Objective To explore the diagnostic value of serum C-C motif chemokine ligand 3(CCL3)and Semaphorin 3A in patients with type 2 diabetes mellitus(T2DM)complicated by osteoporosis(OP).Methods A total of 125 patients with T2DM complicated by OP who visited the hospital from August 2022 to August 2023 were selected as the OP group,and another 125 patients with T2DM without OP who visited the hospital during the same period were selected as the T2DM group.The OP group was divided into Group A(T value>-1.0,but slightly lower than the normal value),Group B(T value between-2.5 and-1.0),and Group C(T value<-2.5)based on the measurement results of bone mineral density(BMD).The lev-els of serum CCL3 and Semaphorin 3A in each group were compared.Pearson correlation analysis was used to analyze the correlations between serum CCL3,Semaphorin 3A and BMD in patients with T2DM complicated by OP.Multivariate Logistic regression analysis was used to analyze the influencing factors of T2DM compli-cated by OP.The receiver operating characteristic(ROC)curve was used to analyze the diagnostic value of se-rum CCL3 and Semaphorin 3A for T2DM complicated by OP.Results Compared with the T2DM group,the serum CCL3 level in the OP group increased,and the Semaphorin 3A level decreased,and the difference was statistically significant(P<0.05).Compared with group A,the serum CCL3 levels in group B and group C increased,while the Semaphorin 3A level decreased,and the differences were statistically significant(P<0.05).Compared with group B,the serum CCL3 level in group C increased and the Semaphorin 3A level de-creased,and the difference was statistically significant(P<0.05).Compared with the T2DM group,the femo-ral neck bone BMD,lumbar spine BMD and total hip BMD in the OP group were significantly decreased,and the difference was statistically significant(P<0.05).The serum CCL3 level in patients with T2DM accompa-nied by OP was negatively correlated with femoral neck bone BMD,lumbar spine BMD and total hip BMD(P<0.05),and the serum Semaphorin 3A level was positively correlated with femoral neck bone BMD,lum-bar spine BMD and total hip BMD(P<0.05).The results of multivariate Logistic regression analysis showed that CCL3 was an independent risk factor for T2DM with OP(P<0.05),and Semaphorin 3A was an inde-pendent protective factor for T2DM with OP(P<0.05).The results of ROC curve analysis showed that the area under the curve(AUC)of serum CCL3,Semaphorin 3A and their combination diagnosis of T2DM accom-panied by OP were 0.810,0.802 and 0.869,respectively.The AUC of the combined diagnosis of T2DM ac-companied by OP was superior to their individual diagnoses(Zcombination-CCL3=2.235,Zcombination-Semaphorin 3A=2.021,P=0.025,0.043).Conclusion The serum CCL3 level is increased in patients with T2DM accompanied by OP,and the Semaphorin 3A level is decreased.The combination of the two has certain diagnostic value for T2DM accompanied by OP.