Changes in the buccal mucosa of 296 Indian and Malay betel-nut chewers in Perak, West Malaysia, were studied clinically. 167 out of 212 Indian subjects incorporated tobacco in their quids, while 45 out of 84 Malay subjects incorporated. "Gambir". The Indians appeared to show a higher proportion of mucosal changes, particularly when tobacco was used. "Gambir" did not appear to be potent in the production of mucosal changes. Comparison with studies in other parts of the world suggested comparable findings with respect to both tobacco and non-tobacco chewing samples, and there would appear to be some evidence that tobacco-containing quids are likely to produce a higher proportion of mucosal changes as compared to non-tobacco-containing quids. An attempt to demonstrate a dose-effect relationship by dividing the subjects into "slight" and "heavy" chewers did not yield significant differences between these two categories in each of the groups.
The prevalence of diabetes in Central America was somewhat greater than in East Pakistan and Malaya, less
than in Uruguay and Venezuela, and substantially less than in affluent societies such as the United States. Differences in prevalence among Central American countries were modest but probably significant in some instances. In all Central American countries diabetes was more common in females but this difference was probably attributable to the greater adiposity of the women. Age-matched populations from eleven different countries of three continents have now been tested using standardized methods. Prevalence of diabetes varied greatly, and differences were more related to environment than to race. These results support the hypothesis that environmental factors can increase or reduce prevalence by several-fold.