Abstract
BACKGROUND: Post-transplant diabetes mellitus (PTDM) affects up to 34% of heart transplant recipients (HTR) within five years, increasing the risk of adverse outcomes. Although the oral glucose tolerance test (OGTT) is the most sensitive method for detecting prediabetes and diabetes, it is burdensome. This study evaluates the diagnostic accuracy of exhaled breath analysis using an electronic nose (eNose) as a non-invasive alternative for detecting prediabetes or PTDM. METHODS: HTR > one year post-transplant undergoing OGTT were included, along with fasting HTR with known PTDM as a control group. Exhaled breath was analyzed before glucose loading using the SpiroNose. Diagnostic performance of eNose parameters alone and combined with clinical variables was assessed using multivariate logistic regression. RESULTS: Seventy-six HTR were included (29% female, median age 56 years, median 7.8 years post-transplant). Of these, 18 had normal glucose tolerance, 33 had prediabetes, and 25 had PTDM (including 8 newly diagnosed). Overall, 76% had prediabetes or PTDM. eNose alone differentiated normal from abnormal glucose tolerance (prediabetes or PTDM) with an AUROC of 0.70 (95% CI 0.57-0.83), 68% accuracy, 69% sensitivity, 67% specificity, 40% negative predictive value (NPV), and 87% positive predictive value (PPV). Combining eNose with clinical parameters improved diagnostic performance (AUROC 0.88, 95% CI 0.81-0.96), achieving 78% accuracy, 71% sensitivity, 100% specificity, 51% NPV, and 100% PPV. CONCLUSIONS: Prediabetes or PTDM is common in HTR. eNose technology, especially when combined with clinical data, shows promise as a non-invasive screening tool with high specificity and PPV. This approach may reduce OGTT burden, pending further confirmation.