Background: Emerging evidence suggests that genetic variations in taste receptor genes may influence dietary behaviors, energy homeostasis, and metabolic risk, contributing to type 2 diabetes mellitus (T2DM) pathogenesis. The objective of this study is to evaluate the association between single nucleotide polymorphisms (SNPs) in taste receptor genes and T2DM. Methods: This systematic review followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 guidelines and was registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022351880). A comprehensive literature search was conducted across PubMed, ScienceDirect, Cochrane Library, and Google Scholar through June 2025. Original studies examining SNPs in taste receptor genes among individuals with T2DM were included. Quality assessment was performed independently by using the Newcastle-Ottawa scale. Results: Sixteen studies involving diverse populations met the inclusion criteria. Significant associations with T2DM were observed for SNPs in type 2 taste receptor gene family R member 3 (TAS2R3; rs11763979), TAS2R4 (rs2233998), TAS2R7, TAS2R9, TAS2R38, TAS2R50, cluster determinant 36 (CD36; rs1761667, rs3211956, rs7755), carbonic anhydrase VI gene (CA6; rs2274327), transient receptor potential vanilloid-1 (TRPV1; rs161364, rs8065080), transient receptor potential cation channel subfamily M gene member 5 (TRPM5; rs4929982), and TRPM8 (rs12472151). These polymorphisms may alter taste perception and gut hormone responses [e.g., glucagon-like peptide 1 (GLP-1)], affecting dietary intake, satiety, insulin secretion, and glucose regulation. Discussion: The findings suggest that genetic variations in taste receptor genes may contribute to T2DM through behavioral and metabolic mechanisms. Incorporating gustatory phenotyping with genotypic profiling could enable personalized dietary strategies and inform novel therapeutic approaches targeting taste-mediated gut signaling. Further large-scale, multi-ethnic, and mechanistic studies are warranted to confirm these associations and elucidate their clinical implications.

Background: Diabetes mellitus and vitamin D deficiency (VDD) are widespread global health concerns with overlapping metabolic risks. Emerging evidence suggests a bidirectional relationship: VDD exacerbates insulin resistance, whereas diabetes mellitus disrupts vitamin D metabolism. Methods: This meta-analysis was registered prospectively (PROSPERO CRD42025639951). We conducted a comprehensive search of PubMed, Embase, Web of Science, and the Cochrane Library from their inception to January 2025 for observational studies examining the bidirectional associations between VDD and diabetes mellitus. Studies were eligible if they (1) employed cohort or case-control designs, (2) defined VDD as serum 25-hydroxyvitamin D [25(OH)D] < 20 ng/mL, and (3) diagnosed diabetes mellitus according to the American Diabetes Association (ADA) criteria. Two reviewers independently extracted data and assessed study quality using the Newcastle-Ottawa scale. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using random-effects models (STATA 15.1 and RevMan 5.4). Results: Among 53 studies (n = 552,032), individuals with VDD had a 53% increased risk of developing type 2 diabetes mellitus (T2DM) (OR = 1.53, 95% CI: 1.38–1.70). Conversely, individuals with type 1 diabetes mellitus (T1DM) and T2DM had a 2.02-fold and 2.62-fold increased risk of VDD, respectively. Subgroup analyses demonstrated stronger associations in Asian populations (T1DM: OR = 2.21; Europe: OR = 1.65; P < 0.05 for regional difference) and among normal-weight T2DM patients (OR = 7.68, compared to obese: OR = 5.21). Discussion: This meta-analysis reveals a bidirectional link between VDD and diabetes mellitus, emphasizing subtype- and phenotype-specific risk profiles. Clinically, routine monitoring of serum 25(OH)D levels is recommended for diabetic patients, particularly in high-risk subgroups such as individuals with T1DM or lean T2DM phenotypes, and suggests targeted vitamin D supplementation for high-risk groups. On a public health scale, fortifying staple foods with vitamin D in regions with high deficiency rates, such as Asia, could alleviate the dual burden of VDD and diabetes mellitus.

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency leads to high morbidity and mortality, despite the availability of life-saving corticosteroid replacement therapy. Gene therapy represents a promising potential treatment for monogenic disorders such as congenital adrenal hyperplasia, overcoming the limitations of corticosteroid replacement approaches. Adeno-associated viral vectors are currently the leading vector for direct in vivo gene delivery. However, physiological properties of the adrenal gland limit the application of adeno-associated viral vector-based gene addition strategies. To achieve durable correction in the adrenal gland, gene editing must be employed to stably introduce a genetic modification into the CYP21A2 locus. The safety of this and other gene editing approaches could be greatly improved by using lipid nanoparticles for the delivery of editing machinery mRNA. While little data exists regarding adrenocortical lipid nanoparticle targeting, physiological features of this organ (such as high relative blood flow, fenestrated endothelium, and cholesterol uptake) indicate the promise of these delivery vectors for the treatment of monogenic diseases of the adrenal cortex. This review discusses the complexities of developing gene therapy for congenital adrenal hyperplasia and explores the viability of novel gene therapy strategies in this application.