A high dose of vitamin D could improve the function of insulin-producing beta cells in children and young adults recently diagnosed with Type 1 diabetes.

The discovery, published in JAMA Network Open, could mean that a more cost-effective way of managing the disease affecting 1.45 million Americans has been on pharmacy shelves all along.

“Type 1 diabetes affects millions of people and treatment options can often be costly,” Dr. Benjamin Nwosu, chief of endocrinology and director of the diabetes center at Cohen Children’s Medical Center and the principal author of the research paper, said in a press release. “It is exciting to know that vitamin D could protect the beta cells of the pancreas and increase the natural production of good and functional insulin in these patients.”

People with Type 1 diabetes do not make enough insulin, the hormone responsible for producing and moving blood sugar into the body’s cells for energy. Without enough insulin, blood sugar can’t get into the cells and stays trapped in the bloodstream, which causes diabetes symptoms. Complications of Type 1 diabetes include heart disease, stroke, circulatory problems, eye issues, nerve damage, kidney disease, and gum disease.

How Vitamin D Helps Manage Type 1 Diabetes

Dr. Nwosu and his team uncovered vitamin D’s effects on diabetes by conducting a 12-month trial with 36 youths between the ages of 10 and 21. The average age of the participants was 13. Most of the participants were boys (24).

During the trial, Dr. Nwosu and his team randomly provided the participants with either a dose of ergocalciferol—a form of vitamin D, also known as vitamin D2—or a placebo. The research team found that taking the vitamin D supplement helped the body reduce the proinsulin to C-peptide ratio and delayed the loss of C-peptide more than the placebo. When C-peptide is present, the body is still producing insulin; in other words, the young people’s bodies made insulin that worked the way it was supposed to work.

Dr. Nwosu said slowing down C-peptide loss and improving the function of insulin-producing cells could extend the “honeymoon phase” of Type 1 diabetes.

The “honeymoon phase” is the critical time of Type 1 diabetes when treatment options determine the long-term outlook of the disease, especially for a young person. Typically, after the honeymoon phase, beta cells, which are located in the pancreas, retain between 3o percent and 50 percent of their function, according to Dr. Nwosu’s research. The beta cells can continue to produce insulin for years after the initial diagnosis, which is why prolonging the partial remission phase can help reduce long-term complications of the disease.

Vitamin D Could Benefit Type 1 Diabetics, but More Treatment Needed

The discovery builds upon Dr. Nwosu’s previous work, which showed that high doses of vitamin D are safe and effective in improving glucose control. Dr. Nwosu’s research has also shown that vitamin D prolongs the remission phase of Type 1 diabetes in children and adolescents.

Dr. Nwosu and his team noted that while vitamin D supplementation could elongate the honeymoon phase, more treatment options are likely necessary for those managing Type 1 diabetes.

“Repurposing commonly used supplements such as vitamin D, which is known to be safe and effective for other ailments, presents an opportunity to continue developing other therapies needed to treat type 1 diabetes,” Dr. Charles Shleien, senior vice president and chair of pediatric services at Northwell Health, said in the press release.

Vitamin D is a readily available supplement that comes in several forms. Ergocalciferol, or vitamin D2, is particularly common and has little to no side effects. Too much vitamin D could cause high calcium levels, which can lead to nausea, vomiting, constipation, unusual tiredness, and potential mental or mood changes, but this only happens with extremely high levels of vitamin D of about 10,000 international units (IUs) per day for an extended period.

Individuals with Type 1 diabetes or prediabetes need to connect with their physician or health care provider before beginning any new type of medication or supplement.