title: 25-Hydroxyvitamin D is closely related with the function of the pancreatic islet β cells.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
authors.affiliation: Jingjing Guo, School of Medicine, Department of Endocrinology, Jinan Central Hospital Affiliated to Shandong University, Jinan, 250013, P R China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Guo
authors.affiliation: Zhengda Xiao, Department of Endocrinology, Jinan Central Hospital Affiliated to Shandong University, Jinan, 250013, P R China.
authors.forename: Zhengda
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: Xia Xue, Department of Endocrinology, Jinan Central Hospital Affiliated to Shandong University, Jinan, 250013, P R China.
authors.forename: Xia
authors.initials: X
authors.lastname: Xue
authors.affiliation: Xin Liu, Beijing University of Chinese Medicine, Beijing, 100029, P R China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Yong Lu, Department of Endocrinology, Jinan Central Hospital Affiliated to Shandong University, Jinan, 250013, P R China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Xiao Yin, Department of Endocrinology, Jinan Central Hospital Affiliated to Shandong University, Jinan, 250013, P R China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yin
authors.affiliation: Kun Ma, School of Medicine, Shandong University, Jinan, 250012, P R China.
authors.forename: Kun
authors.initials: K
authors.lastname: Ma
keywords: Diabetes mellius; Pancreatic islet β cell; Type 2; Vitamin D