The American Diabetes Association and a working group of the International Diabetes Federation and the World Health Organisation are considering the possibility of lowering the level of fasting glucose for diagnosis of diabetes from 7.8 mM to 7.0 mM (126 mg/dl) and adding a "hyperglycaemia" category (6.1-6.9 mM). This report studied the resulting change in the frequency of diabetes in the French D.E.S.I.R. cohort and evaluated cardiovascular risk factors according to the proposed limits. The frequency of treated diabetes was 1.0% in this cohort of more than 5,000 French men and women 30 to 64 years of age, 0.7% had a fasting glucose > or = 7.8 mM versus 1.6% for the proposed > or = 7.0 mM. Using the new criteria, 3.8% of men and 1.6% of women would be diabetic. For many cardiovascular risk factors, men with fasting glucose > or = 7.8 mM had a significantly higher risk than those in the (7.0-7.7 mM) range, whereas no significant differences were found for women. There were few differences between the (7.0-7.7 mM) and (6.1-6.9 mM) ranges, but highly significant differences were apparent for both sexes between the normoglycaemic (< 6.1 mM) and hyperglycaemic (6.1-6.9 mM) categories. The percentage of men with two or more of ten risk factors increased with fasting glucose: 36% in the normoglycaemic (< 6.1 mM) and 49% in the hyperglycaemic (6.1-6.9 mM) categories; 73% with fasting glucose in (7.0-7.7 mM) versus 90% with fasting glucose > or = 7.8 mM. In women, the corresponding percentages were lower: 26% and 60%, 32% versus 64% respectively. The major increase in cardiovascular risk factors would appear to occur at 6.1 mM, for men, whereas the increase in the combination of risk factors was at the more conservative cut-off of 7.0 mM.