Green tea may help manage type 2 diabetes in a few key areas, including blood sugar, weight, and inflammation.
Blood Sugar Regulation
Green tea may help regulate blood sugar levels by improving insulin sensitivity, allowing the body to use insulin more effectively. Some experts believe that this may help prevent type 2 diabetes.
Researchers in Japan looked at L-theanine levels and green tea consumption and found that green tea drinkers were significantly less likely to develop type 2 diabetes over seven years.
A study of over half a million people in China found that daily green tea drinking was associated with a lower risk of developing type 2 diabetes and a low risk of premature death from any cause in people who already had diabetes.
Dr. Bruno conducted a trial using green tea extract gummies that included 40 people: 21 with metabolic syndrome and 19 healthy adults. Metabolic syndrome includes several conditions that increase the likelihood of developing heart disease, stroke, and type 2 diabetes. All participants consumed green tea gummies for 28 days. The daily dose was equivalent to five cups of green tea. After a one-month break from consuming any green tea products, the participants were given placebo gummies, also for one month. Researchers found that fasting blood glucose levels for all participants were significantly lower after taking the green tea gummies compared with levels after taking the placebo.
Weight Management
Maintaining a healthy weight can help manage type 2 diabetes, though the evidence on green tea and weight loss is mixed.
Some studies have shown that the polyphenols in green tea — antioxidants that may improve metabolism and reduce fat absorption — can promote weight loss, but other research does not support these results.
A study of over 10,000 middle-aged adults found that women who drank at least four cups of green tea a week were less likely to have abdominal obesity than women who didn’t drink it, though the same benefits weren’t found in their male counterparts.
A review of the effects of green tea supplements on obesity found that there could be some modest improvements in weight or waist circumference in people who took the supplements for three months or longer.
The bottom line, says Dr. Tan, is that the effects of green tea on weight control are not proven, and how it could help shed pounds remains unclear.
Cardiovascular Benefits
People with type 2 diabetes are at a higher risk of cardiovascular disease, including heart disease. Some studies suggest that green tea may offer cardiovascular protection by improving levels of LDL (“bad”) cholesterol as well as total cholesterol.
A meta-analysis of five studies totaling over 600,000 people concluded that those who drank two to four cups of green tea a day lowered their risk of stroke between 21 and 24 percent.
One theory is that the flavonoids in green tea open blood vessels and keep them flexible, helping blood flow more freely.
Green tea is also associated with lowering chronic high blood pressure. A meta-analysis of randomized, placebo-controlled trials found that green tea lowered both systolic and diastolic blood pressure.
Anti-Inflammatory Effects
Chronic inflammation is common in people with type 2 diabetes and is believed to play a role in insulin resistance.
Green tea’s effect on inflammation in the body is less clear than the benefits for weight loss and blood sugar, says Bruno.
“However, it should be noted that inflammation is a complex interplay that involves many aspects of the immune system, and it is difficult to generalize effects regarding inflammation because there are many different inflammatory proteins that, when at appropriate levels, support health and well-being, but when dysregulated — either too high or too low — can be harmful to health. That being said, recent evidence indicates that green tea may reduce specific indicators of gut inflammation,” says Bruno.