Complications of Diabetes and Role of Insulin Resistance in Metabolic Syndrome

Zachary T. Bloomgarden, MD, MACE: We somewhat arbitrarily have divided the complications of type 2 diabetes into 2 groups: microvascular—referring to small vessel abnormalities [such as] diabetic neuropathy, diabetic retinopathy, and diabetic nephropathy; and macrovascular—referring to atherosclerotic cardiovascular disease. These are the major complications of diabetes and affect a huge proportion of individuals with the disease.

We understand type 2 diabetes as representing the intersection of both genetically and environmentally determined patient characteristics. One is insulin resistance—decreased action of insulin at its receptor. That is caused by the environment, namely obesity, lack of physical activity, and a number of genetic factors, as well.

Then, [another characteristic is] reduction in the insulin secretory response to various stimuli, and this is probably primarily a genetic factor. So, in this context, the insulin secretory effect is not directly related to the other aspects of metabolic syndrome. But metabolic syndrome is essentially a constellation of abnormalities that are all related to insulin resistance. This is what seems to be the central actor that leads to hypertension, that leads to a certain form of dyslipidemia caused by obesity (particularly abdominal obesity), which then leads to the concurrence of diabetes with the other cardiovascular risk factors.