Ethnic comparisons of the cross-sectional relationships between measures of body size with diabetes and hypertension R. Huxley, W. P. T. James, F. Barzi, J. V. Patel, S. A. Lear, P. Suriyawongpaisal, E. Janus, I. Caterson, P. Zimmet, D. Prabhakaran, S. Reddy and M. Woodward, on behalf of the Obesity in Asia Collaboration* The George Institute for International Health, Sydney, NSW, Australia Address for correspondence: Dr R Huxley, The George Institute for International Health, PO Box M201, Missenden Road, Sydney, NSW 2050, Australia. E-mail: rhuxley@george.org.au Summary Recent estimates indicate that two billion people are overweight or obese and hence are at increased risk of cardiovascular disease and its comorbidities. However, this may be an underestimate of the true extent of the problem, as the current method used to define overweight may lack sensitivity, particularly in some ethnic groups where there may be an underestimate of risk. Measures of central obesity may be more strongly associated with cardiovascular risk, but there has been no systematic attempt to compare the strength and nature of the associations between different measures of overweight with cardiovascular risk across ethnic groups. Data from the Obesity in Asia Collaboration, comprising 21 cross-sectional studies in the Asia-Pacific region with information on more than 263 000 individuals, indicate that measures of central obesity, in particular, waist circumference (WC), are better discriminators of prevalent diabetes and hyper- tension in Asians and Caucasians, and are more strongly associated with prevalent diabetes (but not hypertension), compared with body mass index (BMI). For any given level of BMI, WC or waist : hip ratio, the absolute risk of diabetes or hypertension tended to be higher among Asians compared with Caucasians, supporting the use of lower anthropometric cut-points to indicate overweight among Asians. Keywords: Diabetes, ethnicity, hypertension, obesity. obesity reviews (2008) 9 (Suppl. 1), 53–61 Introduction There are few countries that remain unaffected by the global epidemic of overweight and obesity, such that the number of overweight (1.6 billion) (1) or obese (400 million) (1) individuals now exceeds the number of those who are underweight. Excess weight is associated with an array of adverse health consequences that include cardio- vascular, endocrine, inflammatory, mechanical diseases and psychosocial disease states; hence, the timely identification of high risk individuals is an important priority in primary health care (2–4). Past methods to define excess weight using body mass index (BMI) have largely been based on data derived from predominantly Caucasian populations (5). However, whether this method can be generalized to non-Caucasian populations has been questioned, because of potential ethnic differences in the strength of the associations between obesity and cardiovascular risk factors (6). In turn, this has prompted the suggestion that there should be ‘ethnic-specific’ cut-points for overweight and obesity – although what values these should assume remains a matter of debate. *Members listed in acknowledgements. obesity reviews 53 © 2007 The Authors Journal compilation © 2007 The International Association for the Study of Obesity. obesity reviews 9 (Suppl. 1), 53–61