LDL SUBCLASS PHENOTYPES AND THE RISK-FACTORS OF THE INSULIN-RESISTANCE SYNDROME

The insulin resistance syndrome is characterized by a constellation of risk factors including obesity, central body fat distribution, hypert ension, glucose intolerance, elevated plasma insulin levels, increased triglyceride and decreased high-density lipoprotein (HDL) cholesterol . Similarly, low-density lipoprotein (LDL) subclass phenotype B, chara cterized by a predominance of small, dense LDL particles, is associatr ed with increased triglyceride and lower HDL cholesterol levels, Both the insulin resistance syndrome and phenotype B have also been related to increased risk of coronary heart disease, Using a sample of nearly 700 women who participated in the Kaiser Permanente Women Twins Study , we investigated the associations of LDL subclass phenotype B with th e risk factors that characterize the insulin resistance syndrome. The results demonstrate that LDL subclass phenotype B was strongly associa ted with both age and diabetes status, Among nondiabetic women, phenot ype B was more prevalent in those with higher body mass index and in t hose with higher waist-hip ratio, In addition to the expected associat ions with triglyceride and HDL cholesterol, mean values of both systol ic and diastolic blood pressure were higher in women with phenotype B. Finally, fasting and post-load insulin levels and post-load glucose l evels were higher in those with phenotype B, In general, these relatio nships persisted in multivariate statistical analyses. Therefore, a pr edominance of small, dense LDL particles appears to be an integral fea ture of the risk factors that characterize the insulin resistance synd rome.