Vitamin D levels in obese patients with and without metabolic syndrome
Savas Karatas, Zeliha Hekimsoy, Gönül Dinç, Ece Onur & Bilgin Özmen
Vitamin D role is not only associated with mineral metabolism and bone health but also in globally important diseases such as obesity and metabolic syndrome. The aims of this study were to investigate: i) 25(OH) vitamin D levels in obese patients with and without metabolic syndrome and compare these with levels in healthy subjects, ii) the relationship between serum 25(OH) vitamin D levels and metabolic syndrome components such as body mass index, waist circumference, blood pressure, fasting blood glucose, lipid parameters and insulin resistance (HOMA-IR). HOMA-IR was calculated as serum glucose (mg/dL)×insulin level (μU/ml)/405. Two hundred eighty-seven (n=287) subjects participated in the study: 94 obese patients with metabolic syndrome, 120 obese patients without metabolic syndrome and 73 non-obese patients without metabolic syndrome. Serum 25(OH) vitamin D deficiency, defined as a level <20 ng/ml, was more common in obese patients with (72.3%) and without (69.2%) metabolic syndrome versus control group (49.2%) (P=0.006). Serum 25(OH) vitamin D levels were significantly lower in obese metabolic syndrome patients (16.8±7.3 ng/ml) than in obese non-metabolic syndrome patients (18.3±8.6 ng/ml) and healthy subjects (21.2±8.9 ng/ml, P=0.001). A negative relationship was found between serum 25(OH) vitamin D levels and body mass index (r=−0.159, P=0.007) and serum triglyceride levels (r=−0.141, P=0.018). Serum 25(OH) vitamin D levels correlated inversely (not statistically significant) to waist circumference, fasting blood glucose, HOMA-IR, and blood pressure, but positively (not statistically significant) to HDL cholesterol levels. In conclusion, vitamin D deficiency is very common in obese patients, more so in patients with than in those without metabolic syndrome.