Analyzing the link between vitamin D levels and diabetes over a 12-year period, scientists studied 903 adults who were known to be free of diabetes during a 1997-1999 visit to the NIH Lipid Research Clinic, where vitamin D3 levels were measured. The average age of the participants was 74. Follow up continued through 2009.

In the group studied, there were 47 cases of diabetes and 337 cases of prediabetes. The results were published in the journal PLoS One.

Compared to those with levels of vitamin D3 below 30 ng/mL, subjects with higher vitamin D3 levels had a lower risk of diabetes.

People with vitamin D3 levels of 30-39 ng/mL had a 69 percent lower risk; those with levels of 40-49 ng/dL had a 71 percent lower risk.

The best results were vitamin D3 levels greater than 50 ng/ mL — 81 percent lower risk.

This showed that each 10 ng/mL higher concentration of vitamin D3 was associated with a 36 percent lower risk of diabetes.

Unfortunately, we have more diabetes in our country than we know what to do with, mostly because of eating too many refined foods and a lack of exercise.

This study found a protective effect with maintaining higher vitamin D3 levels. When a study shows a linear response — the higher the level the better the effect — attention should be paid.

The best way to maintain vitamin D3 levels is to expose your skin to sunshine. Taking vitamin D3 supplements appropriately is safe as well.

Generally, I suggest patients supplement with vitamin D3 during the fall and winter months. Doses from 2,000 IU to 6,000 IU per day have proven safe.