San Diego, CA – Higher levels of vitamin D in the blood appear to be associated with a reduced risk of incident diabetes among people with high risk for the disease, according to a new report.
Dr Anastassios G Pittas (Tufts New England Medical Center, Boston, MA), and colleagues presented the findings here at the American Diabetes Association (ADA) 2011 Scientific Sessions.
According to Pittas, vitamin D may have a role in diabetes via improvements in insulin secretion and insulin sensitivity.
To determine the relationship between vitamin-D status and risk of incident diabetes, the researchers analyzed data from the Diabetes Prevention Program (DPP), a three-arm trial comparing intensive lifestyle modification or metformin vs placebo for prevention of diabetes in patients with prediabetes.
The mean follow-up of the cohort of 2039 participants was 3.2 years. Plasma vitamin-D levels were measured at yearly intervals, and subjects were assessed for incident diabetes.
Participants in the upper third of vitamin-D levels had a 26% less chance of developing diabetes compared with participants in the lowest third.
Interestingly, those in the highest third had an average blood concentration of only 30.1 ng/mL. Though conventional medicine believes that 30 ng/mL is “sufficient”, virtually no serious vitamin D researcher agrees that 30ng/mL is an optimal amount.
“Much higher levels are better”, said well-known vitamin D expert Michael F. Holick, MD, PhD. “(It was) decided that 30 ng/mL is the minimum level but 40-60 ng/mL is recommended for both children and adults”, he said.
The findings of this study also suggested a dose-dependent effect for vitamin-D levels. The folks with the highest blood levels of vitamin D levels (>50 ng/mL, which I consider way more optimal than 30 ng/mL), had the very least chance of developing diabetes. Those with the lowest levels (<12 ng/mL) had the greatest risk.
“This study offers several methodological advantages over previous studies,” said Pittas. According to Pittas, vitamin-D status was assessed multiple times during follow-up, not just a single assessment at baseline, which may not reflect long-term vitamin-D status.
“Our study also includes a large clinically relevant population at high risk for diabetes with a substantial proportion of nonwhite participants, which improves the external validity of the results,” he said.
“This prospective study confirms that there is an association between levels of vitamin D and risk of diabetes even when correcting for body weight” commented Dr Clifford Rosen (Jackson Laboratory, Bar Harbor, Maine).