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An association between hypertriglyceridemia, obesity, hyperinsulinemia, insulin resistance, impaired glucose
tolerance, hypertension, and coronary artery disease (CAD) has been appreciated since the early 1960s (1-4). Various aspects of this syndrome have been called syndrome X (5), the metabolic syndrome (6), the insulin resistance syndrome (7), and the atherogenic lipoprotein phenotype (8). The various lipoprotein abnormalities that occur with hypertriglyceridemia in this syndrome and the potential mechanisms for this dyslipidemia are the focus of this article.
Abbreviations: apo, apolipoprotein: CAD, coronary artery disease; CETP, cholesteryl ester transfer protein; LPL, lipoprotein lipase.
A table elsewhere in this issue shows conventional and Systeme International (SI) units and conversion factors for many substances.
This article is based on a presentation at a conference organized by the Indiana University Diabetes Research and Training Center. The conference and the publication of this article were made possible by an unrestricted educational grant from Eli Lilly and Company
CENTRAL OBESITY - J. Vague (9) first documented central obesity as an adverse health factor in the early 1950s when he described the android and gynoid forms of obesity Kissebah et al. (10) and Bjorntorp and colleagues (11) rekindled interest in abnormalities of body fat distribution when they noted that central obesity was associated with increased risk of diabetes and CAD in both men and women.
With the advent of computerized tomography, a preponderance of intraabdominal obesity, in contrast to subcutaneous fat accumulation, was demonstrated in individuals with central fat accumulation (12-15). Although intra-abdominal fat correlated with subcutaneous fat and total body fat, when all fat stores are considered simultaneously, only intra-abdominal fat remains correlated with the other components of the central obesity-insulin resistance syndrome (16). Indeed, even in men with a normal BMI, the amount of intraabdominal fat is correlated with the other components of this syndrome. Although adipose tissue characteristically accumulates in the hips and thighs in women, those who have increased intra-abdominal fat have metabolic abnormalities similar to those of centrally obese men (10,11,17).
CENTRAL OBESITY AND INSULIN RESISTANCE - Hyperinsulinemia, thought to be due to insulin resistance, was noted to be associated with obesity shortly after the development of the assay for insulin (2,3). This association was demonstrated to be caused by impaired insulin action (i.e., insulin resistance)...