Diminished 1,25-dihydroxyvitamin D with preserved 25-hydroxyvitamin D levels in 10-18-year-old youth with new-onset type 1 diabetes

Aim: Vitamin D inadequacy has been linked to onset, progression, and complications of type 1 diabetes. We aimed to further clarify the role of vitamin D metabolites in onset of type 1 diabetes. Methods We performed a cross-sectional comparison of 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) levels in 290 children (<10 years old) and youth/teens (10-18 years old) with new-onset or established type 1 diabetes and age-matched controls. Results25(OH)D levels (corrected for sex, season, race/ethnicity, and z-BMI) were significantly higher in children (n = 97) than in youth/teens (n = 193) (28.4 vs. 23.8 ng/mL, p <0.0001); 1,25(OH)2D levels did not differ between children and youth/teens. Among children, new-onset patients and controls had similar 25(OH)D and 1,25(OH)2D levels. Among youth/teens, mean corrected 25(OH)D level was significantly higher in new-onset patients (26.2 ng/mL) than established patients (23.3 ng/mL, p = 0.03) and controls (23.1 ng/mL, p = 0.01). The proportion of youth/teens with deficient 25(OH)D was 10 % in new-onset patients, 24 % in established patients, and 35 % in controls (new-onset vs. controls, p = 0.006). Among youth/teens, mean 1,25(OH)2D level was significantly lower in new-onset patients (50.8 pg/mL, p = 0.0002) and established patients (55.5 pg/mL, p = 0.02) than controls (62.1 pg/mL). 25(OH)D inadequacy was common but was not associated with new-onset type 1 diabetes. Lower 1,25(OH)2D levels in youth/teens with new-onset type 1 diabetes, compared with established patients and controls, suggest that the active vitamin D metabolite may be an environmental factor related to onset of type 1 diabetes in the second decade of life. Further studies are needed. © Springer International Publishing Switzerland 2017.