Effect of Vitamin D on Insulin Resistance in Overweight and Obese Children and Adolescents With Vitamin D Deficiency

Obesity is one of the major health issues in developed and developing countries, which has been increasing in recent decades. Obesity is one of the important risk factors for type 2 diabetes by developing insulin resistance. The purpose of this study was to investigate the effect of vitamin D on insulin resistance in overweight and obese children and adolescents with vitamin D deficiency. In this interventional study, 53 overweight and obese children and adolescents with vitamin D deficiency referred to the Endocrinology Clinic of Shahrekord University of Medical Sciences were included. The height and weight of participants were measured, and their Body Mass Index (BMI) calculated. To participants, 50,000 units of vitamin D were administered weekly for 8 weeks, and then 1000 units were orally administered daily for 3 months. Before and after the intervention, levels of vitamin D, insulin, and fasting blood sugar were measured. The HOMA-IR was also calculated as an indicator of insulin resistance. After the intervention, serum vitamin D significantly increased, and BMI and fasting blood sugar significantly decreased (P<0.05). The insulin resistance index did not change significantly during the intervention (P>0.05). After the intervention, HOMA-IR had a significant direct correlation with body mass index, insulin, and fasting blood sugar and a significant inverse correlation with vitamin D (P<0.05). Vitamin D had a significant inverse correlation with BMI, insulin, and fasting blood sugar after the intervention (P<0.05). Oral treatment with vitamin D significantly increased serum vitamin D levels and significantly decreased BMI and fasting blood sugar in obese and overweight children.