The APPENDIX section contains a complete list of centers that participated in the EURODIAB IDDM Complications Study.Abbreviations: AER, albumin excretion rate; CHD, coronary heart disease; CV, coefficient of variation. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Relationship Between Plasma Sialic Acid Concentration and Microvascular and Macrovascular Complications in Type 1 DiabetesThe EURODIAB Complications StudyOBJECTIVE -To test the hypothesis that an increased plasma concentration of sialic acid, a marker of the acute-phase response, is related to the presence of diabetic micro-and macrovascular complications in type 1 diabetes. RESEARCH DESIGN AND METHODS -We investigated the relationship betweenplasma sialic acid concentration and nephropathy, retinopathy, neuropathy, and coronary heart disease (CHD) in a cross-sectional survey of 1,369 people with type 1 diabetes. Subjects were participants in the EURODIAB IDDM Complications Study, which involved 31 centers in 16 European countries.RESULTS -There was a significantly increasing trend of plasma sialic acid with severity of retinopathy (P Ͻ 0.001 in men) and with degree of urinary albumin excretion (P Ͻ 0.001 men, P Ͻ 0.01 women). Plasma sialic acid correlated with increasing plasma creatinine concentration (P Ͻ 0.009 men, P Ͻ 0.0002 women), and men with neuropathy had a higher plasma sialic acid concentration than those without (P Ͻ 0.006). There was no significant correlation between plasma sialic acid and CHD in either sex. Elevated plasma sialic acid concentrations were also associated with several risk factors for diabetic vascular disease: diabetes duration, HbA 1c , plasma triglyceride and cholesterol concentrations, waist-to-hip ratio, hypertension and smoking (in men), and low physical exercise (in women). In multiple logistic regression analysis, plasma sialic acid was independently related to proliferative retinopathy and urinary albumin excretion rate in men.CONCLUSIONS -We conclude that an elevated plasma sialic concentration is strongly related to the presence of microvascular complications in type 1 diabetes, especially retinopathy and nephropathy. Further study of acute-phase response markers and mediators as indicators or predictors of diabetic microvascular complications is therefore justified.