Beyond glucose: wearable and implantable biosensors for continuous monitoring of metabolic, hormonal, and inflammatory biomarkers in personalized cardiometabolic care.

Wearable and implantable biosensors are shifting biochemical assessment from episodic laboratory testing to continuous, context-rich physiological monitoring. Glucose remains the most successful translational model because continuous glucose monitoring has already established a credible pathway for analytical validation, clinical adoption, reimbursement, and regulatory approval. Yet cardiometabolic disease is not a single-analyte disorder. Insulin resistance, obesity, hypertension, heart failure, chronic kidney disease, stress-axis dysregulation, and chronic low-grade inflammation arise from interacting metabolic, endocrine, neural, and immune pathways. The next phase of the field therefore depends on whether biosensors can move beyond glucose while remaining biologically interpretable and clinically actionable. In this narrative review, we argue that personalized cardiometabolic care is the most attractive entry point for next-generation wearable and implantable biosensors because it combines high disease burden, dynamic physiology, rich biomarker biology, and an already established translational archetype. We integrate two complementary perspectives: a biomarker-centered framework that prioritizes glucose, lactate, ketones, uric acid, electrolytes, renal metabolites, cortisol, catecholamines, cytokines, acute-phase proteins, and selected cardiac markers; and a device-centered framework that examines sweat patches, microneedle-enabled interstitial fluid sensors, implantable systems, smart textiles, oral and ocular platforms, and hybrid closed-loop architectures. Particular emphasis is placed on biomarker-biofluid-device matching, the distinction between laboratory equivalence and continuous phenotyping, and the engineering barriers that determine real-world success, including partitioning across biofluids, skin-device coupling, biofouling, foreign-body response, calibration drift, reversibility of affinity-based sensing, power management, and multimodal data interpretation. We further discuss materials and interface strategies such as laser-induced graphene, conductive polymers, carbon nanomaterials, metal-organic frameworks, anti-fouling hydrogels, zwitterionic coatings, and drug-eluting surfaces; disease applications spanning diabetes, metabolic syndrome, heart failure, cardio-renal disease, and diabetic wound care; and the analytical, regulatory, and human-factor requirements for clinical adoption. The central message is that beyond-glucose biosensing will succeed only if it remains glucose-informed: glucose should serve as the translational backbone onto which additional metabolic, hormonal, inflammatory, and cardiovascular signals are layered according to biological kinetics, matrix suitability, and clinical decision need.