Hepatic dysfunction is associated with vitamin D deficiency and poor glycemic control in diabetes mellitus

The effect of the rising prevalence of nonalcoholic fatty liver disease on the 25-hydroxylation of pre-vitamin D in the liver, and consequent glycemic control in children with diabetes mellitus is not known. Our aim was to determine whether mild hepatic dysfunction was associated with impaired 25-hydroxylation of pre-vitamin D, and if this vitamin D deficiency was associated with impaired glycemic control in children and adolescents with type 1 diabetes (T1DM) and type 2 diabetes (T2DM).

We analyzed simultaneously measured HbA1c, ALT, AST, and 25OHD levels and clinical parameters in 121 children and adolescents with T1DM (n=81) and T2DM (n=40). The subjects, ages 11-21 years, all had diabetes of >6 months duration. Multivariate linear regression was used to analyze the associations, while comparisons between subgroups were made using two-tailed Student's t-test.

Vitamin D deficiency (25OHD <15 ng/mL (37.5 nmol/L) was more prevalent in T2DM patients (47.5%) compared to T1DM patients (18.5%). Subjects with T2DM had significantly elevated transaminases (AST 39.3 +/- 2.0 vs. 22.4 +/- 1.4, p<0.001; ALT 30.6 +/- 1.8 vs. 18.7 +/- 1.3, p<0.001) compared to TIDM patients, and demonstrated a significant inverse relationship between their HbA1c and 25OHD levels (beta=-0.42, p=0.02), compared to T1DM subjects (beta=-0.06, p=0.62).

The association of elevated ALT with vitamin D deficiency suggests that hepatic dysfunction could impair vitamin D metabolism and negatively impact glycemic control in youth with T2DM.