Objective: To test the feasibility of using 1,5-anhydroglucose alcohol (1,5-AG) as a diagnostic indicator of fulminant type 1 diabetes (FT1DM)., Methods: Fifteen patients with newly diagnosed FT1DM and 52 with type 2 diabetes (T2DM) were examined for serum biochemistry, glycosylated hemoglobin (HbAlc), and serum 1, 5-AG level., Results: The patients with FT1DM and T2DM showed significantly different fasting levels of blood glucose (FBG), fructosamine (FMN), creatinine (Cr), urea, HbAlc and serum 1,5-AG (P<0.05). In FT1DM patients, serum 1,5-AG was found to inversely correlate with FBG (r=-0.646, P=0.032) and FMN (r=-0.680, P=0.021), and in T2DM patients, serum 1,5-AG was inversely correlated with FBG (r=-0.407, P=0.001), FMN (r=-0.314, P=0.01) and HbAlc (r=-0.576, P<0.01). Receiver-operating characteristic (ROC) curve analysis showed an area under the curve of serum 1,5-AG of 0.804 with a cutoff value of 67.95, a sensitivity of 82.9% and a specificity of 60% for FT1DM diagnosis., Conclusion: Serum 1, 5-AG can reflect acute blood glucose fluctuation in FT1DM patients and is useful for differential diagnosis of FT1DM when combined with evaluations of the clinical characteristics of the patients and other related indicators.