More trials needed to assess vitamin D supplements

A report published in the European Journal of Endocrinology looked at study results from a trial involving 96 patients with high risk of diabetes, or who had early diabetes but were not taking diabetes medication, who were randomly assigned to receive either 5,000 IU of vitamin D3 daily or placebo for six months. Over that period, patients newly diagnosed with or at high risk of type 2 diabetes mellitus given vitamin D supplementation showed increased peripheral insulin sensitivity versus placebo. Peripheral insulin sensitivity was measured at baseline and six months using a two-hour hyperinsulinaemic-euglycemic clamp and expressed as an M-value. While the M-value remained constant in the control group during the six month period, it increased by a mean of 23% in the intervention group, indicating increased insulin sensitivity, which has left the researchers to conclude in their paper that larger and longer term randomised controlled trials are necessary.
The researchers said in the report that low vitamin D status is associated with an increased risk of developing diabetes, but randomised controlled trials of vitamin D as an intervention to improve insulin sensitivity have provided inconsistent results: “Larger and longer term RCTs are required to evaluate whether subgroups of patients, including those with low vitamin D status, may benefit from vitamin D supplementation.”