Plasma apelin: A novel biomarker for predicting diabetes

Background: Apelin regulates insulin sensitivity and secretion in animals. However, whether plasma apelin predicts incident diabetes in humans remains unknown. Methods: We studied a cohort including 447 subjects (148 men, 299 women) without diabetes and followed for an average of 3 y. Diabetes was diagnosed by an oral glucose tolerance test, plasma hemoglobin A1c, and if the subject was taking medications for diabetes. Plasma apelin-12 at baseline was measured with a commercial kit. Results: Plasma apelin concentrations were higher in women than in men at baseline (p = 0.007). During follow-up, 43 subjects developed type 2 diabetes. Higher plasma apelin concentrations were associated with a higher risk of diabetes in men (p = 0.049) but not in women. Plasma apelin predicted incident type 2 diabetes in men (hazard ratio, 2.13, 95% CI 1.29-3.51, p < 0.05), but not in women, adjusted for age, family history of diabetes, hemoglobin A1c, body mass index, hypertension, and HOMA2-IR. Apelin could improve the prediction ability beyond traditional risk factors in men, and the sensitivity and specificity of plasma apelin at 0.9 ng/ml for this prediction were 63.2% and 58.9%, respectively. In men at risk for diabetes (HbA1c 5.7-6.4%, FPG 100-125 mg/dl, or OGIT-2 h-PG 140-199 mg/dl), the risk for developing diabetes was higher in those with higher plasma apelin concentration than in those with lower plasma apelin concentrations (10.6%/year vs. 5.1%/year, p < 0.001). Conclusions: Plasma apelin is a novel biomarker for predicting type 2 diabetes in men. (C) 2014 Elsevier B.V. All rights reserved.