Potential Biomarkers for the Early Prediction of Prediabetes

Abstract

Background/Objective: Prediabetes is increasingly recognized as a state of chronic, low-grade inflammation that contributes to early β-cell dysfunction, insulin resistance, and progression to type 2 diabetes (T2D). This review synthesizes mechanistic and clinical evidence to characterize the inflammatory landscape of prediabetes, evaluate the consistency of candidate biomarkers, and assess potential for clinical translation. Methods: We conducted a structured narrative review and assessed 22 studies investigating inflammatory and metabolic biomarkers for prediabetes across experimental animal models, human pancreatic islets, and clinical cohorts. Biomarkers included cytokines, oxidative stress indicators, microRNAs, and immune-cell-associated factors. Studies included cross-sectional, longitudinal, and mechanistic designs. Results: Clinical studies generally reported higher CRP and hsCRP. In several cohorts, IL-6 and other inflammatory mediators were increased in individuals with prediabetes. However, inflammatory responses were not uniform across studies. One study reported elevated IL-10 and IL-4 in addition to hsCRP, while TNF-α and IL-6 were not significantly different. Overall, CRP and hsCRP demonstrated the strongest clinical translational evidence, with findings replicated across multiple cohorts and longitudinal evidence linking higher baseline hsCRP or CRP with increased risk of progression to T2D. Other candidates, including IL-6, TNF-α, adiponectin, SFRP4, oxidative stress markers, and microRNAs, remain promising but have more limited or inconsistent evidence for clinical application. Conclusions: Prediabetes is characterized by a multifaceted inflammatory response involving innate and adaptive immune pathways, altered cytokine and microRNA profiles, oxidative stress, and adipose–pancreatic interactions. Although inflammatory biomarkers may enhance conventional metabolic measures for risk stratification, current evidence does not establish any inflammatory marker as a standalone diagnostic test for prediabetes.