Objective To investigate if edema caused by rosiglitazone is associated with the change of aldosterone level. Methods Plasma aldosterone levels in different periods from patients treated with rosiglitazone combined with insulin were measured.Type 2 diabetes patients who have been treated with insulin alone were divided into two groups: patients treated with rosiglitazone(4mg/d) combined with insulin(RSG+insulin group), or treated with insulin alone (insulin group)(n=10). Aldosterone levels, incidence of edema and weight gain were monitored every two months during six months. Results The incidence of edema and weight gain were higher in RSG+insulin group than in insulin group. After two months, aldosterone levels were higher in RSG+insulin group than in insulin group[(77.8±25.9)vs(60.2±27.6)pg/ml,P＞0.05],but it had no statistical difference; after four months, aldosterone levels were higher in RSG+insulin group than in insulin group[(87.2±27.1)vs (61.5±25.6) pg/ml,P＜0.05]. After six months, aldosterone level recovered gradually,it had no statistical difference compared with that of control[(77.0±21.0)vs(69.6±21.7) pg/ml,P＞0.05]. Conclusions The cause of early edema in type 2 diabetic patients treated with rosiglitazone combined with insulin was probably assosiated with elevated aldosterone level.