Exosomal microRNAs (miRNAs/miRs) are potential biomarkers for the diagnosis and treatment of cardiovascular disease, and hyperglycemia serves an important role in the development of atherosclerosis. The present study aimed to investigate the expression profile of serum­derived exosomal miRNAs in coronary heart disease (CHD) with hyperglycemia, and to identify effective biomarkers for predicting coronary artery lesions. Serum samples were collected from eight patients with CHD and hyperglycemia and eight patients with CHD and normoglycemia, exosomes were isolated and differentially expressed miRNAs (DEMIs) were filtered using a human miRNA microarray. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed using standard enrichment computational methods for the target genes of DEMIs. Receiver operating characteristic (ROC) curve analysis was applied to evaluate the values of the selected DEMIs in predicting the severity of coronary stenosis. A total of 10 DEMIs, including four upregulated miRNAs (hsa­let­7b­5p, hsa­miR­4313, hsa­miR­4665­3p and hsa­miR­940) and six downregulated miRNAs (hsa­miR­4459, hsa­miR­4687­3p, hsa­miR­6087, hsa­miR­6089, hsa­miR­6740­5p and hsa­miR­6800­5p), were screened in patients with CHD and hyperglycemia. GO analysis showed that the 'cellular process', 'single­organism process' and 'biological regulation' were significantly enriched. KEGG pathway analysis revealed that the 'mTOR signaling pathway', 'FoxO signaling pathway' and 'neurotrophin signaling pathway' were significantly enriched. Among these DEMIs, only hsa­let­7b­5p expression was positively correlated with both hemoglobin A1C levels and Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery score. ROC curves showed that hsa­let­7b­5p could serve as an effective biomarker for differentiating the severity of coronary stenosis. In conclusion, the present study demonstrated that serum­derived exosomal hsa­let­7b­5p is upregulated in patients with CHD and hyperglycemia, and may serve as a noninvasive biomarker for the severity of coronary stenosis.