Can vitamin D and sunlight exposure prevent type-two diabetes?

There are two types of diabetes: type-1 and type-2. Type-1 is generally known as “juvenile” diabetes, and type-2 is known as adult-onset diabetes. In type-2 diabetes (90% of all diabetes), insulin is sometimes necessary, but the real reason for the disease is the body’s inability to use its own insulin (insulin resistance).

Diabetes is increasing out-of-control as the population becomes increasingly obese and increasingly avoids the sunlight. During the 1990s, obesity increased by 61% and type-2 diabetes increased by 49%.[1] In 2007, the health-care and lost-productivity costs of diabetes were $174 billion, an increase of $42 billion over 2006.[2] Diabetes costs are now approaching those of cancer.

In an earlier post, I discussed the dramatically protective affect of vitamin D against the development of type-one diabetes (T1). Now we have a new study pointing to the fact that the epidemic of type-two diabetes (T2) is due in part to vitamin D deficiency. Researchers show that insulin sensitivity (necessary to prevent T2) is profoundly improved by vitamin D[3] supplementation. This is the second double-blind, interventional study (“gold-standard” research) to indicate that the risk of T2 is impressively reduced by supplementation. It confirms earlier observational studies, as discussed in my book.

An earlier study of adults with impaired sugar tolerance and insulin resistance (both risk factors for T2) came to even more impressive conclusions. For three years, half the group received a placebo and the others vitamin D plus calcium. The blood-sugar rise was fifteen-times higher in the placebo group, and the increase in insulin resistance was eighteen-times higher.[4]

The answer to T2 prevention: reduce junk-food consumption and achieve optimal levels of vitamin D (60 ng/ml). How? By non-burning sunlight exposure in summer and non-burning tanning bed exposure or supplements in the winter.

[1] Mokad, A. et al. The continuing epidemics of obesity and diabetes in the United States. JAMA 2001; 286:1195-1200.
[2] American Diabetes Association news release, January 2008
[3] Nagpal, J. et al. A double-blind, randomized, placebo-controlled trial of the short-term effect of vitamin D3 supplementation on insulin sensitivity in apparently healthy, middle-aged, centrally obese men. Diabet Med. 2009;261:19-27
[4] Pittas, A. et al. The effects of calcium and vitamin D supplementation on blood glucose and markers of inflammation in nondiabetic adults. Diabetes Care 2007;30:980-86.