AIMS/HYPOTHESIS: The aim of this study was to examine the possible link between isolated post-challenge hyperglycaemia (2-h post-challenge plasma glucose >/= 11.1 mmol/l, and fasting plasma glucose < 7.0 mmol/l) and mortality. METHODS: The data from three population based longitudinal studies (in Mauritius, Fiji and Nauru) were pooled and mortality rates were determined in 9179 people who were followed for between 5 and 12 years. RESULTS: There were 595 people with previously diagnosed diabetes, and 799 with newly diagnosed diabetes, of whom 243 (31) had isolated post-challenge hyperglycaemia. In comparison with people without diabetes, people with isolated post-challenge hyperglycaemia had an increased risk of all-cause mortality [Cox proportional hazards ratio (95 % CI): 2.7 (1.8-3.9) - men; 2.0 (1.3-3.3) - women], and of cardiovascular mortality [2.3 (1.2-4.2) - men; 2.6 (1.3-5.1) - women]. In addition, men with isolated post-challenge hyperglycaemia had a high risk of cancer death [8.0 (3.6-17.9)]. CONCLUSION/INTERPRETATION: These data show that isolated post-challenge hyperglycaemia, which can only be identified by the 2-h glucose, is common, and at least doubles the mortality risk. This should be considered in the design of screening programmes that use only fasting glucose.