Tea is touted for its health benefits, including its ability to fight inflammation, boost immunity and provide protection against various forms of cancer. Researchers now say regular drinking of dark tea can slash the risk of developing diabetes to almost half.

Daily consumers of dark tea are at a 53% lower risk of developing prediabetes and 47% reduced risk for type 2 diabetes compared to people who never drink tea, a new study suggests. The findings of the study were presented at the annual meeting of the European Association for the Study of Diabetes (EASD) in Hamburg, Germany.

Type-2 diabetes occurs when cells develop insulin resistance, a condition in which they do not respond normally to insulin, the hormone produced by the pancreas for blood sugar regulation.

Prediabetes is a health condition wherein the blood sugar levels are high but not high enough to be considered diabetic. More than 30% of adults in the U.S. are prediabetic. A person is considered diabetic when the fasting blood sugar level is 126 mg/dL or higher in two separate tests, while they are prediabetic when the fasting level is from 100 to 125 mg/dL.

"The substantial health benefits of tea, including a reduced risk of cardiovascular disease and type 2 diabetes, have been reported in several studies over recent years, but the mechanisms underlying these benefits have been unclear," study co-lead author Tongzhi Wu, from the University of Adelaide, Australia, said in a news release.

Researchers attribute the protective effects on blood sugar management to increased glucose excretion and improved insulin resistance that comes with habitual tea drinking. The observational study does not prove that drinking tea every day improves blood sugar control but suggests it can likely contribute to better sugar control.

"Our findings hint at the protective effects of habitual tea drinking on blood sugar management via increased glucose excretion in urine, improved insulin resistance and thus better control of blood sugar. These benefits were most pronounced among daily dark tea drinkers," Wu said.

The secret to better metabolic control lies in the microbial fermentation of dark tea. The process brings out bioactive compounds with antioxidant and inflammatory effects, which improve insulin sensitivity, better performance of pancreatic beta cells and change the composition of the gut bacteria, the researchers said.

The study included 1,923 adults from eight provinces in China. Of them, 436 participants had diabetes, 352 were prediabetic, and the rest had normal blood glucose levels. The study examined the frequency and the type of tea consumed by the participants.

Researchers measured the consumption and excretion of glucose in the urine, insulin resistance, and glycemic status (blood glucose level) of the participants.

Diabetes patients tend to reabsorb glucose, which contributes to higher blood sugar levels.

"After accounting for differences in age, sex, and clinical and lifestyle factors, the analysis found that drinking tea every day was associated with an increase in urinary glucose excretion (UGCR by 0.11 mmol/mmol) and a reduction in insulin resistance (TyG by -0.23), as well as 15% lower risk for prediabetes and 28% reduced risk for type 2 diabetes, compared with never tea-drinkers," the researchers wrote.

To further validate the findings, researchers conducted a double-blind, randomized trial on people living with type 2 diabetes.

"Our findings suggest that drinking dark tea every day has the potential to lessen type 2 diabetes risk and progression through better blood sugar control. When you look at all the different biomarkers associated with habitual drinking of dark tea, it may be one simple step people can easily take to improve their diet and health," added co-lead author Zilin Sun, from Southeast University.

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