Yes, Vitamin D deficiency is common in many chronic diseases, including diabetes. Like many here, I also tested as “extremely” VitD deficient several months ago and have been taking supplements ever since (2000IU/d now). Most physicians now recommend a level between 32.0 - 100 for optimal health (reference: Hollis BW. J Nutr. 2005 Feb; 135(2):317-22).
Vit D is sort of the new “it” vitamin in medicine. Besides the well known diseases associated with Vit D such as Rickets (which is almost unheard of now in the US), Vit D has now been implicated in everything from diabetes, to cancer, to cardiovascular disease. Using the definition of 30 as an optimal bottom level for Vit D, it is estimated that approximately 1 billion people worldwide are deficient in Vit D.
Since this is a diabetes forum, I’ll briefly mention the research in that area. Several studies have demonstrated that Vit D supplementation in children reduces the incidence of T1D and that increasing Vit D during pregnancy will reduce islet cell autoantibodies in offspring. In one such study done in Finland, 10,366 children were given Vit D supplementation of 2000IU per day during their first year of life. These children were followed for 31 years and the researchers showed that the risk of T1D in this group was reduced by approximately 81%. In the children who were Vit D deficient, on the other hand, risk was increased almost 200%. Studies have also demonstrated that daily calcium and vit D intake can reduce the risk of developing Type II diabetes in adults.
Most authorities would agree that it is basically impossible to get the correct amount of Vit D from diet and sunlight alone, while balancing the risks associated with sun exposure. Unless someone is eating a very large amount of fish or fish oil, it is unlikely that they will meet the optimal levels of Vit D from diet alone. With more and more Vit D research emerging, I expect that Vit D will become the new Vit C – a staple in everyone’s medicine cabinet.
References (for those who like that sort of thing):
Chiu KC, Chu A, Go VLW, Saad MF. Hypovitaminosis D is associated with insulin resistance and β cell dysfunction. Am J Clin Nutr 2004;79:820-5.
Hypponen E, Laara E, Reunanen A, Jarvelin M-R, Virtanen SM. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet 2001;358:1500-3.
(for anyone who is interested, there is a great (but highly technical) review article on Vitamin D from the NEJM that I would be happy to send to you if you’re so inclined.)