Youth with type 1 diabetes are at significant risk for vitamin D deficiency, based on results of a study of 128 children and adolescents.
Chronic vitamin D deficiency in childhood contributes to bone deformity and reduced bone mass, which could increase fracture risk in adulthood. Because previous research suggests that type 1 diabetes itself is associated with reduced bone mineral density, children and teens with type 1 diabetes may be at even greater risk for skeletal weakness, Dr. Britta M. Svoren of the Joslin (Mass.) Diabetes Center and colleagues noted in the Journal of Pediatrics (2009;154:132–4).
In this study, the researchers measured serum 25-hydroxyvitamin D (25[OH]D) in infants, children, and teens younger than 18 years with type 1 diabetes in the United States. Vitamin D sufficiency, insufficiency, and deficiency were defined as 25(OH)D levels of 30 ng/mL or higher, 21–29 ng/mL, and 20 ng/mL or lower, respectively.
Overall, only 31 participants (24%) met the criteria for sufficient vitamin D, while 78 (61%) had insufficient vitamin D, and 19 (15%) were vitamin D deficient.
When the children were divided into three age groups, 22% of adolescents aged 12–18 years were vitamin D deficient, compared with 12% of those aged 0–5 years and none of the children aged 6–11 years.
After investigators controlled for factors including age, sex, ethnicity, body mass index, and diabetes control (based on hemoglobin A1c measures), older age was significantly associated with lower 25(OH)D concentrations, and the mean 25(OH)D concentration was significantly lower in the oldest age group (12–18 years) at 24.2 ng/dL, compared with the youngest age group (0–5 years) at 30.8 ng/dL; those aged 6–11 years were in the middle with a mean 25(OH)D concentration of 26.8 ng/dL.
Ethnicity also was associated with lower 25(OH)D levels, which were significantly more common among nonwhites.
Adolescents with type 1 diabetes have additional risk factors for skeletal weakness, including hyperglycemia and hypercalciuria. Lifestyle factors such as drinking less milk and getting less sun exposure also can play a role. Consumption of sugar-free colas, which is common in teens with diabetes, is an additional risk factor for poor bone health because the beverages contain phosphoric acid, “which is known to reduce intestinal calcium absorption,” Dr. Svoren and her associates said.
“Many of these risk factors may not be modifiable because of the inherent presence of diabetes mellitus, [so] ensuring vitamin D sufficiency throughout childhood and during the time of maximal bone mineral accrual seems particularly warranted in this population,” they said.
Dr. Svoren and colleagues said that providers should monitor vitamin D in youth with type 1 diabetes and consider vitamin D supplements for those who aren't getting enough vitamin D through their diets.
The results support findings from previous studies showing evidence of vitamin D deficiency in children and adolescents with type 1 diabetes, but more research is needed to confirm the findings and identify the causes of vitamin D deficiency in this population, they said.
The study was funded by grants from the National Institutes of Health, the Charles H. Hood Foundation, and Eli Lilly & Co. The researchers reported that they had no relevant financial conflicts to disclose.