Abstract: OBJECTIVE To explore the value of plasma procalcitonin (PCT) in predicting the infection of patients with diabetic ketoacidosis (DKA). METHODS A total of 115 cases of diabetic ketoacidosis were selected from Mar. 2011 to Jun. 2016 in the hospital, and were divided into 25 cases of diabetic ketoacidosis severe infection group (heavy infection group), 30 cases of local infection (light infection group), and 60 cases without infection (non-infected group) according to whether the infection occurred and the degree, and another 60 cases of diabetes patients without ketoacidosis were selected as control group. The plasma procalcitonin concentrations (PCT) of the four groups of patients on admission, at the second day and the third day were measured, procalcitonin decline concentrations of the three groups with ketoacidosis of the first and the second day in plasma were measured, and the cases with different plasma concentrations of PCT of the 3 groups of patients were analyze. RESULTS On admission, the plasma procalcitonin concentrations were 0.22±0.12 ng/ml in control group, 1.29±1.27 ng/ml in heavy infection group, 1.18±1.19 ng/ml in light infection group and 0.82±0.90 ng/mL in non-infected group. At the second day, the plasma PCT concentrations were 0.17±0.11 ng/ml in control group, 1.13±1.07 ng/ml in heavy infection group, 1.05±1.09 ng/ml in light infection group, and 0.65±0.62 ng/ml in non-infected group. At the third day, the plasma PCT concentrations were 0.12±0.07 ng/ml in control group, 0.93±0.89 ng/ml in heavy group, 0.85±0.92 ng/ml in light infection group and 0.35±0.92ng in non-infected group. There were significant differences in the plasma PCT concentration among heavy infection group, light infection group and non-infected group (P<0.05). The patients with plasma calcitonin in the concentration of 0.5-2 ng/ml of the three groups were all more than 30.00%, and with plasma calcitonin concentration> 2 ng/ml were only in heavy infection group which were more than 50.00%. CONCLUSION Plasma procalcitonin concentration in early diabetic ketoacidosis patients can play a certain role in the prediction of infection. The decline of plasma PCT concentration at the second day can play a better predictive effect in the prediction of infection in patients with diabetic ketoacidosis.