SATURDAY, June 19 (HealthDay News) -- A pair of new studies has uncovered evidence that low levels of vitamin D could lead to poor blood sugar control among diabetics and increase the risk of developing metabolic syndrome among seniors.

Both findings are slated to be presented Saturday at the Endocrine Society's annual meeting in San Diego.

In one study, researchers at the Johns Hopkins University School of Medicine in Baltimore reviewed the medical charts of 124 type 2 diabetes patients who sought specialty care at an endocrine outpatient facility between 2003 and 2008.

More than 90 percent of the patients, who ranged in age from 36 to 89, had either vitamin D deficiency or insufficiency, the authors found, despite the fact that they all had had routine primary care visits before their specialty visit.

Just about 6 percent of the patients were taking a vitamin D supplement at the time of their visit, the research team noted, and those who had lower vitamin D levels were also more likely to have higher average blood sugar levels.

"This finding supports an active role of vitamin D in the development of type 2 diabetes," study co-author Dr. Esther Krug, an assistant professor of medicine, said in a news release from the Endocrine Society.

"Since primary care providers diagnose and treat most patients with type 2 diabetes, screening and vitamin D supplementation as part of routine primary care may improve health outcomes of this highly prevalent condition," Krug added.

A second study involving nearly 1,300 white Dutch men and women over the age of 65 found almost half were vitamin D-deficient, while 37 percent had metabolic syndrome.

Metabolic syndrome is a grouping of health risk factors, including high blood pressure, abdominal obesity, abnormal cholesterol levels and high blood sugar.

"Because the metabolic syndrome increases the risk of diabetes and cardiovascular disease, an adequate vitamin D level in the body might be important in the prevention of these diseases," study co-author Dr. Marelise Eekhoff, of VU University Medical Center in Amsterdam, said in the same news release.

Regardless of gender, those with insufficient amounts of vitamin D in their blood were more likely to have the syndrome than those with sufficient amounts of vitamin D, Eekhoff and her colleagues found.

"It is important," added Eekhoff, "to investigate the exact role of vitamin D in diabetes to find new and maybe easy ways to prevent it and cardiovascular disease."

More information

For more on vitamin D, visit the U.S. National Library of Medicine.