Nateglinide is a novel rapid- and short-acting insulin secretagogue that ameliorates postprandial hyperglycemia by improving insulin secretory dynamics to a near normal level more effectively than sulfonylureas. Recent epidemiological studies have demonstrated that postprandial hyperglycemia can result in arteriosclerosis, and that advanced arteriosclerosis is present in the initial stage of impaired glucose tolerance. Since postprandial hyperglycemia could be well treated by nateglinide, we examined the background factors of type 2 diabetic patients to determine the optimal indication for nateglinide. Our results indicate that nateglinide is most effective in young and obese patients. Furthermore, fewer responders had microangiopathy or were previously on oral hypoglycemic agents or sulfonylureas compared with non-responders. Although nateglinide is generally indicated for patients with mild HbA1c level, the present findings indicate that the drug was effective in the aforementioned patients regardless of pretreatment HbA1c levels. In one obese patient, nateglinide improved late hyperinsulinemia to near normal secretory dynamics. Our findings suggest that nateglinide is a physiologically preferable and useful drug for early type 2 diabetes without microangiopathy.