The Diabetes-Viral Respiratory Syndemic: Pathophysiological Insights and Precision Management: A Scoping Review

Background/Objectives: Viral respiratory tract infections (VRTIs) in patients with diabetes mellitus (DM) are characterized by a severity gap rather than an infection gap. This review synthesizes evidence from the 2023-2026 respiratory seasons to provide a post-pandemic framework for managing the synergistic metabolic and viral threats in this population. Materials and Methods: A scoping review of literature from PubMed, Scopus, and Embase (2023-2026) was conducted, focusing on clinical outcomes and mechanistic interactions between DM and emerging respiratory pathogens. Results: Recent data identify human Metapneumovirus (hMPV) and adenovirus as significant threats to diabetic hosts, with mortality risks equivalent to seasonal influenza (HR 1.00 for hMPV vs. influenza). The two-hit model combines a baseline of innate immune paralysis, characterized by impaired neutrophil chemo-taxis and mechanical SP-D dysfunction, with a cellular signaling environment primed for cytokine overreaction by epigenetic metabolic memory. The stress hyperglycemia ratio (SHR) has emerged as a promising predictor of mortality compared to absolute glucose or HbA1c, with a proposed threshold of ≥1.14 identifying patients at 3.5-fold increased risk for mechanical ventilation. Precision management should consider the prudent suspension of SGLT2 inhibitors to mitigate euglycemic DKA risks and considering the early use of GLP-1 receptor agonists for their hypothesized pulmonary anti-inflammatory properties. Conclusions: Closing the mortality gap may require a shift from generic viral care to a precision model that treats metabolic susceptibility with high clinical priority alongside the treatment of the viral pathogen.