Abstract: Objective To explore the correlation between serum circulating long non-coding RNA human leukocyte antigen complex 18(LncRNA HCG18),microRNA-185-5p(miR-185-5p) levels and vascular calcification in patients with diabetic kidney disease(DKD).Methods From October 2018 to September 2021,145 DKD patients were recruited.According to the status of vascular calcification,they were divided into two groups of calcification(n=70) and non-calcification(n=75).And another 70 cases of normal physical examination during the same period were selected as control group.Fluorescent quantitative polymerase chain reaction(PCR) was utilized for detecting serum levels of LncRNA HCG18 and miR-185-5p;automatic biochemical analyzer was utilized for measuring the blood parameters of calcium(Ca²⁺),phosphorus(P³⁺) and creatinine(Scr);a microplate reader for measuring the levels of alkaline phosphatase(ALP),high-sensitivity C-reactive protein(hs-CRP) and parathyroid hormone(PTH);Pearson’s method for examining the correlation between serum LncRNA HCG18,miR-185-5p and vascular calcification-related parameters;receiver operating characteristic(ROC) curve plotted for examining the diagnostic value of serum LncRNA HCG18 and miR-185-5p levels for DKD with vascular calcification.Results Serum LncRNA HCG18,Ca²⁺,P³⁺,Scr,ALP,hs-CRP and PTH were higher in calcification and non-calcification groups than those in control group(P＜0.05) and serum miR-185-5p level was lower than that in control group(P＜0.05);serum LncRNA HCG18,Ca²⁺,P³⁺,Scr,ALP,hs-CRP and PTH were higher in calcification group than those in non-calcification group(P＜0.05) while serum miR-185-5p level was lower than that in non-calcification group(P＜0.05).Serum LncRNA HCG18 in DKD patients plus vascular calcification was negatively correlated with miR-185-5p(P＜0.05),serum LncRNA HCG18 was positively correlated with Ca²⁺,P³⁺,Scr,ALP,hs-CRP and PTH(P＜0.05),and miR-185-5p was negatively correlated with Ca²⁺,P³⁺,Scr,ALP,hs-CRP and PTH(P＜0.05).The area under the curve of serum levels of LncRNA HCG18,miR-185-5p and the combination in the diagnosis of DKD with vascular calcification was 0.820,0.758 and 0.880 respectively.Conclusion Serum LncRNA HCG18 is highly expressed while miR-185-5p is lowly expressed in sera of DKD patients with vascular calcification.Both have some diagnostic value for vascular calcification in DKD patients and co-detection has a higher diagnostic value.