The purpose of this study is to investigate tile effects of the Paecilomyces japonica on blood glucose in non-insulin dependent diabetes mellitus volunteers. During the 3 months of the experimental period, freeze-dried powder of Paecilomyces japonica (2 g/meal) was given to the subjects right before each meal. Paecilomyces japonica caused a significant decrease of $27.5\%;and;35.5\%$ in fasting and postprandial blood glucose levels, respectively. There were significant reductions of $28.5\%;and;33.5\%$ in fasting and postprandial blood glucose levels of the male subjects, respectively Paecilomyces japonica also significantly decreased in fasting and postprandial blood glucose levels of $26.1\%;and;37.3\%$ in female patients after treatment. This study shows that Paecilomyces japonica supplementation significantly lowered the fasting and postprandial glucose levels in NIDDM patients. These effects presumably contribute to the hypoglycemic activity.