Objective: The purpose of this investigation was to examine serum vitamin D status in a population of Punjabi ancestry from Northern India with a high prevalence of type 2 diabetes (T2D) and evaluate the effects of 25(OH)D levels on cardio-metabolic traits.
Research design and methods: We assessed cardiovascular risk factors and 25(OH)D levels in 1,765 participants (887 T2D cases, 878 normoglycemic controls).
Results: 76% of individuals were deficient (<50 nmol/L) in vitamin D. A higher percentage of T2D participants(83%) were vitamin D deficient compared to normoglycemic controls (68%)(p<0.0001).The prevalence of vitamin D deficiency increased progressively with body mass index (BMI) categories (p<0.0001): BMI<23 kg/m2, 65%; BMI 23-27.5 kg/m2, 75%; and BMI>27.5 kg/m2, 81%. T2D participants had significantly decreased serum 25(OH)D levels (β=-0.41, p=2.8 × 10-20). Individuals with low serum 25(OH)D had elevated fasting glucose(β=-0.18, p=0.022), BMI (β=-0.71, p=1.4 × 10-7) and systolic blood pressure (β=-1.68, p=0.006). A positive association of increased 25(OH)D with HOMA-B (β=0.17, p=8.0×10-6), and C-peptide (β=0.09, 0.017) was observed. Non-medicated, normoglycemic, non-hypertensive individuals classified as vitamin D deficient (n=289) exhibited a significant increase in fasting glucose (p=0.02) and BMI (p<0.0001) as well as a significant decrease in C-peptide (p<0.0001) and amylin (p<0.0001) compared to vitamin D sufficient controls (n=150).
Conclusions: Vitamin D deficiency appears to be a significant risk factor for T2D severity and associated cardio-metabolic risk. Early intervention may be considered to improve prevention of T2D related cardiovascular complications.