Objective: To analyse differences in the prevalence of prediabetes (PD), undiagnosed diabetes (UDD) and diagnosed diabetes (DD) and associated factors between Brazilian and English older adults. Design: Cross-sectional study. Setting: England and Brazil. Participants: 5301 participants of the English Longitudinal Study of Ageing study and 1947 participants of the Brazilian Longitudinal Study of Aging study classified as non-diabetics, PD, UDD and DD. Results: The prevalence of PD, UDD and DD was 48·6, 3 and 9·6 % in England and 33, 6 and 20 % in Brazil. In England, the increase in age, non-white skin colour, smoking, general obesity and abdominal obesity were associated with PD, UDD and DD, whereas hypertriglyceridaemia, low HDL levels, hypertension and stroke were associated with UDD and DD. In Brazil, the increase in age was associated with DD and UDD, non-white skin colour and smoking were associated with UDD and abdominal obesity and hypertriglyceridaemia were associated with all three conditions. CVD in England and schooling in Brazil were associated with PD and DD. A sedentary lifestyle was associated with DD in both samples. Conclusions: The prevalence of diabetes was higher in the Brazilian sample. Different associated factors were found in the two samples, which may be related to differences in nutritional transition, access to healthcare services and the use of such services.