Serum 25(OH)D Concentrations are Associated with the Glycemic Status and Insulin Resistance among Adults in Southwest China

Objective We aim to examine whether a higher serum 25(OH)D was associated with a more favorable glucose homeostasis among adults in Southwest China. Methods A total of 920 non‐diabetic adults (62.61% women) aged 25–65 years were recruited from an ongoing prospective study conducted in Southwest China between March and October, 2015. Data on dietary intake and physical activity were collected by validated questionnaires. Investigated metabolic factors for describing glucose homeostasis included fasting plasma glucose (FPG), insulin, glycated hemoglobin (HbA 1 c), the homeostatic model assessment‐insulin resistance (HOMA2‐IR) and prevalence of pre‐diabetes (impaired glucose tolerance and (or) impaired fasting glucose). Waist circumstance (WC), height and weight were measured, and the last two were used to calculate body mass index (BMI). Multivariable linear regression analyses were performed to examine the association between serum 25(OH)D concentrations and glucose homeostasis. Multivariable logistic regression analyses were used to examine the relation between serum 25(OH)D concentrations and the prevalence of pre‐diabetes. Results Serum 25(OH)D concentrations were inversely associated with fasting insulin (β=−0.041, p=0.0007), HbA 1 c (β=−0.0041, p=0.0001) and HOMA2‐IR (β=−0.0054, p=0.0007), but not with FPG, after adjusting for age, gender, personal monthly income, vocation, smoking status, energy intake, physical activity and WC. That is, each ng/mL increment in 25(OH)D concentration was associated with about 0.041μIU/mL for fasting insulin, 0.41% for HbA 1 c and 0.0054 for HOMA2‐IR increased, respectively. Furthermore, higher serum 25(OH)D level was a protective factor of pre‐diabetes (OR (95%CI): 0.982 (0.970, 0.995)) after adjusting for the confounders mentioned above. Conclusion Our results support that a higher serum 25(OH)D concentrations are associated with decreased risk of pre‐diabetes by mechanism likely tied to effects on insulin sensitivity in Chinese population. Support or Funding Information All phases of this study were supported by research grant from the National Nature Science Foundation of China (No.81472976).