Low Levels of 25‐Hydroxy Vitamin D and Active 1,25‐Dihydroxyvitamin D Independently Associated with Type 2 Diabetes Mellitus in Older Australian Men: The Concord Health and Ageing in Men Project

Objectives To examine the associations between serum 25‐hydroxyvitamin D (25 OHD ) levels and the active vitamin D metabolite, 1,25‐hydroxyvitamin D (1,25 OHD ), with type 2 diabetes mellitus ( DM ) in community‐living men aged 70 and older. Design Cross‐sectional. Setting A population‐based, cross‐sectional analysis of the baseline phase of the Concord Health and Ageing in Men Project ( CHAMP ), a large epidemiological study conducted in Sydney between January 2005 and May 2007. Participants Community dwelling men aged 70 and older taking part in CHAMP (N = 1,659). Measurements Serum 25 OHD and 1,25 OHD levels, presence of DM , age, country of birth, season of blood collection, sun exposure, body mass index, vitamin D supplement use, statin use, income, measures of health, depression, activity of daily living disabilities, parathyroid hormone, estimated glomerular filtration rate, phosphate, and calcium. Results The prevalence of DM was 20.0%. There was a significant association between low 25 OHD and 1,25 OHD levels and DM that remained after adjustment for a wide range of confounders and covariates of clinical significance such as comorbidity, renal function, calciotropic hormones, and medications. Conclusion 25 OHD and 1,25 OHD levels were associated with DM . The independent association between serum 25 OHD and 1,25 OHD concentrations and DM raises the question of whether each of the two vitamin D metabolites may influence DM through different biological mechanisms and pathways.