The Impact of Vitamin D Status on Glycemic Control in Saudi Children and Adolescents with Type 1 Diabetes Mellitus

Abstract This study aims to assess the 25-hydroxyvitamin D (25-OH VitD) status in children and adolescents with type 1 diabetes mellitus and to identify the correlation between 25-OH VitD levels and glycosylated hemoglobin (HbA1c) levels. A cross-sectional study was conducted in the King Abdulaziz Medical City, Jeddah, Saudi Arabia. The study included 146 eligible patients. Serum 25-OH VitD < 50 nmol/L indicated below normal vitamin D level. All participants were Saudis, 63.0% were children, and 37.0% were adolescents (52.7% were male and 47.3% were female). The mean of HbA1c levels was 9.85 ± 1.79% and 25-OH VitD levels was 35.54 ± 13.88 nmol/L. The prevalence of 25-OH VitD inadequacy was 84.2%, with a mean 25-OH VitD levels of 31.22 ± 9.82 nmol/L. There was no significant correlation between 25-OH VitD levels and HbA1c levels (p = 0.14). On the other hand, the correlation was significantly negative between 25-OH VitD levels and daily insulin dose (p < 0.001), diabetes duration (p < 0.001), age (p < 0.001), and body mass index (p = 0.001), while it was significantly positive with dairy products intake per mL per day (p < 0.001). Furthermore, multiple regression analysis demonstrated that age, daily insulin dose, and gender were the factors that were associated adversely and significantly with 25-OH VitD levels (p = 0.001, p = 0.008, p = 0.002), respectively. Although vitamin D levels did not correlate significantly with HbA1c levels in this study, the findings of a significant inverse correlation of vitamin D levels with insulin requirements, in addition to a high prevalence of vitamin D levels inadequacy in children and adolescents with T1DM, indicate the importance of maintaining adequate vitamin D levels in this population.