Effect of intra-trial mean 25(OH)D level on diabetes risk, by race and weight: an ancillary analysis in the D2d study

Authors: CHATTERJEE, RANEE - Duke University; DAVENPORT, CLEMONTINA - Duke University; VICKERY, ELLEN - Tufts Medical Center; JOHNSON, KAREN - University Of Tennessee; KASHYAP, SANGEETA - Cleveland Clinic; LEBLANC, ERIN - Kaiser Permanente Center For Health Research; NELSON, JASON - Tufts Medical Center; DAGOGO-JACK, SAMUEL - University Of Tennessee; PITTAS, ANASTASSIOS - Tufts Medical Center; DAWSON-HUGHES, BESS - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2023
Publication Date: 7/1/2023
Citation: Chatterjee, R., Davenport, C.A., Vickery, E.M., Johnson, K.C., Kashyap, S.R., Leblanc, E.S., Nelson, J., Dagogo-Jack, S., Pittas, A.G., Dawson-Hughes, B. 2023. Effect of intra-trial mean 25(OH)D level on diabetes risk, by race and weight: an ancillary analysis in the D2d study. The American Journal of Clinical Nutrition. https://doi.org/10.1016/j.ajcnut.2023.03.021.
DOI: https://doi.org/10.1016/j.ajcnut.2023.03.021

Interpretive Summary: In a largely Caucasian population with prediabetes, we have previously found that participants who attained relatively high blood 25-hydroxyvitamin D levels in response to vitamin D supplementation had lower risk of developing type 2 diabetes. Vitamin D status varies in different populations, with a higher prevalence of vitamin D deficiency in people of color and in people with obesity. It is not known whether the blood level of 25-hydroxyvitamin D achieved during supplementation influences diabetes risk in people of color and in obese people. To answer this question, we analyzed data in the Vitamin D and Type 2 Diabetes (D2d) study cohort which included 616 Black and 1616 White participants and included both obese and non-obese participants. Both at entry and during the 3-year study, 25-hydroxyvitamin D levels were lower in Black vs. White participants and in obese vs non-obese participants. Black participants and obese participants who reached higher 25-hydroxyvitamin D levels during the study had significantly reduced risk of developing diabetes, and the reduction in risk was similar to that observed in White participants. This suggests that it is important for Black adults and obese adults as well as White adults and non-obese adults to maintain high-normal 25-hydroxyvitamin D levels in order to lower their risk of progression from prediabetes to type 2 diabetes.

Technical Abstract: Background: Higher serum 25-hydroxyvitamin D [25(OH)D] is associated with lower risk for type 2 diabetes. 25(OH)D varies due to skin color and weight. Objectives: We sought to determine if people of color and those who are overweight\obese, and who have higher risk of diabetes, have different associations between 25(OH)D and diabetes risk than individuals who are White and\or normal weight. Design: The D2d study is a randomized clinical trial in people with prediabetes that studied the effects of vitamin D3 4000 IU vs placebo taken daily on diabetes risk. In the D2d cohort, we compared baseline and intra-trial mean 25(OH)D levels among groups defined by self-reported race and body mass index (BMI). We used Cox proportional hazards models to assess associations between intra-trial mean 25(OH)D and diabetes risk by race- and BMI-based groups. Results: Black (n = 616), White (n = 1616), and Asian (n = 130) D2d participants were included in analyses. Both baseline and intra-trial mean 25(OH)D levels were lower in Black (and Asian vs. White participants (P /=40 ng\mL had significantly reduced diabetes risk [HR (95%CI)]: Black: 0.51 (0.29, 0.92); White 0.42 (0.30, 0.60)], with a similar reduction in diabetes risk among Asian participants [HR (95%CI) 0.39 (0.14, 1.11)].. Compared to those with lower levels, participants with baseline BMI <40 kg\m2 who achieved intra-trial mean 25(OH)D levels >/=40 ng\mL had a significantly reduced diabetes risk. There were no significant interaction effects by race or BMI. Conclusions: Among people with prediabetes, targeting a 25(OH)D level >/=40 ng\mL among individuals, including people of Black and White race, with a BMI <40 kg\m2 may optimize diabetes prevention efforts.