5 g oral glucose tolerant test and insulin releasing test were performed in 33 patients with type Ⅱ diabetes mellitus.Glycosylated insulin(GI)was determinated with nitroblue tetrazolium(NBT)colorreaction using anti-insulin antibody for precipitation of serum insulin.GI level was increased significantly in diabetics and correlated positive with fasting blood glucose concentration, negative with the ratio of fasting serum insulin/glucose concentration and the ratio of the area under the insulin curve over the area under the glucose curve. The results indicate that GI level depends on the condition of the blood glucose control and is involved in the development of insulin resistance.