The contents of trace elements Fe, Cr, Co and Ni in serum of middle-aged and aged people with slight and severe diabetes were determined and compared with the control group. The results showed that the concentrations of Fe and Cr of the case groups were lower than those of the control group, and there was a significant difference between the two case groups (P < 0.01). The content of Ni was lowered during the initial stage of diabetes, and changed into normal gradually. There was significant difference between group of higher blood sugar and the control group (P < 0.05), and even more significant difference between the two case groups(P < 0.01). The content of Co rose with the patient's condition worsened, but there was no statistical significance (P < 0.05).