Aim The purpose of this study was to investigate the relationship between carotid intima-media thickness (C-IMT) and glutamate decarboxylase antibody (GADA) titer in latent autoimmune diabetes in adults (LADA).Methods The data of 160 patients were selected from a randomized controlled clinical trial “Multi-center study of optimized LADA treatment based on protecting islet β-cell function” (NCT02407899) led by the National Clinical Research Center for Metabolic Diseases of the Second Xiangya Hospital of Central South University from September 2015 to April 2019. GADA titer was used as the cut-off value to divide LADA patients into LADA-1 (GADA≥0.3) with high titer and LADA-2 (0.05≤GADA<0.3) with low titer. C-IMT data and other clinical data were also collected for the cross-sectional study. Results Patients with type LADA-2 had significantly higher age, hypertension ratio, metabolic syndrome ratio, weight, body mass index, waist circumference, hip circumference, systolic blood pressure, diastolic blood pressure, fasting C-peptide, HOMA-IR and triglyceride levels(P＜0.05), but lower insulin usage ratio than patients with LADA-1(P＜0.01). Compared with patients with LADA-1, patients with LADA-2 had significantly higher percentage of thickened C-IMT (P＜0.01)and thicker C-IMT (P＜0.001). The difference is still significant after adjusting for related factors of metabolic syndrome. Multiple linear regression analysis showed that C-IMT was positively correlated with drinking history (P＜0.01) and negatively correlated with GADA titer (P＜0.01). The LADA patients were divided into low HOMA-IR (HOMA-IR≤2.0) and high HOMA-IR(HOMA-IR＞2.0) groups. LADA-1 patients with high HOMA-IR had significantly increased C-IMT than those with low HOMA-IR. (P＜0.01), but there was no difference between LADA-2 patients with low and high HOMA-IR. Conclusion LADA patients with low GADA titer have a higher risk of atherosclerosis than LADA patients with higher GADA titer, and the risk is associated with insulin resistance. GADA titer is an independent factor of C-IMT in LADA patients.