['Serum β-2 microglobulin (B2M) level predicts mortality in chronic kidney disease. Glycation of B2M is cytotoxic and may contribute to the risk of mortality in diabetic patients. Our objective was to evaluate the relationship between B2M and mortality in diabetic patients.', 'In this prospective study, 896 participants of the Third National Health and Nutrition Examination Survey with diabetes were included in the analysis. Serum B2M level was used in multivariate Cox regression analysis to predict all-cause and diabetes-related mortality.', 'During a median follow-up of 11.8 years (range 0.1-18.2 years) and 9220.5 person/years, 541 (42.4%) and 207 (16.8%) participants died from all causes and diabetes-related causes respectively. One natural-log unit of B2M was significantly associated with all-cause (hazard ratio (HR)=6.53, 95% CI 2.07-20.6) and diabetes mortality (HR=7.35, 95% CI 1.01-53.38) after multivariable adjustment. Similar results were obtained when B2M was analyzed as tertiles or in the threshold model (T1+T2 vs. T3). Examination of regression splines suggests a linear increase in hazard for mortality with increasing B2M levels.'] Does serum β-2 microglobulin predict mortality in people with diabetes?