Obesity, insulin resistance and isolated low high-density-lipoprotein cholesterol in Chinese subjects

Recent studies have shown that the risk of developing coronary heart disease in subjects with 'isolated low high-density-lipoprotein cholesterol (HDL-C)' (defined as HDL-C < 0.9 mmol/l and total cholesterol (TC) < 5.2 mmol/l) was similar to those with hypercholesterolaemia. We examined the prevalence of isolated low HDL-C in Hong Kong Chinese and its relationship with insulin resistance and triglyceride (TG) level.

Hong Kong Chinese subjects (n = 1493) recruited in a population-based prevalence survey for cardiovascular risk factors were examined. Insulin resistance was calculated using a computer-solved homeostasis model assessment method.

Of the 1493 subjects, 72 (4.8%) had isolated low HDL-C, in whom half (n = 36) had TG > or = 1.7 mmol/l and half (n = 36) had TG < 1.7 mmol/l. Compared with the 'controls' (subjects with TC < 5.2 mmol/l and HDL-C > or = 0.9 mmol/l; TC > or = 5.2 mmol/l and HDL-C < 0.9 mmol/l; or TC > or = 5.2 mmol/l and HDL-C > or = 0.9 mmol/l, n = 1421), subjects with isolated low HDL-C and high TG were more obese, had higher plasma glucose, fasting and 2 h plasma insulin concentrations and insulin resistance. Subjects with isolated low HDL-C and TG < 1.7 mmol/l had similar insulin concentrations and insulin resistance, but were more obese than the 'controls'. Subjects with isolated low HDL-C and high TG also had higher fasting PG, insulin and insulin resistance than those with isolated low HDL-C and low TG.

In this population-based study, 4.8% of Hong Kong Chinese had isolated low HDL-C, which was closely associated with obesity. The coexistence of high TG suggests an insulin-resistant state.