Insulin resistance has been linked to diabetes, hypertension, dyslipidemia and
cardiovascular disease. Obesity is a common thread among metabolic disorders (Reilly an Rader 2003) as well as cardiovascular disease (Haffner 1997; Lempiainen, Mykkanen et al. 1999) and is associated with insulin resistance.(Goodpaster, Thaete et al. 1997) In addition to generalized obesity by either body fat or body mass index (BMI) criteria, insulin resistance is also associated with the distribution of body fat, including abdominal visceral fat (Goodpaster, Thaete et al. 1997) and fat accumulation within skeletal muscle.(Goodpaster, Thaete et al. 2000) There is also increasing evidence that impaired capacity for fat oxidation in obesity and type 2 diabetes is related to insulin resistance (Kelley, Goodpaster et al. 1999) Thus, the metabolic disturbances of insulin resistance and type 2 diabetes appear to be more global to include dysregulated fat metabolism as well as impaired glucose metabolism.
The alarming increase in obesity in the U.S. (Mokdad, Ford et al. 2003) and around the world (Hernandez, Cardonnet et al. 1987; al-Isa 1995; Hodge, Dowse et al. 1995; Flegal, Carroll et al. 1998; Arroyo, Loria et al. 2000) is a paramount public health concern affecting children, middle-aged and older men and women across a variety of ethnic and racial groups. The increase in obesity has led to a marked increase in the metabolic syndrome (Ford, Giles et al. 2002) creating additional risks for type II diabetes and cardiovascular disease. Data from the Framingham study have established an increased incidence of cardiovascular events with increasing weight (Hubert, Feinleib et al. 1983; Colditz, Willett et al. 1995) and weight gain was a significant risk factor for development of diabetes. The association of obesity with the insulin resistance syndrome is not only related to the degree of obesity but is dependent on body fat distribution. Thus, individuals with greater degrees of central adiposity develop this syndrome more frequently than do those with a peripheral body fat distribution.(Kissebah and Krakower 1994).