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. Anthropomet- ric measurements, blood biochemical variables and the incidence of common infections were measured at base- line and at 6 months. Data on diet, exercise and infection (upper respiratory tract infection, skin infection, uri- nary and genital tract infections, other infections) were recorded 1 month before the study and every month dur- ing the study. Blood concentrations of total protein, iron (Fe), folic acid and hemoglobin increased and unsatu- rated 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 concentra- tions of IgE, CD4+, CD4+/CD8+, WBC, lymphocyte counts, basophilic leukocyte increased and CD8+ count de- creased in the supplementation group, and the levels of IgA, IgM, IgG and complements C3 and C4 did not dif- fer. The incidence of upper respiratory infection, whitlow, dermapostasis, vaginitis, urinary tract infection, gin- givitis and dental ulcer were lower and body temperature and duration of fever greatly improved in the supple- mentation 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.