As always, my fellow blogger, Ann Bartlett, keeps me up to date with the latest rumors or information in the diabetes world and pointed me to the following: "GOT MILK" is a campaign that began in California and is now internationally known about the benefits of drinking milk. In this press release, it was noted that the campaign wishes to expand its message to say, "Vitamin D helps fight juvenile diabetes and along with sun exposure could reduce the risk of developing type 1 diabetes."

I went straight to the Diabetologia (2008) 51: 1391-1398 reference noted in the release. The article was written by Mohr, Garland et.al and called "The association between ultraviolet B irradiance, vitamin D status and, incidence rates of type 1 diabetes in 51 regions worldwide." Indeed, the information was very thought provoking. The authors of the study analyzed the relationship between ultraviolet B irradiance (the primary source of human Vitamin D) and age-standardized incidence rates of type 1 diabetes in children based on world location. The results of the study noted higher incidence rates in regions with higher latitudes and these rates were statistically significant (p<0.001). The authors concluded that there was an association between low Vitamin D exposure and high incidence rates of type 1 diabetes in children. Most interestingly, incidence levels approached zero in regions with high ultraviolet irradiance (vit D exposure). Thus, does Vitamin D (by ingestion or exposure to ultraviolet irradiance) reduce the risk of type 1 diabetes?

According to the authors, "The low incidence rate of type 1 diabetes in regions close to the equator indicates that there is potential for substantial reduction in incidence rates at higher latitudes." Not surprisingly, the highest incidence of type 1 diabetes was in Finland, Sardinia, Italy, Aberdeen of UK, Prince Edward Island (Canada), Sweden, and Norway. Previous studies unsuccessfully attempted to link milk protein produced by cows in Scandinavia to the etiology for the high incidence of type 1 diabetes. As always, these studies provide epidemiological links to certain diseases but do not necessarily prove that decreased levels of serum 25 hydroxy Vitamin D cause type 1 diabetes. I have noted anecdotally that several of my patients have low serum 25 hydroxy Vitamin D levels after working them up for frequent bone fractures or other issues. Administration of Vit D with resultant normalized levels did not normalize blood sugar. Interestingly enough is that we do know that children/teens/adults are born with the predisposition to develop type 1 diabetes based on the HLA locus (DR/DQ) regions. We also know that there needs to be an environmental trigger that allows for the autoimmune destruction of pancreatic islet cells. Perhaps we should add decreased serum 25 hydroxy Vitamin D levels to the possible list of etiologic insults that may lead to the development of Type 1 Diabetes.

The association of serum concentrations of serum 25 hydroxy Vitamin D also may play a role in the development of Type 2 diabetes. According to an epidemiologic report in the latest issue of Diabetes Care (Volume 33, number 2, February, 2010), Drs. Zhao, Ford, and Li noted that "among American adults without physician-diagnosed diabetes, low concentrations of serum 25 hydroxy Vitamin D were associated with markers of increased insulin resistance." The role of parathyroid hormone in relation to insulin resistance would therefore require further investigation.