This study aims to investigate the relationship between the circulating level of homocysteine and body adiposity in Japanese patients with type 2 diabetes mellitus. We measured the body mass index (BMI), waist and hip circumferences, visceral and subcutaneous adiposities, visceral/subcutaneous (V/S) adiposity ratio, and insulin resistance as assessed by the Homeostasis Model Assessment (HOMA) index in patients with hyperhomocysteinemia. The study group consisted of 17 Japanese patients with type 2 diabetes and hyperhomocysteinemia (age: 62+/-10 years, mean+/-S.D.), and the control group consisted of 24 age-matched type 2 diabetes patients with normohomocysteinemia (60+/-11 years). The visceral adiposity, HOMA index, and V/S ratio were significantly higher in the hyperhomocysteinemia group than in the normohomocysteinemia group (P<0.05). In contrast, the BMI, hip circumference, and subcutaneous adiposity were similar between the two groups (P>0.1). Furthermore, multiple regression analysis showed that hyperhomocysteinemia was closely related to insulin resistance and visceral adiposity. Our results indicate that the presence of hyperhomocysteinemia in our population of Japanese patients with type 2 diabetes-associated insulin resistance was associated with increased visceral but not subcutaneous adiposity.