Diabetes Mellitus, often simply referred to as “diabetes,” is a metabolic disorder that affects millions of Americans. Those with this condition produce no insulin, cannot produce enough insulin, or cannot properly utilize the insulin they do produce. This lack of available or useful insulin causes chronic and dangerously high blood sugar levels, resulting in tissue damage, organ failure, and even death when not properly controlled.

Type 1 Diabetes

Diabetes mellitus comes in two flavors: type 1 and type 2. Both types can be passed on genetically, however it is much more commonly the case in type 1. Type 1 diabetes also has two flavors: idiopathic (no known cause) and immune-mediated.

The majority of Type 1 diabetes cases are immune-mediated, resulting from the immune system’s destruction of insulin-secreting beta cells within the pancreas. This form of diabetes is also known as “child-onset diabetes” due to its tendency to first appear in childhood. In addition to a genetic cause, it is also believed that certain viral infections can contribute to its development.

Type 2 Diabetes

By far, the most common form of diabetes, type 2 diabetes (also called “adult-onset diabetes”) is caused by insulin resistance. This is a condition where cells have become desensitized to insulin and as a result cannot efficiently absorb glucose from the blood. Type 2 diabetes is also strongly linked to genetics as it tends to run in families. However, the relatively recent obesity epidemic and its strong correlation with the development of type 2 diabetes, led to the discovery of several other risk factors.

Insulin Resistance

Normally soon after we eat a meal, our blood sugar levels rise slowly as more glucose is absorbed. This triggers the release of insulin, which is then used to help cells take up the circulating glucose. Meals high in sugar and simple carbohydrates (the main components of most all junk foods) cause blood sugar levels to rise sharply. This sharp rise takes the pancreas by surprise, which starts wildly pumping out insulin in order to deal with the excessive amount of glucose.

Eventually all the glucose gets absorbed, leaving much of the secreted insulin left over. This excess insulin, when present from habitually eating unhealthy foods, causes cells to become desensitized to it. This condition is considered insulin resistance and creates the slippery slope leading to diabetes.

Other Causes of Insulin Resistance

It has also recently been discovered that excess fat (abdominal fat, particularly) can cause muscle and liver cells to become desensitized to insulin. The cells which make up muscles and the liver use a large portion of glucose consumed in the diet and as such can greatly contribute to the development of diabetes once they become insulin resistant.

Other Risk Factors for Type 2 Diabetes

Developing type 2 diabetes has also been associated with ethnicity as African Americans, Native Americans, Hispanic Americans, and Japanese Americans (are you seeing the trend?) are more likely to acquire the condition. Things like high blood pressure, high blood triglyceride (fat) levels, high alcohol intake, a sedentary lifestyle, being overweight or obese, and increasing age also increase the risk for developing type 2 diabetes.

Sources:
http://diabetes.niddk.nih.gov/dm/pubs/insulinresistance/
http://www.emedicinehealth.com/diabetes/page2_em.htm
http://diabetes.webmd.com/guide/diabetes-causes
http://www.umm.edu/endocrin/diabmel.htm