Early diagnosis of hospitalized elderly patients with infectious stress hyperglycaemia (ISH) is clinically important, as without timely prevention and effective treatment, it is likely to deteriorate into septic shock, which significantly worsen patients’ survival rate. Systematic screening of specific biomarkers of serum small extracellular vesicles (sEVs) from ISH patient has not yet been reported. In this study, serum sEVs were derived from 10 elderly patients with ISH and 5 control patients with disease-match without hyperlycemia (non-ISH). RNA sequencing identified a total number of 49 sEVs enriched fraction derived miRNAs with differential expression between ISH and control group. Of which, top 22 miRNAs ranked by sensitivity × specificity were chosen for further research. Moreover,7 out of 22 miRNAs that related to glucose metabolism or immune disorder, were picked up for further validation in an independent cohort consisting of 52 participants (31 ISH and 21 non-ISH). A validation analysis revealed that 3 miRNAs (hsa-miR-21-5p，hsa-miR-335-5p，hsa-miR-28-3p) were statistically up-regulated in exosomes from ISH patients. In the validation cohort and discovery cohort, the AUC of 3 individual miRNAs ranged from 0.73 to 0.88. A logistic model combining three miRNAs achieved an AUC of 0.96. Besides,sEV‐miRNA‐based signatures effectively characterized patients’ poor clinical outcome. Survival curve analysis showed that miR-335-5p, miR-28-3p but not miR-21-5p, were significantly closely related to mortality, and the combination of the three could also predict patients outcome.(P<0.05).This study depicted the circulating exosomal miRNAs change in ISH patient and which could be used as a promising biomarker to detect ISH at an early stage, and predict patients clinical outcome.