HOW DOES INSULIN RESISTANCE AFFECT VITAMIN D LEVELS IN OBESE CHILDREN AND ADOLESCENTS

Abstract

Badriah Gharamah Al Asmari*, Najmah Ali Eidah Alotaibi, Abrar Abdullah Ali Alghamdi, Assma Khaled Salwy, Waleed Khallufah Saad Qubayl, Mansour Hajed Musheh Al-Harthi, Asmaa Salah Ghmaird, Walaa Abduraheem Abuharba, Abdulaziz Mashan Almutairi, Khaled Hatem Kariri and Smaher Abdullah Bahawi

Background: Childhood obesity is a growing global concern, often linked to metabolic disorders such as insulin resistance and vitamin D deficiency. Research suggests an inverse relationship between vitamin D levels and insulin resistance, but the underlying mechanisms remain unclear. This study aims to investigate the impact of vitamin D supplementation on insulin resistance in overweight and obese children and adolescents.

Methods: This study was conducted on 100 children and adolescents (aged 4–18 years) with a BMI above the 85th percentile and vitamin D deficiency (serum 25-hydroxyvitamin D < 20 ng/ml). Participants received vitamin D supplementation (50,000 IU weekly for 8 weeks, followed by 1,000 IU daily for 3 months). Pre- and postintervention assessments included BMI, fasting blood sugar (FBS), insulin levels, HOMA-IR index, and vitamin D levels. Statistical analysis was performed using SPSS, with significance set at p < 0.05.

Results: Following vitamin D supplementation, a significant increase in serum vitamin D levels (p < 0.001) and a reduction in BMI (p = 0.008) and FBS (p = 0.028) were observed. However, there were no significant changes in insulin levels (p = 0.143) or HOMA-IR index (p = 0.097). Post-intervention analysis revealed a negative correlation between vitamin D levels and BMI, insulin, HOMA-IR, and FBS.

Conclusion: Vitamin D supplementation effectively increased serum vitamin D levels and improved BMI and FBS in obese children and adolescents. However, it did not significantly impact insulin resistance within the study period. Longer intervention durations may be necessary to assess potential effects on insulin sensitivity.