This content originally appeared on Everyday Health. Republished with permission.
By Lisa Rapaport
A daily cup of dark tea may make it easier to maintain healthy blood sugar levels and reduce the risk of developing diabetes, a new study suggests.
For the study, researchers examined data on diabetes diagnoses, blood sugar levels, and lab tests showing how well the body can process sugars for 1,923 adults in China who either didn’t drink tea at all, or who exclusively consumed one type of tea such as green tea, black tea, or a beverage known as dark tea — which, unlike other types of tea, undergoes microbial fermentation during processing.
Overall, people who drank tea daily were 28 percent less likely to have diabetes than participants who didn’t drink tea at all, according to study findings presented at the European Association for the Study of Diabetes (EASD) Annual Meeting in Hamburg, Germany. Daily tea drinkers were also 15 percent less likely to have prediabetes, a condition that develops when blood sugar levels are slightly elevated but not high enough for a full-blown diabetes diagnosis.
Which Kind of Tea Is Best for Diabetes Prevention?
When scientists looked specifically at what type of tea people drank, they found dark tea had the biggest impact on diabetes risk, reducing the odds of this condition by 47 percent and cutting the chances of prediabetes by 53 percent.
“Habitual tea consumption, particularly dark tea, was associated with increased urinary glucose excretion and reduced insulin resistance,” says study co-author Tongzhi Wu, MD, PhD, an associate professor at Adelaide Medical School in Australia.
“These actions are beneficial for glycemic control, and may have contributed to reduced risk of prediabetes and diabetes in the dark tea drinkers,” Dr. Wu adds.
Why Might Tea Help Prevent Diabetes?
When people excrete more glucose, or sugars, in their urine, it can be one indication that their body does a good job of maintaining healthy blood sugar levels, Wu says. Urinary glucose excretion was significantly better in daily tea drinkers than people who didn’t drink tea at all, and better still for people who consumed dark tea.
By contrast, insulin resistance, or an inability to use the hormone insulin to convert sugars into energy, can indicate the body is struggling to manage blood sugar effectively. Drinking any type of tea was associated with a lower risk of insulin resistance, while the risk was reduced further with daily consumption — and even moreso with dark tea.
The study wasn’t a controlled experiment designed to prove whether or how drinking tea in general or dark tea in particular might directly influence blood sugar levels or diabetes risk. It’s also unclear if results from a population in China, where tea consumption is commonplace, might apply to people from other countries where tea isn’t as popular or individuals from other racial or ethnic groups.
Even so, the study adds to an already large body of evidence linking tea consumption, including dark tea, to a lower risk of type 2 diabetes, says Erin Palinski-Wade, RD, CDCES, a nutritionist who works with diabetes patients, who wasn’t involved in the new study.
Many teas are rich in antioxidants that can help reduce inflammation, a condition that’s linked to the development of type 2 diabetes, Palinski-Wade says. Results from the new study and other research point to health benefits from a variety of teas including green tea and black tea in addition to dark tea, Palinski-Wade says. “This is especially true when [unsweetened] tea replaces sugar-rich beverages such as sodas and flavored coffee drinks.”