In the whole study population, after adjustment for age, sex, lifestyle factors, fasting status and BMI, raised levels of plasma RBP4 were significantly associated with higher risk of type 2 diabetes; the OR (95% CI) comparing the last quartile against the first quartile was 1.69 (1.09–2.62; P-trend =0.004). Here, RBP4 is linked to type 2 diabetes mellitus.