We first clarified the relationship between abdominal visceral fat accumulation and impaired glucose and lipid metabolism in patients with myotonic dystrophy. Nineteen patients aged 44.2 +/- 11.4 years with a body mass index (BMI) of 20.5 +/- 2.8 kg/m2, and 18 controls aged 45.2 +/- 10.3 years, with a BMI 20.0 +/- 2.8 kg/m2 were examined. The distribution of abdominal visceral and subcutaneous fat was examined by CT scanning at the umbilical level. Visceral fat area was significantly greater in myotonic dystrophy than that in control (p < 0.05), and positively correlated with the levels of fasting plasma glucose (r = 0.65 p < 0.01), plasma glucose area under the curve of 75 g oral glucose tolerance test (r = 0.67 p < 0.01), fasting plasma insulin (r = 0.77 p < 0.001), serum total cholesterol (r = 0.71 p < 0.001) and serum triglyceride (r = 0.68 p < 0.01). From the present results, we speculate that excess visceral fat accumulation in myotonic dystrophy induces impaired glucose and lipid metabolism.