Association of type 2 diabetes, obesity, and metabolic syndrome with patient-reported response to aeroallergen subcutaneous immunotherapy: A real-world cross-sectional study

Background: Although recent studies have examined the impact of metabolic diseases on the immune system, limited data exist on how these conditions and their treatments affect therapeutic approaches for atopic diseases, including subcutaneous immunotherapy (SCIT). Objective: The objective was to evaluate the association of type 2 diabetes mellitus (T2DM), obesity, metabolic syndrome, and patient-reported clinical response to SCIT in a real-world setting. Methods: We conducted an observational cross-sectional study of adults receiving SCIT at Montefiore Medical Center, Bronx, New York, between July and September 2024. The SCIT response was assessed by using visual analog scale scores for overall allergic rhinitis (AR) symptoms, nasal congestion, rhinorrhea, and ocular symptoms, stratified by T2DM, obesity (body mass index ≥ 30 kg/m ² ), and metabolic syndrome. Results: Overall, 95 patients were included, with a mean ± standard deviation age of 51 ± 16 years, the majority being women (71%). Twenty-five patients (26%) had T2DM, 53 (56%) were obese, and 27 (28%) had metabolic syndrome. In the entire cohort, 67% had improvement in overall AR symptoms with SCIT, 72% in nasal congestion, 67% in rhinorrhea, and 63% in ocular symptoms. T2DM was associated with significantly reduced odds of overall symptom improvement (odds ratio [OR] 0.23 [95% confidence interval {CI}, 0.06‐0.89]; p = 0.037). The patients with metabolic syndrome had significantly lower odds of improvement in overall AR symptoms (OR 0.21 [95% CI, 0.03‐0.61]; p = 0.010), nasal congestion (OR 0.24 [95% CI, 0.06‐0.88]; p = 0.036), and rhinorrhea (OR 0.22 [95% CI, 0.06‐ 0.75]; p = 0.019) while on SCIT. Use of metformin, insulin, sulfonylureas, or glucagon-like peptide-1 receptor agonists did not significantly influence the SCIT response. Conclusion: T2DM and metabolic syndrome may identify a subgroup of patients with lower improvement after SCIT. Prospective studies are needed to determine whether metabolic disorders predict SCIT-associated responsiveness.