HealthNotes

• By Suzanne Dixon, MPH, MS, RD

Can Vitamin D Deflect Diabetes?

Vitamin D is the only vitamin our bodies can make—when our skin is exposed to sunlight of sufficient strength—and it plays many roles in bodily functions, from hormone to cell growth regulator. Now health experts have uncovered evidence of another important task vitamin D may perform: diabetes prevention.

Keeping blood vitamin D levels in the normal range—between 30 and 74 ng/mL—may help reduce your risk

Examining D, tracking diabetes

To examine potential connections between vitamin D and the risk of developing type 2 diabetes, researchers collected blood samples from 961 adult volunteers and analyzed them for vitamin D (25-hydroxyvitamin D) levels. Study participants completed oral glucose tolerance tests and had blood levels of hemoglobin A1c measured multiple times during follow up; both of these tests can be used to diagnose diabetes.

After five years, the study authors noted that:

• 26 of the study participants were newly diagnosed with diabetes.
• People with low vitamin D blood levels were 2.6 times more likely to develop diabetes than people with higher D levels.
• People with high vitamin D blood levels were 83% less likely to develop diabetes than people with low levels.
• Study participant with a vitamin D level considered necessary for optimal health by many health experts—at least 30 nanograms per milliliter (ng/ml)—did not develop diabetes.

Dodging diabetes

This study suggests that keeping blood vitamin D levels in the normal range—between 30 and 74 ng/mL—may help reduce your risk of developing diabetes. However, this type of study is observational, and cannot prove cause and effect. Further, the number of people who ultimately developed type 2 diabetes in this study was small, which makes it harder to know for certain that these two factors are truly connected to one another.

Even so, the results suggest that vitamin D may be an important part of a diabetes prevention plan. Use our tips to help keep type 2 diabetes at bay.

• Stay normal. Normal vitamin D levels fall between 30 and 74 ng/ml; if your levels already are above 30 ng/ml, you likely do not need vitamin D supplements, or more supplements than you currently use.
• Supplement wisely. If your vitamin D levels are below 30 ng/ml—the low end of normal—ask your healthcare provider how much vitamin D you should take and when to get blood levels retested, to make sure the supplements are having the intended effect.
• Go low. If you don’t want, or don’t have a way, to check your vitamin D levels, but are concerned you may not be getting enough D, a low-dose supplement can be your insurance policy; according the health experts, a 600 to 1,200 IU daily vitamin D supplement is safe for nearly everyone.
• Watch weight. The top risk factor for type 2 diabetes is being overweight. If this condition runs in your family, it is especially important to keep off excess pounds.
• Move more. Exercise reduces type 2 diabetes risk, and if you are overweight, even if you don’t lose a single pound, the simple act of moving your body will improve blood glucose control. A 30-minute daily walk is enough to provide health benefits.

(Clin Nutr 2012, In press; doi:10.1016/j.clnu.2011.12.001)