Objective: To investigate the frequency and effects of vitamin D deficiency in children with type 1 diabetes (T1D) in a region which is known to have a high rate of vitamin D deficiency among adolescents.
Methods: In this prospective cross-sectional study, 120 children and adolescents with T1D (55 girls and 65 boys) aged 3-20 years were evaluated. Serum 25-hydroxyvitamin D [25(OH)D], parathormone (PTH), and alkaline phosphatase (ALP) levels were measured. Hemoglobin A1c levels and daily insulin requirement were also evaluated. Classification of vitamin D status was made according to the American Academy of Pediatrics (AAP)/LWEPS's recommendations. The patients were divided into 2 groups according to their vitamin D status and also according to the season of the year in which 25(OH)D sampling was done.
Results: Serum 25(OH)D levels revealed vitamin D deficiency or insufficiency in 38% of the patients. Higher PTH levels were found in the patient group whose mean 25(OH)D level was < 20 ng/mL as compared to the group whose mean 25(OH)D level was > 20 ng/mL (p < 0.05). Only 11% of patients had secondary hyperparathyroidism. The 25(OH)D levels of patients whose serum samples were taken in summer and spring months were significantly different (p < 0.05). There were no significant correlations between 25(OH)D level and daily insulin dose.
Conclusion: Although we could not show a significant association between vitamin D deficiency and metabolic parameters, the frequency of vitamin D deficiency in T1D children is substantial. Vitamin D status should be assessed also in patients who do not have signs of rickets.