ABSTRACT: BACKGROUND:1,5-Anhydroglucitol (1,5-AG) is inversely related to hyperglycemia and may be a useful indicator of short-term (1-2 weeks) hyperglycemia and glycemic excursions, but its prognostic value is unclear. We sought to evaluate the associations of 1,5-AG with risk of diabetes and microvascular disease. METHODS:We measured 1,5-AG in blood samples from over 10 000 participants in the ARIC (Atherosclerosis Risk in Communities) Study (baseline, 1990-1992) and characterized the independent associations with prevalent retinopathy and with incident chronic kidney disease and incident diabetes during approximately 20 years of follow-up. RESULTS:We found that 1,5-AG was associated with prevalent retinopathy, driven primarily by the strong association in persons with diagnosed diabetes: adjusted odds ratio (OR) 11.26 (95% CI, 6.17-20.53) for <6 ?g/mL compared to 1,5-AG ?10 ?g/mL. This result remained significant after further adjustment for hemoglobin A(1c) (Hb A(1c)) (OR, 4.85; 95% CI, 2.42-9.74). In persons with diagnosed diabetes, low 1,5-AG (<6 ?g/mL vs ?10 ?g/mL) was also associated with a >2-fold increased risk of incident chronic kidney disease [adjusted hazard ratio (HR), 2.83; 95% CI, 2.15-3.74] and remained significant after adjustment for Hb A(1c) (HR, 1.43; 95% CI, 1.02-2.00). Nondiabetic participants with high 1,5-AG (?10 ?g/mL) had the lowest prevalence of retinopathy and lowest risk of kidney disease. In persons without diagnosed diabetes at baseline, 1,5-AG <10 ?g/mL was also associated with incident diabetes (adjusted HR, 2.29; 95% CI, 2.03-2.58). CONCLUSIONS:1,5-AG was associated with long-term risk of important microvascular outcomes, particularly in persons with diagnosed diabetes and even after adjustment for Hb A(1c). Our results suggest 1,5-AG may capture risk information associated with hyperglycemic excursions.