25-Hydroxyvitamin D is closely related with the function of the pancreatic islet β cells

Objectives: This study is to investigate the relationship between 25-Hydroxyvitamin D (25-OH-D) and pancreatic islet β cell function under different glucose tolerance statuses in China. Methodology: Totally, 180 patients with type 2 diabetes mellitus (DM group), 178 patients with impaired fasting glucose/impaired glucose tolerance (IFG/IGT group), and 160 normal control subjects (NGT group) were included to measure their body parameters and biochemical parameters. In oral glucose tolerance test, fasting serum 25-OH-D was assessed by the enzyme-linked immunosorbent assay (ELISA). Homeostasis model assessment for insulin resistance (Homa-IR), insulin acuity index (IAI), β-cell function index (Homa-BCF) as well as secretion index (IS) were determined. Results: The levels of 25-OH-D, IAI and Homa-BCF in the DM group and IFG/IGT group were significantly lower than that in NGT group (P < 0.05). Homa-IR in DM group and IFG/IGT group was significantly higher than that in the NGT group (P < 0.05). Pearson correlation analysis and partial correlation analysis showed that 25-OH-D was positively correlated with fasting insulin (FINS) and Homa-BCF (P < 0.05). Multiple stepwise regression analysis showed that 25-OH-D was one of the influential factors of pancreatic islet β cell function in patients with type 2 diabetes mellitus. Conclusions: Our results suggest that 25-OH-D is closely related with the function of the pancreatic islet β cells and is one of the influential factors of pancreatic islet β cell function.