Background: Despite the high prevalence of diabetes, limited information is available about the impact of impaired glucose regulation on the cardiovascular disease (CVD) risk among Middle East populations. Aims: To determine the risk of CVD in an urban Iranian population according to glucose tolerance status. Material and methods: The study population consisted of 1752 men and 2273 women, aged ≥40 yr, free of CVD at baseline. Incident CVD was ascertained over a median of 7.6 yr of follow-up. Results: A total of 340 CVD events occurred (197 in men and 143 in women). At baseline, there was no difference between newly diagnosed and known diabetes regarding the Prospective Cardiovascular Münster (PROCAM) risk score and prevalence of metabolic syndrome in both genders. Applying the 1997 American Diabetes Association (ADA) criteria, compared with those with normal glucose tolerance, after controlling traditional risk factors, hazard ratios (HR) and 95% confidence intervals (95% CI) for CVD in women with known and newly diagnosed diabetes were 3.30 (2.09-5.21) and 1.93 (1.16-3.21) and the corresponding values for men were 1.90 (1.11-3.25) and 1.69 (1.12-2.54), respectively. Impaired fasting glucose or impaired glucose tolerance was associated with 56% increased risk of CVD in women (HR 1.56, 95% CI 1.00 to 2.45), in the age-adjusted analysis, considering the 2003 ADA criteria. Conclusions: All diabetic subjects, whether newly diagnosed or known cases, should receive intensive primary prevention for CVD regardless of risk factors, in particular females with abnormal glucose regulation.