title: A novel approach localizes the association of vitamin D status with insulin resistance to one region of the 25-hydroxyvitamin D continuum.
abstract: Vitamin D status has been implicated in insulin resistance, type 2 diabetes mellitus, and hypertension, but the range of vitamin D status values over which the association can be found is unknown. Our objective was to define this range in a cohort of nondiabetic adult Canadians. We used a regression modeling strategy, first adjusting insulin-response variables and systolic and diastolic blood pressure for BMI, waist circumference, weight, age, and sex. The resulting residuals were regressed against serum 25-hydroxyvitamin D [25(OH)D] concentration using successive 40% data blocks ranging from the 0th to the 60th percentile of 25(OH)D values. All of the predictor variables were significantly associated with each of the dependent variables, with BMI and waist circumference accounting for >98% of the explained variance. The vitamin D association was localized to the serum 25(OH)D range extending from ∼40 to ∼90 nmol/L (16-36 μg/L). We conclude that vitamin D status is inversely associated with insulin responsiveness and blood pressure. Consistent with the threshold response characteristic typical of nutrients, the association was strongest in a circumscribed region of the range of 25(OH)D values. There was no association at 25(OH)D values >80-90 nmol/L (32-36 μg/L), indicating that the vitamin D association applied principally to values below that level. The differences observed, if they can be further confirmed in prospective studies, are of a magnitude that would be clinically important.
authors.affiliation: Creighton University, Omaha, NE, USA. rpheaney@creighton.edu
authors.forename: Robert P
authors.initials: RP
authors.lastname: Heaney
authors.forename: Christine B
authors.initials: CB
authors.lastname: French
authors.forename: Stacie
authors.initials: S
authors.lastname: Nguyen
authors.forename: Mia
authors.initials: M
authors.lastname: Ferreira
authors.forename: Leo L
authors.initials: LL
authors.lastname: Baggerly
authors.forename: Ludovic
authors.initials: L
authors.lastname: Brunel
authors.forename: Paul
authors.initials: P
authors.lastname: Veugelers
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology*; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D002170:Canada; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012307:Risk Factors; D012737:Sex Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055105:Waist Circumference / Q000502:physiology; D055815:Young Adult
chemical_list: D007328:Insulin; D014807:Vitamin D; C104450:25-hydroxyvitamin D