Relationships between diabetes, vitamin D status, depression, and Hispanic ethnicity: a project FRONTIER study

Nutrition & Diabetes ARTICLE www.nature.com/nutd OPEN Relationships between diabetes, vitamin D status, depression, and Hispanic ethnicity: a project FRONTIER study Riley McCready1,2,3, Claudia Morris1,2,3, Philip Antwi-Adjei1, Mohammed Pourghaed1,2,3, Ashish Sarangi4, Annette Boles3, Felipe Ramirez-Velandia3, Jonathan Kopel2,5,12, John Culberson 2,6, Jonathan Singer1,2,3,4,7,8, Gabriela Ashworth1,3,8, ✉ Marwan N. Sabbagh9, Volker Neugebauer1,2,3,8,10, Boris Decourt1,2,3,8, Andrew C. Shin 8,10,11 and J. Josh Lawrence 1,2,3,8,10 © The Author(s) 2026 1234567890();,: BACKGROUND/OBJECTIVES: Vitamin D (VD) status has been linked to the development of diabetes. However, this relationship in the context of comorbid conditions remains understudied. Additionally, ethnic disparities in nutritional status and chronic disease prevalence within rural populations are a vastly underrepresented area of research. In our previous study, we explored VD levels and depression in a rural West Texas aging sample. In the present study, we investigated the associations between diabetes, vitamin D (VD) levels, depression, and Hispanic ethnicity (HE) among a sample of aging, rural West Texans from Project FRONTIER (PF; Facing Rural Obstacles to Health Care Now Through Intervention, Education, and Research). SUBJECTS/METHODS: A cohort of 299 PF participants (mean age 62.6 ± 11.8 years old, 70.9% female, 40.5% HE) was used. We examined relationships between diabetes diagnosis, blood-based diabetes-related biomarkers, VD level, Geriatric Depression Scale (GDS) score, and HE status. We developed a “VD-sensitive GDS score” composed of the 9 GDS questions that were significantly correlated with VD level in our previous study. We further created a complementary “VD-insensitive GDS score” composed of the remaining 21 GDS questions. Standard correlation and regression analyses were employed. RESULTS: VD level was significantly negatively associated with diabetes diagnosis, while VD-sensitive depression score was significantly positively associated with diabetes diagnosis. HE was associated with higher HbA1c levels, higher fasting blood glucose levels, and higher VD-sensitive depression scores. CONCLUSIONS: In this rural West Texas cohort, diabetes was significantly associated with low VD levels and high VD-sensitive depression scores. HE was associated with higher levels of diabetes-related biomarkers and higher VD-sensitive depression scores. These disparities are crucial to consider when examining areas for healthcare improvement in West Texas, particularly among aging populations. Nutrition and Diabetes (2026)16:1 ; https://doi.org/10.1038/s41387-025-00409-3 INTRODUCTION Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia. The majority of cases (90–95%) involve a dysregulated response to insulin and are classified as type 2 DM [1]. Higher rates of diabetes have been reported in Hispanic populations due to factors including lower socioeconomic status, a cultural diet high in carbohydrates and saturated fat, and genetic susceptibility to insulin resistance [2, 3]. Diabetes has been linked to a variety of comorbid conditions, including depression, which is of particular concern in the aging population [4]. When considering factors contributing to the development of diabetes, many identify nutritional deficiencies as a potential link; studies have found significant associations between low vitamin D (VD) levels and diabetes [5, 6]. VD level has also been linked with comorbid conditions that frequently occur alongside diabetes; a substantial connection between low VD levels and depression has been established [7]. Just as diabetes is a worldwide health issue, vitamin D deficiency (VDD) and vitamin D insufficiency (VDI) impact diverse populations around the globe [8]. According to the Endocrine Society, VDD is defined as a 25(OH)D level of 20 ng/mL or lower, and VDI as a 25(OH)D of 21–29 ng/mL [9]. There is a particularly high prevalence of VDD/VDI amongst Hispanic populations due to factors including darker skin pigmentation, higher rates of obesity, and poorer overall health status [10]. Moreover, there is an agedependent reduction in the body’s ability to synthesize and absorb VD [11]. Thus, it is essential to consider how nutritional status impacts the development of chronic conditions in older 1 Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 2School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 3Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 4Department of Psychiatry, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 5MD/PhD Program, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 6Department of Family Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 7Department of Psychological Sciences, Texas Tech University, Lubbock, TX, USA. 8Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 9Department of Neurology, Barrow Neurological Institute, Phoenix, AZ, USA. 10Center of Excellence for Integrated Health, Texas Tech University Health Sciences Center, Lubbock, TX, USA. 11Neurobiology of Nutrition Laboratory, Department of Nutritional Sciences, Texas Tech University, Lubbock, TX, USA. 12Present address: MedStar Georgetown, Georgetown University, Washington, DC, USA. ✉email: Received: 23 November 2024 Revised: 26 September 2025 Accepted: 26 November 2025 R. McCready et al. 2 individuals within rural communities with large Hispanic populations, such as West Texas. In a previous study, we examined VD level and depression in a rural West Texas aging sample from the TTUHSC-managed epidemiological study termed Project FRONTIER (PF; Facing Rural Obstacles to Health Care Now Through Intervention, Education, and Research) [12, 13]. Significant negative associations were identified between VD levels and Geriatric Depression Scale (GDS) scores, and Hispanic participants had significantly lower VD levels [12]. Other studies using PF data have explored the relationships between ethnic disparities and depression in older adults [14]. However, there remains a critical knowledge gap about the possibility that VD levels could serve as a proxy marker of diabetes and comorbid conditions in older adults. Previous research has linked VDD/VDI to increased risk of development of DM [15], yet few studies have focused on identifying these disparities in an older West Texas population with a large Hispanic demographic. Therefore, more research is necessary to elucidate relationships between these disease processes. To better identify opportunities for intervention, education, and research, this study explored the relationships between diabetes, VD level, depression, and Hispanic ethnicity (HE) in an aging West Texas cohort. A su (...truncated)