Diabetes mellitus type I
Studies in mice have suggested that pretreating mice that are prone to developing type I diabetes with the active form of vitamin D (1,25-hydroxyvitamin D [1,25(OH)2D]) reduces the development of type I diabetes by 80%. This study is supported by the observation in Finland where children in the 1960’s routinely received 2,000 IU of vitamin D a day during their first year of life. When these children were followed for the next 31 years, it was observed that these children had a reduced risk of developing type I diabetes by 78%. Children who were vitamin D deficient at the same time and also followed for 31 years had an almost 300% increased risk of developing type I diabetes.
Hypponen E, Laara E, Jarvelin M-R, Virtanen SM. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet 2001;358:1500-1503.
Diabetes mellitus type II
The beta islet cells that produce insulin in the pancreas have a vitamin D receptor. The active form of vitamin D stimulates the pancreas to produce insulin. It has been observed that the relative risk of developing type II diabetes is reduced by as much as 33% in men and women who increase their intake of vitamin D above 800 IU/day along with 1,000 milligrams of calcium.
Pittas AG, Dawson-Hughes B, Li T, et al. Vitamin D and calcium intake in relation to type 2 diabetes in women. Diabetes Care 2006:29:650-56.