The Etiology of Diabetes

The etiology of diabetes is only partially understood. The etiology of a disease is the "cause" of the disease, the pathological factor or process which leads to the symptoms and signs associated with that disease. While we do not understand all the details of how or why diabetes develops in most people, we do understand some of the features of the etiology of diabetes, the basic pathological processes that occur in the body and result in the disease as we know it.


Type I and Type II diabetes are quite different diseases in etiology. While their resulting features have much in common, such as hyperglycemia (high blood sugar), they have many differences and their underlying cause is probably quite different.

Type I Diabetes

Type I (also often referred to as juvenile onset or insulin-dependent diabetes) is most common to present in childhood, although it can occur at any age. It is the less common form of diabetes. What is known about the etiology of Type I diabetes is that it appears to be due to an autoimmune disease. An autoimmune disease occurs when the immune system (which normally fights disease) goes haywire, attacking and damaging cells and tissues of the body. There are many types of autoimmune diseases (from multiple sclerosis to Graves' disease) and the factor that sets them off in the first place is generally poorly understood. However, once the autoimmune attack starts in diabetics, the cells of the pancreas that normally produce insulin are damaged. The body is no longer able to produce insulin in adequate levels and high blood sugar and all the symptoms and effects of diabetes follow. Although this is fairly well agreed upon as the etiology of Type I diabetes, the initial inciting factor or factors that determines if someone is going to develop the disease is not understood.

Type II Diabetes

Type II diabetes appears to be an even more complicated picture. The etiology of diabetes of this type is unclear and may vary from patient to patient. On the one hand, some patients appear to have decreased levels of insulin secretion, similar to Type I. Others have relatively normal insulin levels but the body's peripheral response to insulin is lower than normal (termed insulin resistance). These both appear to be important etiologies in the development of Type II diabetes, either alone or in concert. It is unclear what causes these problems in the first place but, because family history and ethnicity are strong risk factors of diabetes, there may be a strong genetic component. Also, obesity is though to alter the way that fat cells responde to insulin and this may play an important role in the development of insulin resistance.

While the exact cause of diabetes is not known in all cases, the risk factors (such as family history, obesity, advanced age, ethnicity, etc.) are well recognized and people at high risk for Type II Diabetes are often counseled to be on the look out for signs and symptoms of early diabetes and to take steps to reverse those risk factors which can be controlled (such as weight loss, exercise, dietary changes, etc.).