A randomized, double-blind, placebo-controlled trial was carried out to investigate the effects of micronutrients supplementation on immunity and the incidence of common infections in type 2 diabetic outpatients. A total of 196 type 2 diabetic outpatients were randomized to receive tablets of micronutrients (n=97) or placebo (n=99) for 6 months. Individualized dietary energy intake and daily physical activity were recommended. Anthropometric measurements, blood biochemical variables and the incidence of common infections were measured at baseline and at 6 months. Data on diet, exercise and infection (upper respiratory tract infection, skin infection, urinary and genital tract infections, other infections) were recorded 1 month before the study and every month during the study. Blood concentrations of total protein, iron (Fe), folic acid and hemoglobin increased and unsaturated iron-binding capacity(UIBC) levels were decreased in the micronutrients supplementation group compared to the placebo group at 6 months. Moreover, at 6 months, compared to the placebo group, the blood concentrations of IgE, CD4+, CD4+/CD8+, WBC, lymphocyte counts, basophilic leukocyte increased and CD8+ count decreased in the supplementation group, and the levels of IgA, IgM, IgG and complements C3 and C4 did not differ. The incidence of upper respiratory infection, whitlow, dermapostasis, vaginitis, urinary tract infection, gingivitis and dental ulcer were lower and body temperature and duration of fever greatly improved in the supplementation than the placebo group. These data indicated that supplementation of micronutrients might increase immune function and reduce the incidence of common infections in type 2 diabetic outpatients.