Type 1 diabetes as a risk factor for impaired vitamin D status in a multi-ethnic cohort of canadian adolescents

Objectives: To evaluate type 1 diabetes as a risk factor for vitamin D status in an established, multi-ethnic adolescent cohort in relation to a healthy Canadian population. Methods: A total of 271 subjects, 12 to 18 years of age, with established type 1 diabetes mellitus, were recruited for this cross-sectional study. Demographic and clinical data were collected, and 25-hydroxyvitamin D (25-OHD) levels using liquid chromatography-mass spectrometry (LC-MS/MS) were measured. Normative Canadian-based population data were used as a reference group. Results: Lower rates of vitamin D sufficiency were observed in adolescents with type 1 diabetes when compared to healthy Canadian adolescents. For the type 1 diabetes group 14.0% of subjects were vitamin D sufficient (>75.0 nmol/L) and 32.8% were deficient (≤37.5 nmol/L), compared to 35.2% and 11.8%, respectively in the Canadian reference population (p<0.05). Caucasian subjects with type 1 diabetes had significantly higher vitamin D sufficiency levels (32.7%) compared to Hispanic (17.6%), South Asian (9.1%), Asian (7.1%), African-Canadian (4.2%) and mixed ethnicity (9.1%) groups (p<0.05). There was a strong association between ethnicity and vitamin D deficiency when adjusting for age, sex, body mass index (BMI) and glycated hemoglobin (A1C) (p<0.0001). Lastly, systolic blood pressure was higher in the vitamin D deficient group (p<0.05). Conclusions: These results indicate that type 1 diabetes is an independent risk factor for vitamin D deficiency beyond initial diagnosis and that ethnicity plays a significant role. Given that adolescence is a critical period of accrual of bone mass and progression of diabetes complications, consideration should be given for promotion of a vitamin D fortified diet or routine supplementation particularly in visible minorities with type 1 diabetes.