• Posted October 3, 2023

Tea Drinkers May Gain Better Blood Sugar Control

Drinking dark tea daily may help balance blood sugar levels and stave off type 2 diabetes, the form of the disease most closely tied to obesity.

This is the main message from a new study that looked at tea-drinking habits and diabetes risk among people in China.

Folks who drank dark tea every day had a 53% lower risk of developing prediabetes and a 47% reduced risk for type 2 diabetes when compared to people who never drank tea. Prediabetes refers to blood sugar levels that are higher than normal, but not high enough to be called diabetes yet.

Dark tea is an aged tea from China that has gone through an extensive fermentation process and is rich in healthy bacteria or probiotics that may improve gut health.

The new study wasn't designed to say how, or even if, drinking dark tea improves blood sugar control, but researchers do have some theories. “Tea has been reported to exert numerous desirable effects, which help to reduce inflammation and [damaging] oxidation and improve insulin sensitivity,” said study author Dr. Tongzhi Wu, an associate professor at the Adelaide Medical School in Australia.

For the study, researchers asked 1,923 adults aged 20 to 80 living in China how often they drank tea and what type of tea they preferred whether green, black, dark or another type. The investigators then compared the frequency and type of tea with levels of blood sugar or glucose in the urine, insulin resistance and glycemic status.

In total, 436 people had diabetes and 352 had prediabetes, while 1,135 had normal blood sugar levels. The researchers then compared the frequency and type of tea with levels of blood sugar or glucose in the urine, insulin resistance and glycemic status.

Overall, people who drank tea daily had a 15% lower risk for prediabetes and a 28% reduced risk for type 2 diabetes, compared with those who never drank tea. These benefits were even more pronounced among folks who drank dark tea daily.

“Our study showed for the first time that [drinking tea] is associated with increased urinary glucose excretion, which may also contribute to its blood sugar benefits,” Wu said.

People with diabetes don't get rid of excess glucose in their urine, so blood sugar levels can rise, but regular dark tea drinkers seem to instead have significant increases in the amount of blood sugar in their urine.

Drinking tea also improved insulin resistance. People with diabetes don't produce insulin or are resistant to its effects, and insulin is needed to regulate blood glucose levels.

“As a safe and inexpensive dietary approach, individuals at risk of type 2 diabetes should in general be encouraged to drink tea,” Wu said.

This finding held even after researchers controlled for known diabetes risk factors, including age, ethnicity, weight, smoking status, family history of diabetes and regular exercise.

But Wu cautioned that more studies are needed before drawing any conclusions about how or if dark tea affects diabetes risk. The researchers are now conducting a study looking at the benefits of dark tea on blood sugar control in folks with type 2 diabetes.

The findings were presented Monday at the European Association for the Study of Diabetes (EASD) annual meeting in Hamburg, Germany. Findings presented at medical meetings should be considered preliminary until they are published in a peer-reviewed journal.

Edwin Torres is a nurse practitioner who specializes in diabetes care at the Fleischer Institute for Diabetes and Metabolism at Montefiore Medical Center in New York City.

“The main takeaway from this research is that in Chinese community-dwelling adults, regular tea consumption, especially dark tea, is associated with several positive health outcomes,” said Torres.

The study does have its fair share of limitations, including the fact that it only captured data at a single point in time and the information on tea consumption was self-reported. People don't always accurately recall or report on habits.

In addition, the findings may not necessarily apply to other populations with different dietary habits, genetics and lifestyles, Torres said.

Still, there's lots you can do to lower your risk for type 2 diabetes.

“Individuals at risk for type 2 diabetes can mitigate their risk through lifestyle changes, regular monitoring of blood sugar levels, stress management, adequate sleep, avoidance of tobacco and excessive alcohol, consideration of medication or medical intervention when advised, ongoing education and support, vaccinations, regular eye and foot exams, and maintaining awareness of early symptoms,” he said. “An ounce of prevention is worth more than a pound of treatment.”

More information

HealthDay has more on prediabetes.

SOURCES: Tongzhi Wu, MD, PhD, associate professor, Adelaide Medical School, Australia; Edwin Torres, PhD, nurse practitioner, Fleischer Institute for Diabetes and Metabolism, Montefiore Medical Center, New York City; European Association for the Study of Diabetes (EASD) annual meeting, Hamburg, Germany, Oct. 2 to 6, 2023