Intensive insulin therapy composed of bolus and basal insulin has been believed as the most powerful recipe for glycemic control of both type 1 and type 2 diabetes. In this study, we investigated the effects of changes in basal/total daily insulin ratio (B/TD ratio) in type 2 diabetes patients on intensive insulin therapy including insulin glargine. The B/TD ratio used in our Japanese patients was about 0.35, and the ratio was increased up to about 0.46+/-0.12 without change of total insulin daily dose. After 24-week-treatment, mean glycated albumin of the patients whose B/TD ratio was increased was significantly lower than those of the patients whose B/TD ratio was not changed. Our results suggest that adequate supplementation of basal insulin may be important for maximum effect of bolus insulin even in Japanese who have serious defect in postprandial rapid insulin secretion.