A longitudinal study of 266 adult residents of the Pacific Island of Nauru (1975-1976 and 1982) has shown an annual incidence of noninsulin-dependent diabetes of 1.6 per cent per annum. Factors associated with the subsequent development of glucose intolerance were determined by means of regression techniques. The two-hour, post-load plasma glucose concentration was the factor most consistently associated with subsequent glucose intolerance. Other predictors were found to vary in their importance between the sexes. In males, the fasting plasma triglyceride concentration and blood pressure showed a weaker association, and body mass index was of marginal significance. In contrast, in females, two-hour plasma insulin concentration, plasma uric acid concentration, body mass index, and fasting plasma glucose concentration showed a significant association. These findings are discussed in light of the results of similar studies in other populations.