BACKGROUND: The effects of vitamin D supplementation on mild hepatic dysfunction and glycemic control are unclear in children and adolescents with either type 1 (T1D) or type 2 diabetes (T2D).

HYPOTHESIS: Vitamin D supplementation will improve hepatic dysfunction and glycemic control.

AIM: To determine the effect of vitamin D supplementation on alanine transaminase (ALT), hemoglobin A1c (HbA1c), and serum 25-hydroxyvitamin D [25(OH)D] concentration.

SUBJECTS AND METHODS: A retrospective study of 131 subjects with either T1D (n = 88∶46 females, 42 males), or T2D (n = 43∶26 females, 17 males) of ages 3-18 years between 2007-2013. All subjects had (1) a diagnosis of diabetes for >12 mo, (2) received vitamin D supplementation for the management of vitamin D deficiency (3) had baseline and subsequent simultaneous measurements of HbA1c, ALT, and 25(OH)D. Vitamin D deficiency was defined as 25(OH)D concentration of/L (20 ng/mL).

RESULTS: At baseline, vitamin D deficiency occurred in 72.1% of patients with T2D and in 37.5% of T1D patients (p

CONCLUSIONS: Vitamin D supplementation in subjects with T2D was associated with statistically significant decreases in BMI SDS, ALT, and a clinically-significant decrease in HbA1c.