title: Associations between Vitamin D Status and Type 2 Diabetes Measures among Inuit in Greenland May Be Affected by Other Factors.
abstract: OBJECTIVE
  Epidemiological studies have provided evidence of an association between vitamin D insufficiency and type 2 diabetes. Vitamin D levels have decreased among Inuit in Greenland, and type 2 diabetes is increasing. We hypothesized that the decline in vitamin D could have contributed to the increase in type 2 diabetes, and therefore investigated associations between serum 25(OH)D3 as a measure of vitamin D status and glucose homeostasis and glucose intolerance in an adult Inuit population.
  
  
  METHODS
  2877 Inuit (≥18 years) randomly selected for participation in the Inuit Health in Transition study were included. Fasting- and 2hour plasma glucose and insulin, C-peptide and HbA1c were measured, and associations with serum 25(OH)D3 were analysed using linear and logistic regression. A subsample of 330 individuals who also donated a blood sample in 1987, were furthermore included.
  
  
  RESULTS
  After adjustment, increasing serum 25(OH)D3 (per 10 nmol/L) was associated with higher fasting plasma glucose (0.02 mmol/L, p = 0.004), 2hour plasma glucose (0.05 nmol/L, p = 0.002) and HbA1c (0.39%, p<0.001), and with lower beta-cell function (-1.00 mmol/L, p<0.001). Serum 25(OH)D3 was positively associated with impaired fasting glycaemia (OR: 1.08, p = 0.001), but not with IGT or type 2 diabetes.
  
  
  CONCLUSIONS
  Our results did not support an association between low vitamin D levels and risk of type 2 diabetes. Instead, we found weak positive associations between vitamin D levels and fasting- and 2hour plasma glucose levels, HbA1c and impaired fasting glycaemia, and a negative association with beta-cell function, underlining the need for determination of the causal relationship.
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.
authors.forename: Nina O
authors.initials: NO
authors.lastname: Nielsen
authors.affiliation: National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.|Greeenland Centre for Health Research, University of Greenland, Nuuk, Greenland.
authors.forename: Peter
authors.initials: P
authors.lastname: Bjerregaard
authors.affiliation: Steno Diabetes Centre, Gentofte, Denmark.|Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: Pernille F
authors.initials: PF
authors.lastname: Rønn
authors.affiliation: Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Friis
authors.affiliation: Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Stig
authors.initials: S
authors.lastname: Andersen
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
authors.affiliation: Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Marika
authors.initials: M
authors.lastname: Lundqvist
authors.affiliation: Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Arieh S
authors.initials: AS
authors.lastname: Cohen
authors.affiliation: Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: David M
authors.initials: DM
authors.lastname: Hougaard
authors.affiliation: Steno Diabetes Centre, Gentofte, Denmark.|National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark.
authors.forename: Marit E
authors.initials: ME
authors.lastname: Jørgensen
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D005260:Female; D018149:Glucose Intolerance / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D005951:Glucose Tolerance Test; D006116:Greenland / Q000453:epidemiology; D006801:Humans; D004930:Inuit; D008297:Male; D008875:Middle Aged; D011236:Prediabetic State / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D012307:Risk Factors; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000150:complications*; D014815:Vitamins / Q000097:blood; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D014815:Vitamins; D014807:Vitamin D