The C57BL/6J Mouse as a Model of Insulin Resistance and Hypertension
While diabetes has long been known to be a risk factor for cardiovascular disease, we are only beginning to recognize the risks associated with elevated glucose and insulin levels in nondiabetic patients. Reaven (1988) described the existence of a constellation of metabolic abnormalities that seemed to occur together and to be related to the etiology of cardiovascular disease. He termed this clustering of anomalies “syndrome x” and deﬁned it as the coexistence of hyperinsulinemia, hyperlipidemia, and hypertension in non-diabetic individuals. Together, these features were seen as risk factors for both cardiovascular disease and type 2 diabetes (Reaven, 1988). When intra-abdominal obesity was later included as a risk factor, Bjorntorp (1993) suggested the term “metabolic syndrome”. More recent research has shown that increased fasting insulin, increased fasting glucose, and elevated hemoglobin A1c (HbA1c) all predict both the development of type 2 diabetes and cardiovascular disease. It has been suggested that the “metabolic syndrome” be called the “civilization syndrome” because the various metabolic components of the syndrome, as well as clinical diabetes, are coincident with lifestyle changes associated with Western urbanization (Bjorntorp, 1993). In addition to decreased exercise and increased caloric intake, the epidemiological observations provide evidence that the development of insulin resistance and type 2 diabetes is related to fat consumption and negatively related to carbohydrate consumption (Feskens et al., 1990; King et al., 1984; Marshall et al., 1991).