The role of waist-to-hip ratio (WHR) in the metabolic disturbance of IDDM has not been widely explored. Cross-sectional data from the Epidemiology of Diabetes Complications Study were used to examine the associations between WHR and risk factors for IDDM complications such as lipid or lipoprotein levels, blood pressure and fibrinogen. A total of 586 adults (greater than or equal to 18 years of age) were examined. WHR was calculated as the mean of duplicate waist circumference measurements made at mid-point between the iliac crest and the lower costal margin in mid-axillary line divided by the mean of duplicate maximum hip measures. WHR was positively correlated with total cholesterol, LDL-cholesterol, triglycerides, systolic and diastolic blood pressure and fibrinogen univariately for both sexes. WHR was negatively correlated with HDL-cholesterol. These correlations remained significant after adjustment for age among females and became less strong, although still significant, for males. The independent effects of WHR to these IDDM risk factors, assessed by multiple linear regression, indicated WHR was related to adverse lipid and lipoprotein levels, but not to fibrinogen or blood pressure. These findings underscore the importance of targeting intervention to IDDM individuals who have a high WHR to reduce known risk factors for IDDM complications especially those for cardiovascular disease, and is consistent with the hypothesis that insulin resistance may have a role to play in IDDM complications.