For many of us, a swig of mouthwash twice per day forms a part of our oral hygiene routine. But according to new research, this seemingly beneficial practice may pose a surprising health risk: mouthwash use could increase the risk of diabetes.

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Researchers suggest that frequent mouthwash use could increase the risk of diabetes.

Researchers suggest that using mouthwash at least twice every day destroys “friendly” oral bacteria, which can, in turn, alter blood sugar metabolism and promote diabetes, particularly for people who are already at high risk for the condition.

Study co-author Rakesh P. Patel — from the Department of Pathology and Center for Free Radical Biology in the University of Alabama at Birmingham — and colleagues have published their findings in the journal Nitric Oxide.

It is estimated that around 30.3 million people in the United States have diabetes, which is a condition characterized by high blood glucose levels.

A further 84.1 million adults in the U.S. have prediabetes, wherein blood glucose levels are higher than normal but are not high enough to warrant a diabetes diagnosis.

Being overweight is one of the biggest risk factors for diabetes. According to the new study, the simple practice of using mouthwash could exacerbate this risk.

The scientists came to their intriguing findings by analyzing the data of 1,206 overweight or obese adults aged 40–65. All adults were part of the San Juan Overweight Adults Longitudinal Study, and they were free of diabetes and major cardiovascular diseases at study baseline.

As part of the study, participants were asked how often they used mouthwash. A total of 43 percent of the subjects said that they used mouthwash at least once daily, while 22 percent said that they used it at least twice daily.

Over an average of 3 years of follow-up, the team monitored the development of prediabetes or diabetes among the participants. A total of 945 subjects were included in the final analysis.

Compared with participants who did not use mouthwash, those who reported using mouthwash at least twice daily were 55 percent more likely to develop prediabetes or diabetes over 3 years.

There was no association between using mouthwash less than twice per day and the risk of prediabetes or diabetes, the researchers report.

These findings persisted after accounting for a number of possible confounding factors, including diet, oral hygiene, sleep disorders, medication use, fasting glucose levels, income, and education levels.

Commenting on their findings, Patel and colleagues write:

Frequent regular use of over-the-counter mouthwash was associated with increased risk of developing prediabetes/diabetes in this population.”

Many mouthwashes contains antibacterial compounds — such as chlorhexidine — that kill bacteria in order to help prevent gingivitis, tooth decay, and other oral health conditions.

Patel and colleagues suspect that these compounds also destroy “good” bacteria in the mouth that are important for the formation of nitric oxide, which is a chemical compound that helps to regulate insulin — the hormone that controls blood sugar levels.

Therefore, the destruction of this beneficial bacteria could encourage the development of diabetes.

Given that more than 200 million people in the U.S. use mouthwash, these latest findings could be a cause for concern. However, it is important to note that the study is purely observational.

Patel and colleagues say that further research is needed to determine whether a seemingly innocent oral hygiene product is really a risk factor for diabetes.