Objective To investigate the diagnostic value of color Doppler ultrasonography (CDU) combined with serum high-sensitivity C-reactive protein (hs-CRP) and Omentin-1 (OMentin-1) in the elderly patients with type 2 diabetes mellitus (T2DM) complicated with lower extremity vascular disease (LEVD). Methods A total of 250 elderly T2DM patients admitted to the Hai′an People′s Hospital from July 2020 to October 2022 were selected and divided into T2DM group (n=118) and T2DM-LEVD group (n=132) according to the occurrence of LEVD. Another 100 healthy elderly volunteers who underwent physical examination during the same period were selected as the normal group (NC group). General data of the subjects were collected, and CDU was performed to obtain the lower extremity hemodynamics, plaque formation rate and rate of dorsalis pedis artery stenosis. Serum hs-CRP and Omentin-1 levels were measured. The three groups were compared in the above indexes. Binary logistic regression model was used to analyze factors affecting T2DM-LEVD, and receiver operating characteristic (ROC) curve was drawn to analyze the diagnostic value of the CDU combined with serum hs-CRP and Omentin-1 detection for T2DM-LEVD. SPSS statistics 24.0 was used for statistical analysis. Data comparison between two groups was perfomed using t test, χ² test or analysis of variance depending on data type. Results There were no diffe-rences in gender, age, body mass index (BMI), history of smoking, history of drinking, and course of disease among the three groups (P>0.05). The levels of glycosylated hemoglobin (HbA1c), fasting blood glucose (FPG), total cholesterol (TC), triglyceride (TG), fasting insulin (FINS), insulin resistance (HOMA-IR) index, urea nitrogen (BUN), rate of plaque formation, rate of dorsalis pedis artery stenosis, and the serum hs-CRP in the T2DM-LEVD group were higher than those in the T2DM and NC groups, and those in the T2DM group were higher than those in the NC group. The high-density lipoprotein cholesterol (HDL-C) and albumin (ALB), internal diameter and blood flow of the femoral artery, popliteal artery and dorsal foot artery, and serum Omentin-1 level in the T2DM were lower than those in the T2DM and NC groups, and those in the T2DM group were lower than those in the NC groups, and the differences were statistically significant (P<0.05). Logistic analysis showed that HbA1c, FPG, and the internal diameter and blood flow of the femoral artery, popliteal artery and dorsal pedis artery, hs-CRP, and Omentin-1 were the factors affecting the occurrence of T2DM-LEVD (P<0.05). ROC curve showed that the area under the curve (AUC), sensitivity and specificity of the combined CDU, hs-CRP and Omentin-1 were higher than any of the three alone in the diagnosis of T2DM-LEVD (P<0.05). Conclusion CDU combined with serum hs-CRP and Omentin-1 levels is of high diagnostic value in the elderly patients with T2DM and LEVD.