The prevalence of type 2 diabetes varies greatly by ethnic group within and across countries. The most reliable data on the prevalence of diabetes are based on two hour plasma glucose values after an oral glucose tolerance test,1 which is currently the gold standard epidemiological and clinical diagnostic test for diabetes and impaired glucose tolerance. In Newcastle, England, on the basis of clinical evidence and oral glucose tolerance test results, about 20% of British South Asians had diabetes, compared with only 4% of white Europeans, after age adjustment in a sample of 25-74 year olds.2 Might such observed differences in prevalence, at least in part, be artefacts of the diagnostic method?

In 1965, the World Health Organization expert committee drew attention to the “lack of suitable epidemiological information about glucose tolerance in various populations of various races and cultures in different countries”3 and highlighted the need for research in different populations. The call was repeated in 1980,1 with special reference to the oral glucose tolerance test and the dose of glucose, with 75 g …