Poster Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2016

Vitamin D is associated with adiposity and cardiometabolic risk factors in a predominantly vitamin D-deficient and overweight/obese but otherwise healthy cohort (#243)

Aya Mousa 1 , Negar Naderpoor 1 2 , Maximilian PJ de Courten 3 , Robert Scragg 4 , Barbora de Courten 1 2
  1. Monash Centre for Health Research and Implementation, School of Public Health and Preventive Medicine, School of Public Health and Preventive Medicine, Melbourne, VIC, Australia
  2. Diabetes & Vascular Medicine Unit, Monash Health, Melbourne, VIC, Australia
  3. Centre for Chronic Diseases, Victoria University, Melbourne, VIC, Australia
  4. School of Population Health, The University of Auckland, Auckland, New Zealand

BACKGROUND: Vitamin D deficiency has reached epidemic proportions worldwide and has recently been linked to cardiometabolic risk factors including obesity, insulin resistance, hypertension, dyslipidemia as well as type 2 diabetes and cardiovascular disease. OBJECTIVE: The objective of this study was to examine the associations between circulating vitamin D levels and cardiometabolic risk factors using direct measures of adiposity, glucose intolerance, and insulin resistance, as well as lipids, blood pressure, and plasma markers of inflammation. METHODS: We measured circulating 25-hydroxyvitamin D3; physical activity (International Physical Activity Questionnaire); anthropometry (BMI, WHR, %body fat (dual energy X-ray absorptiometry)); metabolic parameters (fasting and 2-hour glucose during OGTT; insulin sensitivity (M, hyperinsulinaemic-euglycaemic clamp), and cardiovascular and inflammatory profiles (blood pressure (BP), lipids, white blood cell count (WBC), and plasma high-sensitivity C-reactive protein levels (hsCRP)) in 111 healthy, non-diabetic adults (66M/45F; age=31.1±9.2 years; %body fat=36.0±10.2%). RESULTS: Mean 25OHD was 39.8±19.8 nmol/L with no gender differences (p=0.4). On univariate analysis, vitamin D was associated with %body fat (r=-0.27;p=0.005), 2-hour glucose (r=-0.21;p=0.03), and insulin sensitivity (r=0.20;p=0.04), but not with age, BMI, WHR, fasting glucose, BP, lipids, or inflammatory markers (all p>0.05). After adjusting for age and sex, vitamin D remained associated with %body fat (β=-0.24;R2=0.38;p=0.003), 2-hour glucose (β=-0.22;R2=0.06;p=0.02), and insulin sensitivity (β=0.21;R2=0.05;p=0.03), and became associated with fasting glucose (β=-0.19;R2=0.10;p=0.04) and hsCRP (β=-0.21;R2= 0.12;p=0.04). After adjusting for age, sex, and %body fat, vitamin D was only associated with fasting glucose (β=-0.21;R2= 0.11;p=0.03), which persisted after hsCRP and physical activity were added to the model (β=-0.24;R2=0.15;p=0.02).​ CONCLUSION: These cross-sectional data suggest that associations between vitamin D and glucose metabolism among healthy non-diabetic adults are largely mediated by adiposity with no association with cardiovascular risk factors. Large-scale intervention and mechanistic studies are needed to further investigate whether vitamin D has an independent role in the prevention and/or management of cardiometabolic risk and disease.