hormone insulin to keep blood glucose from becoming too high. Insulin signals cells to take glucose out of the blood and use it for energy or fat storage. In type 1 diabetes, the body's own immune system attacks the insulin-secreting cells of the pancreas and destroys them. Because the pancreas can no longer secrete significant amounts of insulin, insulin levels are low and blood sugar levels are high in type 1 diabetes.
Type 2 Diabetes
Rather than pancreatic destruction, type 2 diabetes begins with insulin becoming less effective at removing glucose from the blood, a condition known as insulin resistance. At first, the pancreas is able to simply secrete more insulin to compensate for this insulin resistance. Unfortunately, high insulin levels themselves cause increased insulin resistance, so insulin resistance keeps increasing. Eventually, the pancreas can no longer secrete enough insulin to compensate for the increased insulin resistance, resulting in type 2 diabetes.
Early Versus Late Type 2 Diabetes
In the early phases of type 2 diabetes, the levels of both insulin and glucose in the blood are high. As insulin resistance keeps increasing, however, eventually the cells of the pancreas become exhausted by their attempts to keep secreting more and more insulin. These exhausted cells die, and the pancreas is no longer able to secrete any insulin at all. At this point, type 2 diabetes becomes essentially identical to type 1 diabetes from the perspective of requiring insulin injections.
Ketone Bodies
Because type 1 and late-stage type 2 diabetics can no longer make their own insulin, they require injections of insulin to get glucose out of their blood and into their cells, where it can be used for fuel. If they do not get insulin, or do not get enough insulin, their cells must find something else to use as a source of energy. Ketone bodies are derived from the breakdown of fat and are one such alternative source of energy.
Ketoacidosis
Ketone bodies produce acid byproducts when they are metabolized for energy. When ketone bodies are used extensively for fuel, as can happen when type 1 or late-stage type 2 diabetics do not get insulin, these acid byproducts can build up in the blood to the point where they significantly lower the body's pH. Low blood pH is extremely dangerous and can result in coma if it becomes too severe. Diabetic ketoacidosis is an emergency that requires immediate medical attention.
References
- "Medical Physiology"; Walter F. Boron and Emile L. Boulpaep (eds).; 2003
- "Harrison's Principles of Internal Medicine 16th ed."; Dennis L. Kasper, et al. (eds.); 2005
