The Effects of Exercise on Adipokine in Impaired Fasting Glucose or Impaired Glucose Tolerance Patients

Backgrounds: Type 2 diabetes mellitus can be caused by genetic and environmental factors. Type 2 diabetes could be prevented by modifying the environmental risk factors such as physical inactivity, heavy eating, and obesity. It is reported that regular physical training could prevent the progression of diabetes from prediabetes such as impaired glucose tolerance (IGT) and impaired fasting glucose (IFG).

Prediabetes, the term of IGT and IFG, could progress to type 2 diabetes in 30~40 % within 4~5 years. Moreover, cardiovascular and cerebrovascular events are increased in prediabetic patients like as type 2 diabetic patients.

Adipose tissue is thought as a endocrine organ that secrets and regulates various hormones known as adipokines including adiponectin, resistin, leptin, visfatin, tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), and retinol-binding protein 4 (RBP 4). Recently, many adipokines are thought that related with metabolic disturbance such as glucose intolerance, dyslipidemia, and insulin resistance.

Adiponectin is known as anti-diabetic factor exerting actions on muscle fatty acid oxidation and insulin sensitivity. Plasma adiponectin levels are significantly decreased in obese, type 2 diabetes, and insulin resistant patients and correlated with insulin sensitivity. Also, adiponectin has anti-inflammatory and anti-atherogenic effects. So, adiponectin is representative insulin sensitivity marker and may be a protective factor against development of type diabetes. In previous data, there was discrepancy in effects of exercise on adiponectin levels. Some study showed exercise interventions could not have effects on adiponectin levels. However, other study suggested that physical fitness may increase adiponectin levels in obese insulin resistant adults.

RBP-4, secreted by adiocytes, has effects on reducing glucose transporter 4 (GLUT 4) in adipocytes or increasing gluconeogenesis enzyme activity such as PEPCK in the liver. Also, it is known that RBP-4 is elevated in insulin resistant patients such as type 2 diabetes and obesity. After exercise training, RBP-4 levels were decreased in subjects with improvements of insulin resistance.