Vitamin D Deficiency in Obese Children and Its Relationship to Glucose Homeostasis

Objectives: The aim of the study was to compare the prevalence of vitamin D deficiency in obese and non-overweight children in North Texas, to examine relationships between dietary habits and 25-hydroxyvitamin D [25(OH) D] level in obese children, and to examine the relationship between 25(OH) D level and markers of abnormal glucose metabolism and blood pressure. Patients and Methods: Using a cross-sectional design, systolic and diastolic blood pressure, dietary information, serum 25(OH) D, fasting glucose and insulin, 2-h glucose from oral glucose tolerance test, hemoglobin A1c, and homeostasis model assessment of insulin resistance were recorded for 411 obese subjects (6-16 yr old) at an obesity referral clinic. 25(OH) D was also obtained from 87 control non-overweight subjects (6-16 yr old). Results: Ninety-two percent of obese subjects had a 25(OH) D level below 75 nmol/liter, and 50% were below 50 nmol/liter. Amongnon-overweight subjects, these frequencies were 68 and 22%, respectively (both P < 0.01 compared with obese subjects). 25(OH) D was negatively associated with soda intake (P < 0.001), juice intake (P = 0.009), and skipping breakfast (P < 0.001). 25(OH) D was negatively correlated with homeostasis model assessment of insulin resistance (r = - 0.19; P = 0.001) and 2-h glucose (r = -0.12; P = 0.04) after adjustment for body mass index and age but was not correlated with hemoglobin A1c, systolic blood pressure Z score, or diastolic blood pressure Z score. Conclusions: Vitamin D deficiency is commonin children in this southern United States location and is significantly more prevalent in obese children. Lower 25(OH) D level is associated with risk factors for type 2 diabetes in obese children. (J Clin Endocrinol Metab 97: 279-285, 2012)