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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Case-control study: Low vitamin D levels found at onset of type 1 diabetes

Researchers recently found vitamin D levels to be significantly lower among children with type 1 diabetes compared to children with other diseases.

Type I diabetes (T1D) is a type of diabetes usually diagnosed in childhood. T1D is an autoimmune disease in which the immune system attacks and destroys the body’s own insulin-producing beta cells. Unlike T2D, it is poorly understood how to prevent T1D.

Researchers have been interested in a possible link between vitamin D deficiency and T1D because of vitamin D’s beneficial role in immune functions. A recent meta-analysis, for example, found that babies receiving vitamin D supplements were 29% less likely to develop T1D later in life. Additionally, studies have found a gradient to T1D in relation to global latitude. Rates of T1D are low near the equator and much higher as you move away.

In the current study, researchers out of Italy conducted a case-control study, to see what the vitamin D levels of children were upon recent diagnosis of T1D, and how those levels compared to children without T1D.

Fifty-eight children with recent diagnosis of T1D participated in the study. Among the 58 children with T1D, 29 patients were included who had diabetic ketoacidosis. Diabetic ketoacidosis is a serious complication of diabetes that occurs when the body has low levels of insulin. Without insulin, the body breaks down fat because of the need for fuel. This produces a buildup of acids in the bloodstream which can lead to rapidly developed symptoms of shortness of breath, abdominal pain, and weakness, among other things.

For each child with T1D, researchers found 2 to 3 matched children with exact age, sex, and season of visit, which equaled 166 control participants. What makes this study particularly interesting is how they selected the control group. The researchers sought out not healthy children, but children admitted to the hospital with other various illnesses. These children were admitted to the hospital for conditions like respiratory infections, neurological diseases, renal failure, and skin infections. Such conditions have been associated with high incidence of vitamin D deficiency. So the question is, are children with T1D even more likely to have deficiency?

The researchers measured serum vitamin D levels of all children with T1D and the matched control group. Here’s what they found:

  • Median vitamin D levels for the T1D group and control group were 14.48 ng/ml and 19.48 ng/ml, respectively (p=0.010).
  • Median vitamin D levels for patients with diabetic ketoacidosis was 12.08 ng/ml, a level significantly lower than those without the complication (p=0.019).
  • Lower vitamin D levels were significantly associated with increased odds for developing T1D (OR=3.45, p<0.05).
  • There was no significance found between season and risk of developing T1D.

The researchers concluded,

“The results of our study confirm previous results observed in adults: in new-onset T1D, serum 25(OH)D levels at diagnosis were significantly lower in patients than in control subjects.”

The researchers note that limitations of the study include the lack of longitudinal analysis and limited number of patients. Additionally, even though vitamin D supplementation isn’t common among Italian children, no information on supplementation was gathered.

Further research is needed. It remains to be seen if a randomized controlled trial will be conducted to see if vitamin D supplementation during very early childhood can prevent T1D. Given its relatively rare incidence (in Finland, rates are very high, but still only at 64 cases per 100,000), it would be a difficult randomized controlled trial to fund and execute properly due to the number of children researchers would need to enroll. One suggested strategy is to conduct a randomized controlled trial on children who are genetically predisposed of developing T1D, to see if vitamin D can prevent or delay onset in this subset of children.


Franchi, B. et al. Vitamin D at the onset of type 1 diabetes in Italian children. European Journal of Pediatrics, 2013.

  About: Jeff Nicklas

Jeff Nicklas was a staff member for the Vitamin D Council from October 2013 to January 2015. He is now pursuing his passion for public health through graduate studies.