Abstract： Objective To explore the clinical characteristics of type 2 diabetic patients with carboxypeptidase H antibody (CPH Ab) and to disclose the value of CPH Ab in the diagnosis of latent autoimmune diabetes in adults (LADA). Methods We screened 545 patients with initially diagnosed type 2 diabetes mellitus (T2DM), 85 type 1 diabetic (T1DM) patients and 123 healthy controls for CPH Ab assay, and also GAD Ab assay for the T2DM group. T2DM patients were divided into 3 groups according to CPH Ab and GAD Ab to compare the clinical characteristics of them. CPH Ab and GAD Ab were detected with RIA. Results The prevalence of CPH Ab in T2DM (5.5% ,30/545) was higher than that of T1DM patients(0%,0/85; P <0.05) and healthy controls (0.8%, 1/123; P< 0.05). Only 1 was GAD Ab positive in 30 type 2 diabetics with positive CPH Ab. The positivity of CPH Ab was more higher in patients with lower body weight (BMI<21 kg/m 2), and the patients with CPH Ab had a wider range of age at onset, longer duration of disease, lower body mass index and more tendency to develop ketosis. Their fasting C peptide level was between those of the patients with GAD Ab and the patients without any antibody (GAD Ab and CPH Ab), and these patients had less metabolic syndrome (including lower levels of BMI, hypertension percentage and serum triglyceride) and more peripheral neuropathy. Conclusion The clinical characteristics of patients with CPH Ab are between that of classical LADA who is GAD Ab positive and T2DM patients. CPH Ab was a new autoimmune marker for the diagnosis of LADA