We measured serum 1,5 anhydroglucitol (1,5AG) levels by HPLC in 32 patients with liver cirrhosis, 32 with diabetes mellitus and 61 normal subjects. Serum 1,5AG was significantly lower in patients with diabetes mellitus and liver cirrhosis compared with that in normal subjects. Serum levels of type IV collagen were higher in patients with liver cirrhosis than in those without liver cirrhosis. A negative correlation was observed between serum 1,5AG and type IV collagen in patients with liver cirrhosis (r = -0.37, p < 0.05), but not in patients with diabetes mellitus. These data suggest that serum 1,5AG levels reflect the degree of liver cirrhosis.