oType 1 diabetes is entirely due to an almost complete deficiency of insulin. The deficiency is the result of the immune system erroneously attacking and destroy- ing the insulin-producing cells in the pancreas. For the proper functioning of our bodies, it is neces- sary for insulin to be present at all times in the bloodstream and tissues, not only after we have eaten. Insulin is essential to maintain the structure of our tissues and prevent them from being broken down in an uncontrolled manner. Without any insulin present, our tissues literally melt away into simple compounds that leave our bodies when we urinate. Accordingly, people with type 1 diabetes have high levels of sugar and breakdown products of fat and protein in the bloodstream and urine and develop the typical symptoms.
Type 2 diabetes is due to a combination of our body tissues becoming resistant to the action of insulin (for the reasons described previously in Question 1) and the inability of the pancreas to make enough extra insulin to overcome it. Although this latter compo- nent of the problem is often viewed as a failure of the pancreas, it is not true in the strictest sense. While it is common for the insulin-producing capability of the pancreas to decline throughout later adult life, it was nevertheless sufficient throughout most of human evolution to prevent us from developing diabetes. It is only in recent times, when our lifestyle and envi- ronment have caused many of us to become very insulin resistant, that the insulin-producing capacity is unable to compensate. In the true sense, it fails because we impose an excessive load upon it. This is true, even for those of us who have a hereditary pre- disposition to becoming insulin resistant.