Insulin sensitivity in Chinese: Inter-relations with obesity and other components of the metabolic syndrome

These studies address the roles of insulin sensitivity and obesity in the metabolic syndrome (MES) in Chinese. No measure of insulin sensitivity suitable for use in cross-sectional studies exists. We modified the short-insulin tolerance test (SITT) and evaluated its safety and efficacy in 11 healthy subjects. Using three intravenous doses of insulin (0.1, 0.05 and 0.01 U·kg-1), plasma glucose concentrations were analysed by standard analyses and by my new analysis. The new analysis was individualised and allowed early termination of the test should hypoglycaemia occur. The 0.1 U·kg-1 dose data analysed by the new analysis gave the most reproducible results.;In young 27 Chinese diabetic patients, the SITT correlated better with variables associated with MES than the intravenous glucose tolerance test and measures derived from fasting insulin and glucose concentrations.;We compared variables from the SITT with known risk factors for MES in healthy 33 Chinese and 31 Caucasian volunteers. The Chinese were significantly less sensitive to insulin than the Caucasians. In addition, the Chinese had significantly higher HbA1c concentrations, although fasting glucose and insulin concentrations did not differ.;The roles of insulin sensitivity and obesity in the clustering of metabolic variables associated with MES were also examined in 145 Chinese subjects. Reduced insulin sensitivity was related dyshpidaemia, hyperglycaemia and central adiposity, independently of age, body mass index and gender, but was not related to hypertension. Visceral and subcutaneous fat had separate metabolic consequences, with only visceral fat affecting diastolic blood pressure, insulin sensitivity and lipid concentrations, while subcutaneous fat was related to increases in non-esterified fatty acids and urate, and decreases in bilirubin concentrations. An exploratory factor analysis of the entire data set suggested that obesity, and not insulin sensitivity, was linking blood pressure, glucose intolerance and dyslipidaemia in these Chinese subjects.;Healthy Chinese may be less sensitive to exogenous insulin than Caucasians and insulin resistance alone may not be responsible for the clustering of metabolic abnormalities in Chinese. Multivariate analysis suggests that obesity links the facets of MES in Chinese, and that those most at risk of developing multiple metabolic derangements are those with insulin resistant obesity.