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Bone and Mineral Metabolism

MON-836 - Vitamin D status in type 2 diabetes: adiposity outweighs sun exposure in a tropical Caribbean cohort — a pilot study

Monday, June 15, 2026
9:00 AM - 2:00 PM CT


Background: Vitamin D deficiency has been linked to insulin resistance and adverse outcomes in type 2 diabetes (T2D). Evidence comes mostly from temperate regions, and data from tropical Caribbean populations are scarce. Despite residing at ~19°N with year-round ultraviolet B (UVB) radiation, the burden and determinants of hypovitaminosis D in Dominican T2D patients remain unknown.

Objective: To estimate the prevalence of vitamin D deficiency and insufficiency, and to identify their main determinants in adults with T2D from the northern Dominican Republic.

Methods: Cross-sectional pilot study of 100 adults with T2D from public and private centers. Serum 25-hydroxyvitamin D [25(OH)D] was classified as deficiency ( < 20 ng/mL), insufficiency (20–29.9), or sufficiency (≥30). We collected sociodemographic data, solar exposure behavior, dietary frequency of vitamin-D–rich foods, anthropometry (BMI, waist circumference), and biochemistry. Comparisons used Mann-Whitney, Kruskal-Wallis, and chi-square tests; associations used Spearman's rho.

Results: Mean age 57.4 ± 13.1 years; 64% women. Mean 25(OH)D was 28.3 ± 9.0 ng/mL. Suboptimal levels were found in 64% of participants: deficiency 17.0% (95%CI 10.9–25.5) and insufficiency 47.0% (95%CI 37.5–56.7). Status was not associated with sex or age (p>0.20). Solar exposure variables showed biologically coherent but non-significant trends. In contrast, adiposity showed a robust inverse association with 25(OH)D (rho=-0.37, p< 0.001): mean levels declined from 32.3 ng/mL in normal weight to 20.5 ng/mL in class III obesity, with deficiency prevalence rising from 4.8% to 50.0% (χ²=22.92, p=0.028; Kruskal-Wallis H=13.92, p=0.008). Obese patients (BMI≥30) had lower 25(OH)D (24.8 vs 30.1 ng/mL; p=0.001) and higher deficiency prevalence (31.4% vs 10.0%; OR 4.12; 95%CI 1.37–12.45). Waist circumference also correlated inversely with 25(OH)D (rho=-0.23, p=0.021).

Conclusions: In this tropical Caribbean T2D cohort, two-thirds showed suboptimal vitamin D status despite high-UVB residence. Adiposity —not solar behavior— emerged as the dominant determinant, supporting the adipose-sequestration hypothesis. 25(OH)D screening should be prioritized in obese T2D patients in tropical settings. These pilot findings warrant confirmation in a larger multicenter cohort currently under recruitment.

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