The association between the waist to hip ratio (WHR) and the occurrence of diabetes was assessed among 183 middle-aged Finnish subjects with impaired glucose tolerance (IGT) defined according to the 1985 WHO criteria. As estimated by multivariate logistic regression analysis, the odds ratio of diabetes at the high value of WHR was 8.0 (95% Cl: 2.2-29.4) times as great as that at the low value. The conclusion is that the middle-aged IGT subjects with a high WHR are more prone to diabetes than those with a low WHR.