Association Between Serum 25(OH)D Concentrations and Glucose-Lipid Metabolism in Women with Gestational Diabetes Mellitus: Analysis of A NHANES 2007-2018.

Vitamin D is implicated in multiple metabolic processes, however, the dose-dependent relationship between serum 25-hydro-xyvitamin D [25(OH)D] concentrations and glucose-lipid metabolism remains unclear among women with a history of gestational diabetes mellitus (GDM). This study aimed to assess both linear and non-linear relationships between serum 25(OH)D levels and indicators of insulin resistance and lipid metabolism in this high-risk group. Data from 1,876 women with prior GDM were obtained from the 2007-2018 National Health and Nutrition Examination Survey (NHANES). Weighted linear regression models were applied to assess associations between serum 25(OH)D and metabolic markers, while restricted cubic spline models were used to examine non-linear relationships. Analyses were adjusted for age, ethnicity, body mass index (BMI), education, and lifestyle factors. Following multivariate adjustment, each 10 nmol/l increase in serum 25(OH)D was associated with a decrease in HOMA-IR by 0.017 units (95 % CI: -0.026, -0.007), an increase in HDL-C by 0.127 mg/dl (95 % CI: 0.102, 0.153), and a reduction in total cholesterol of 0.007 mmol/l (95 % CI: -0.009, -0.004). Restricted cubic spline analysis demonstrated a U-shaped relationship between 25(OH)D and LDL-C (p for non-linearity<0.001), with inflection point at ~50 nmol/l. The inverse association between 25(OH)D and HOMA-IR was significant in non-Hispanic white individuals (beta=-0.020, p=0.008) but not in non-Hispanic Black individuals (beta=0.009, p=0.584). The positive association between 25(OH)D and HDL-C was strongest in women with normal BMI (beta=0.114). Among women with a history of GDM, serum 25(OH)D levels were inversely associated with insulin resistance and positively associated with HDL-C. A non-linear, U-shaped relationship was observed with LDL-C. These associations varied by race/ethnicity and BMI, the potential relevance of vitamin D status in in the long-term metabolic management of individuals following GDM. Key words 25-hydroxyvitamin D " Dose-response relationship " Gestational diabetes mellitus " Insulin resistance " Lipid metabolism.