title: The relationship between low maternal serum 25-hydroxyvitamin D levels and gestational diabetes mellitus according to the severity of 25-hydroxyvitamin D deficiency.
abstract: OBJECTIVE
  To assess the relationship between low maternal serum 25-hydroxyvitamin D levels and gestational diabetes mellitus in Turkish pregnant women according to the severity of 25-hydroxyvitamin D deficiency and assess intact parathyroid hormone levels in women with gestational diabetes mellitus and controls with low and sufficient 25-hydroxyvitamin D levels.
  
  
  METHODS
  We analyzed serum 25-hydroxyvitamin D and intact parathyroid hormone levels in 234 women with gestational diabetes mellitus and 168 controls. To define the deficiency status, 25-hydroxyvitamin D levels were further classified into severely deficient, deficient, insufficient and sufficient groups.
  
  
  RESULTS
  Women with gestational diabetes mellitus had significantly lower 25-hydroxyvitamin D levels compared to controls (30.8±16.3 vs. 36.0±16.2 nmol/L). However, when subgroups of 25-hydroxyvitamin D were analyzed, gestational diabetes mellitus was significantly more common only in women with severely deficient 25-hydroxyvitamin D levels. After adjusting for covariates, only severely deficient 25-hydroxyvitamin D levels were independently associated with an increased relative risk of gestational diabetes mellitus. The relative risk of gestational diabetes mellitus in women with insufficient and deficient 25-hydroxyvitamin D levels was not statistically significant. Intact parathyroid hormone concentrations were also significantly higher in women with gestational diabetes mellitus compared to the controls (45.3±26.2 vs. 38.7±27.6 pg/ml).
  
  
  CONCLUSIONS
  The results obtained from this study provide novel data indicating that only severely deficient maternal serum 25-hydroxyvitamin D levels are significantly associated with an elevated relative risk of gestational diabetes mellitus, even after adjusting for established risk factors of gestational diabetes mellitus.
authors.affiliation: Endocrinology and Metabolism Department, Sisli Etfal Training and Research Hospital, Istanbul, Turkey. zuhur744@gmail.com
authors.forename: Sayid Shafi
authors.initials: SS
authors.lastname: Zuhur
authors.forename: Rumeysa Selvinaz
authors.initials: RS
authors.lastname: Erol
authors.forename: Idris
authors.initials: I
authors.lastname: Kuzu
authors.forename: Yuksel
authors.initials: Y
authors.lastname: Altuntas
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D016640:Diabetes, Gestational / Q000097:blood*; D005260:Female; D006801:Humans; D010281:Parathyroid Hormone / Q000097:blood; D011247:Pregnancy; D012720:Severity of Illness Index; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D