Vitamin D May Offset Diabetes Risk While on Antipsychotic Drugs

Atypical antipsychotics, such as the drugs quetiapine (Seroquel) and olanzapine (Zyprexa), are known to carry a heightened risk for the development of new-onset diabetes. Atypical antipsychotics are typically prescribed for severe disorders such as schizophrenia, bipolar disorder, autism, and as an adjunct in major depressive disorder.

However, in a new study, researchers at Kyoto University have discovered that simply taking vitamin D can significantly lower the risk of developing drug-induced diabetes in these patients. Using a data mining method, the researchers have been searching for potential antidotes to side-effects of pre-existing drugs on the U.S. FDA’s Adverse Event Reporting (FAERS) system, which is the largest database of self-reported adverse side effects.

“We found that patients who had coincidentally been prescribed vitamin D with quetiapine were less likely to have hyperglycaemia,” says lead researcher Shuji Kaneko. “It’s unusual for vitamin D to be prescribed with quetiapine because it is typically prescribed to treat osteoporosis; in fact, there were only 1232 cases in the world where vitamin D was prescribed with quetiapine. Data mining proved helpful in locating these cases.”

“Databases like FAERS aren’t just for making drug regulations; they have so much potential for side-effect relief using pre-existing drugs,” says Kaneko. “There’s a lot we can hope for from reverse translational research like this.”

Conventional “typical” antipsychotics have been available since the mid-1950s. In the 1990s, new antipsychotic medications were developed, and these new drugs were referred to as second generation or “atypical” antipsychotics.

While this newer group of antipsychotics are thought to be safer than typical antipsychotics, they still have severe side effects, including significant weight gain, tardive dyskinesia (a serious movement disorder), neuroleptic malignant syndrome, and increased risk of stroke, sudden cardiac death, blood clots, and diabetes.

After discovering that vitamin D helps offset diabetes in patients taking quetiapine, the researchers took it further and confirmed the finding in tests with mice. They found that the mice who were given vitamin D along with quetiapine had significantly lower levels of blood sugar than those that took only quetiapine.

“Interestingly, vitamin D on its own doesn’t lower diabetes risk, but it certainly defends against the insulin-lowering effects of quetiapine,” said lead author Takuya Nagashima. “We clarified the molecular mechanisms of how quetiapine causes hyperglycaemia using datasets in a genomics data repository. Through this we found that quetiapine reduces the amount of a key enzyme called PI3K that gets produced. Vitamin D stops quetiapine from lowering PI3K production.”

The findings are published in the journal Scientific Reports.

Source: Kyoto University