This cross-sectional study was conducted intermittently in the National Capital District of Papua New Guinea from 1995 to 1999. Fasting capillary blood glucose (FCBG) was used as the screening test for diabetes. Blood glucose level was measured using the standard pocket-size reflectometer. A total of 769 individuals were screened. There were 385 males and 384 females ranging in age from 12 to 76 years. High FCBG (hFCBG) (> or = 7.0 mmol/l) was found in 13% of those examined and was associated with older age (p = 0.001), high body mass index (p = 0.027), coastal region of origin (p = 0.012) and betelnut chewing (p < 0.001). The prevalence of hFCBG in those of highland origin was 9% compared to 16% among the coastal people. Among the Seventh Day Adventists, the prevalence of hFCBG was 10%. The overall prevalence of hFCBG was the same in males and females but in those aged 35 years or more the prevalence was higher in females. Multivariate analysis (logistic regression) showed that hFCBG was significantly associated with betelnut chewing (p = 0.005) and age (p = 0.028); the body mass index (p = 0.061) and region of origin (p = 0.056) associations approached statistical significance. Sex and smoking were not statistically significant factors. In conclusion, diabetes is common in the 'healthy' population of Port Moresby and rates in highlanders living there were surprisingly high. In this study, betelnut chewing was independently associated with diabetes, and may therefore be a risk factor for diabetes mellitus.