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Recent research indicates that regular consumption of black tea can potentially lower the risk and advancement of type 2 diabetes by enhancing blood sugar regulation. Scientists from the University of Adelaide in Australia and Southeast University in China found that individuals who consumed black tea daily had a 53 percent reduced risk of prediabetes and a 47 percent lower risk of developing Type 2 diabetes. These effects persisted even after accounting for established risk factors like age, gender, ethnicity, body mass index (BMI), average blood pressure, fasting glucose levels, and cholesterol.
Associate Professor Tongzhi Wu, co-author of the study and a Mid-Career Fellow at The Hospital Research Foundation Group, remarked, “The significant 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.” He further explained, “Our findings suggest that habitual tea consumption may protect against blood sugar spikes by increasing glucose excretion in urine, enhancing insulin resistance, and thereby achieving better blood sugar control. These advantages were most pronounced among those who consumed dark tea daily.”
The favorable impact on metabolic control may be attributed to the distinctive fermentation process involved in dark tea production. This process may yield unique bioactive compounds (such as alkaloids, free amino acids, polyphenols, polysaccharides, and their derivatives) that exhibit powerful antioxidant and anti-inflammatory effects, improve insulin sensitivity, enhance the function of pancreatic beta cells, and alter the composition of gut bacteria.
This recent cross-sectional study encompassed 1,923 adults (562 men, 1,361 women aged 20-80 years) residing in various provinces across China. Among them, 436 participants had diabetes, 352 had prediabetes, and 1,135 had normal blood glucose levels. The participants comprised both non-regular tea drinkers and those with a history of exclusively consuming a single type of tea. They were queried about the frequency (i.e., never, occasionally, often, and daily) and type (i.e., green, black, dark, or other) of tea consumption.
The researchers scrutinized the correlation between both the frequency and type of tea consumption and the excretion of glucose in urine (measured by the morning spot urine glucose-to-creatine ratio [UGCR]), insulin resistance (assessed using the triglyceride and glucose index [TyG] derived from fasting plasma glucose and fasting triglyceride levels), and glycemic status (defined as a history of type 2 diabetes, current use of antidiabetic medications, or an abnormal 75g oral glucose tolerance test).
Individuals with diabetes often exhibit an elevated capacity for renal glucose reabsorption, causing their kidneys to retain more glucose, preventing its excretion in urine, and contributing to elevated blood sugar levels.
According to Associate Professor Wu, “These findings suggest that bioactive compounds in dark tea may directly or indirectly influence glucose excretion in the kidneys, to some extent resembling the action of sodium-glucose cotransporter-2 (SGLT2) inhibitors, a new class of anti-diabetic drugs known for their effectiveness in preventing and treating type 2 diabetes, as well as their substantial protective effects on the heart and kidneys.”
Co-lead author Professor Zilin Sun from Southeast University added, “Our findings indicate that daily consumption of dark tea has the potential to reduce the risk and progression of type 2 diabetes through improved blood sugar control. When considering all the various biomarkers associated with habitual consumption of dark tea, it might be one simple step people can easily take to enhance their diet and overall health.”
