Raising low vitamin D levels lowers risk of prediabetes progressing to diabetes
Vitamin D and calcium supplementation along with diet and exercise may prevent type 2 diabetes in prediabetic individuals who have insufficient vitamin D in their bodies, a study from India suggests. The results were presented Saturday at the joint meeting of the International Society of Endocrinology and the Endocrine Society: ICE/ENDO 2014 in Chicago.
Vitamin D deficiency has been linked to prediabetes, which is a blood glucose, or sugar, level that is too high but not high enough to be considered diabetes. It is unclear, however, if bringing low vitamin D blood levels to normal through supplementation will affect progression to diabetes.
In the new study, every unit increase in vitamin D level after supplementation of the vitamin decreased the risk of progression to diabetes by 8 percent, the authors reported.
"Without healthy lifestyle changes, nothing works to prevent diabetes in at-risk individuals," said the lead author, Deep Dutta, MD, DM, a research officer at the Institute of Postgraduate Medical Education & Research and Seth Sukhlal Karnani Memorial Hospital in Calcutta, India. "However, our results are encouraging because the addition of vitamin D and calcium supplements is easy and low in cost."
"If our results are confirmed in a large multicenter trial," Dutta said, "vitamin D supplementation would provide us with a new tool in the armamentarium of diabetes prevention strategies."
The West Bengal chapter of the Research Society for the Study of Diabetes in India funded this study. Of 170 individuals with prediabetes who had not taken vitamin D supplements in the past six months, 125 had vitamin D deficiency or insufficiency, which the researchers defined as a vitamin D blood level (25-hydroxyvitamin D) of 30 nanograms per milliliter (ng/mL) or less. These 125 study subjects were randomly assigned to one of two treatment groups. In the first group, 68 subjects received ready-to-mix, powdered vitamin D3 (cholecalciferol, D-Rise sachets, USV Ltd., Mumbai, India) at a dose of 60,000 International Units (IU) once weekly for eight weeks and then monthly. They also received a daily 1,250-milligram calcium carbonate tablet.
The other group of 57 subjects received only calcium supplements. Both groups received advice to eat a healthy, calorie-appropriate diet and to engage in brisk exercise for 30 minutes each day.
The researchers analyzed results for subjects who had at least a year of follow-up tests. After an average of nearly two years and four months' follow-up, only six of 55 subjects (10.9 percent) in the group that received vitamin D plus calcium supplementation had become diabetic, whereas diabetes developed in 13 of 49 individuals (26.5 percent) in the calcium-alone group. Blood sugar levels reportedly became normal in about twice as many people in the vitamin D group as in the group that did not get vitamin D supplementation: 23 of 55 subjects versus 10 of 49 subjects, respectively (41.8 percent versus 20.4 percent).
At the end of the study, those who received vitamin D supplementation had much higher vitamin D levels in the blood and lower fasting blood glucose levels compared with the other group. Every unit (1 ng/mL) increase in vitamin D in the body was associated with a 5.4 percent increased chance of reversal to normal blood sugar levels, Dutta reported.
He said the greater reversal to normal blood sugar in the vitamin D group presumably occurred through improvements in their insulin resistance and inflammation.
Vitamin D Could Lower Risk of Developing Diabetes
Scientists at the Helmholtz Zentrum München have shown that people with a good vitamin D supply are at lower risk of developing Type 2 diabetes mellitus. The study, which was conducted in cooperation with the German Diabetes Center and the University of Ulm, was published in the scientific journal Diabetes Care.
New tests performed on participants of the KORA study have shown that people with a good supply of vitamin D have a lower risk of developing Type 2 diabetes mellitus, while individuals with lower concentrations of vitamin D in their blood have a higher risk. This effect could be attributable, amongst other things, to the anti-inflammatory effect of vitamin D. The result of the study, which was conducted at the Helmholtz Zentrum München in cooperation with Dr. Christian Herder of the German Diabetes Center in Düsseldorf and Dr. Wolfgang König, Professor of Medicine/Cardiology at the University of Ulm, could have direct consequences for the prevention of this common disease.
"Vitamin D deficiency is relatively widespread due to our modern way of life and the geographical latitude of Germany. In the winter months, in particular, people often do not receive adequate supplies of the vitamin because of the lack of sunlight," explains Dr. Barbara Thorand of the Institute for Epidemiology II at the Helmholtz Zentrum München. "If follow-up studies confirm our results, a targeted improvement in the supply of vitamin D to the general public could at the same time reduce the risk of developing diabetes." The human body can produce vitamin D itself if it has sufficient exposure to sunlight. The UVB radiation in natural daylight splits the precursor of vitamin D, 7-dehydrocholesterol, in the skin and forms provitamin D3. Further vitamin D synthesis occurs in the liver and kidneys. In addition, the supply can be improved by eating specific foods, such as oily fish, eggs and milk products, or by taking vitamin D supplements.
Low vitamin D levels may increase risk of Type 1 diabetes
Having adequate levels of vitamin D during young adulthood may reduce the risk of adult-onset type 1 diabetes by as much as 50%, according to researchers at Harvard School of Public Health (HSPH). The findings, if confirmed in future studies, could lead to a role for vitamin D supplementation in preventing this serious autoimmune disease in adults. The study was published in the March 1 2013 print edition of the American Journal of Epidemiology.
"It is surprising that a serious disease such as type 1 diabetes could perhaps be prevented by a simple and safe intervention," said lead author Kassandra Munger, research associate in the Department of Nutrition at HSPH.
This study provides the strongest findings to date to suggest that vitamin D may be protective against type 1 diabetes.
In type 1 diabetes (once called juvenile-onset or insulin-dependent diabetes), the body's immune system attacks and permanently disables the insulin-making cells in the pancreas. About 5% of the estimated 25.8 million people in the United States with diabetes have type 1, according to the American Diabetes Association. Although it often starts in childhood, about 60% of type 1 diabetes cases occur after age 20.
Previous studies have suggested that a shortage of vitamin D might boost type 1 diabetes risk, although those studies mostly examined the link between vitamin D levels in pregnancy or childhood and the risk of type 1 diabetes in children. Other research, in young adults, uncovered an association between high vitamin D levels and a lowered risk of multiple sclerosis—an autoimmune disease genetically and epidemiologically related to type 1 diabetes—suggesting that inadequate vitamin D in adulthood may be an important risk factor for autoimmune diseases in general.
Long-term study of military personnel
The researchers conducted a prospective case-control study of U.S. military personnel on active duty, using blood samples from the Department of Defense Serum Repository, which contains more than 40 million samples collected from 8 million military personnel since the mid-1980s. Identifying 310 individuals diagnosed with type 1 diabetes between 1997 and 2009, the team examined blood samples taken before onset of the disease, and compared the samples with those of 613 people in a control group.
The researchers found that white, non-Hispanic, healthy young adults with higher serum levels (>75 nmol/L) of vitamin D had about half the risk of developing type 1 diabetes than those with the lowest levels of vitamin D (<75 although="" among="" and="" association="" authors="" be="" blacks="" due="" found="" groups.="" hispanics="" in="" individuals="" may="" nmol="" no="" number="" of="" researchers="" said="" significant="" small="" span="" the="" these="" this="" to="">75>
"The risk of type 1 diabetes appears to be increased even at vitamin D levels that are commonly regarded as normal, suggesting that a substantial proportion of the population could benefit from increased vitamin D intake," said Alberto Ascherio, professor of epidemiology and nutrition at HSPH, the study's senior author.
About vitamin D
Worldwide, an estimated 1 billion people have inadequate levels of vitamin D in their blood, and deficiencies can be found in all ethnicities and age groups. While sun exposure is an excellent source of vitamin D, sunscreen, clothing, skin pigmentation, and winter months reduce vitamin D production. Food tends to be a poor source of vitamin D, with "good" sources, such as salmon and fortified milk, containing 400IU or less per serving. "Whereas it is premature to recommend universal use of vitamin D supplements for prevention of type 1 diabetes, the possibility that many cases could be prevented by supplementation with 1,000-4,000 IU/day, which is largely considered safe, is enticing," the authors said.