Having a daily cup of tea can slash risk of developing type 2 diabetes

By Jim Leffman via SWNS

A daily cup of tea can slash the risk of developing type 2 diabetes by more than a quarter, a new study shows.

Compared to people who don't drink tea, those who did reduce their chances of becoming a type 2 diabetic by at least 28 percent.

It also reduced the risk of developing prediabetes by 15 percent.

The hot beverage increases glucose excretion in urine, improving insulin resistance and therefore better control of blood sugar.

One in every 16 people in the UK has diabetes, the majority with type 2, caused by unhealthy lifestyles.

The researchers, from the University of Adelaide in Australia and Southeast University in China, found that dark tea, a specific type not widely available in the UK, reduced the risk by nearly half (47 percent).

The study, reported in the journal Diabetologia, was presented at the Annual Meeting of The European Association for the Study of Diabetes (EASD) in Hamburg.

The team found that the beneficial effects on metabolic control may lie in the unique way dark tea is produced.

This involves microbial fermentation, a process that may yield unique bioactive compounds including alkaloids, free amino acids, polyphenols, polysaccharides, and their derivatives.

These all exhibit potent antioxidant and anti-inflammatory effects, improve both insulin sensitivity and the performance of beta cells in the pancreas, and change the composition of the bacteria in the gut.

But the effects are also present to a lesser extent in other teas.

The study included 1,923 adults (562 men,1,361 women aged 20-80 years) living in the community across eight provinces in China.

In total, 436 participants were living with diabetes and 352 with prediabetes, and 1,135 had normal blood glucose levels.

Associate Professor Tongzhi Wu from Adelaide University said "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.

“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.”

He added: "Indeed, there are quite some confusions about the differences between black tea and dark tea, particularly from the Western consumers’ point of view.

"The classification of tea in Asia (China) is based on the respective processing method.

"For example, green does not involve fermentation. A distinct feature of dark tea, relative to other tea (black tea), is the involvement of microbial organisms in the fermentation process."

Those drinking dark tea also had a 53 percent reduced risk of prediabetes. The team took into account established risk factors known to drive the risk for diabetes, including age, gender, ethnicity, body mass index (BMI), average arterial blood pressure, fasting plasma glucose, cholesterol, alcohol intake, smoking status, family history of diabetes and regular exercise.

Participants included both non-habitual tea drinkers and those with a history of drinking only a single type of tea.

They were asked about the frequency and type of tea consumption.

People with diabetes often have an enhanced capacity for renal glucose reabsorption, so their kidneys retrieve more glucose, preventing it from being excreted in urine, which contributes to higher blood sugar.

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 and a reduction in insulin resistance compared with never-tea-drinkers.

According to Associate Professor Wu: “These findings suggest that the actions of bioactive compounds in dark tea may directly or indirectly modulate glucose excretion in the kidneys, an effect, to some extent, mimicking that of sodium-glucose co-transporter-2 (SGLT2) inhibitors, a new anti-diabetic drug class that is not only effective at preventing and treating type 2 diabetes but also has a substantial protective effect on the heart and kidneys.”

Co-lead author Professor Zilin Sun from Southeast University added: “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.”

Despite the promising findings, the authors caution that as with any observational study, the findings cannot prove that drinking tea every day improves blood sugar control by increasing urinary glucose excretion and reducing insulin resistance, but suggest that they are likely to contribute.

They are currently conducting a double-blind, randomized trial to investigate the benefits of dark tea on blood glucose control in people living with type 2 diabetes to validate their findings.

In addition, they cannot rule out the possibility that residual confounding by other lifestyle and physiological factors may have affected the results.