Relationship between vitamin D and abdominal obesity in non-diabetic population in Taiyuan community

Objective To evaluate the serum 25-hydroxyvitamin D [25(OH)D3] levels in non-diabetic people in Taiyuan community, and its relationship with obesity and abdominal obesity. Methods This cross-sectional study enrolled 417 non-diabetic people in Tainyuan community from July to September in 2011 [225 males and 192 females, mean age (47.6±7.8) years]. For all the enrolled subjects, we collected data about anthropometric indexes, medical history, blood glucose, lipid profile, 25(OH)D3, fasting insulin (Fins) level, homeostasis model assessement for insulin resistance(HOMA-IR), body fat content (%) measured with dual-energy X-ray absorptiometry (DEXA), and intra-abdominal adipose tissue (IAAT) and abdominal subcutaneous adipose tissue (SCAT)calculated based on magnetic resonance imaging at the 4th to 5th lumbar disc level (IAAT≥80 cm2 was considered abdominal obesity). Correlation analysis was performed to assess the relationships of serum 25(OH)D3 levels with biochemical and body fat indexes. Results The average serum lev-el of 25(OH)D3 was 44.5 nmol/L in the 417 people, with vitamin D deficiency in 261 cases(62.6%) and vitamin D insufficiency in 109 cases(26.1%). Of the vitamin D deficient and insufficient people, 77.6% had abdominal obesity according to IAAT(IAAT≥80 cm2). According to Pearson analysis result, lg 25(OH)D3 was negatively correlated with lg Fins, lg HOMA-IR, waist circumference, systolic blood pressure, diastolic blood pressure, total abdominal adipose tissue (TAAT), IAAT (all P 0.05). In stepwise multiple linear regression model, lg HOMA-IR(t=-4.278, P=0.001) and TAAT(t=-5.146, P=0.002) were independently correlated with lg 25(OH)D3. Conclusions About 90% of all non-diabetic population in Taiyuan community have vitamin D deficiency or insufficiency, of whom 4/5 have abdominal obesity. Serum 25(OH)D3 level is negatively correlated with abdominal adipose tissue, but not significantly associated with BMI. HOMA-IR and TAAT are independent risk factors for vitamin D deficiency. Key words: Vitamin D; Abdominal obesity; Insulin resistance