Etiology of type-2 diabetes

Type-2 diabetes begins with the development of insulin resistance, due to a combination of family history, an unhealthy lifestyle, aging and other life events.  At this stage, insulin is produced by the pancreas in normal  or increased amounts in an attempt to keep glucose levels near normal. 

In those with a highly resilient pancreas, this increased insulin secretion can continue indefinitely.  In some people, the pancreas is unable to keep up with the workload, and glucose levels rise just above normal.  This is the PREDIABETES phase.

Over time, the combination of high glucose (which is toxic to the beta cells) and chronic overwork, causes the insulin-producing cells to die off faster than they can be replaced, and insulin production wanes.  Glucose levels rise higher, and the classic symptoms of diabetes usually develop: weakness and/or tiredness, extreme thirst—dehydration, increased urination, blurry vision. 

There are several risk factors for type-2 diabetes which include a combination of lifestyle and inherited factors. They include:

Genetics

Obesity

Lack of exercise

Ethnicity (African American, Native   American, Hispanic)

History of PCOS or Gestational Diabetes

Having had a child > 9 lbs at birth

Those with significant inherited risk must take extreme caution to manage lifestyle factors aggressively in order to avoid developing type-2 diabetes.