The Importance of Choosing Good Drinks for Diabetes
When you have type 2 diabetes, your body’s cells can no longer efficiently absorb blood sugar (glucose), the body's main energy source, due to a condition called insulin resistance. Insulin resistance leads to an elevated blood glucose level (called hyperglycemia), which increases the risk for diabetes complications, including heart disease, kidney failure, and nerve damage (neuropathy).
What you choose to eat and drink can affect your blood sugar level dramatically, the Mayo Clinic points out. The Harvard T.H. Chan School of Public Health notes that one of the main drivers behind the obesity and diabetes epidemic is added sugar — namely, the added sugar in popular sips like sports drinks, soda, and fruit juice. It’s this very aspect of your diet where green tea can be helpful in stabilizing blood sugar.
The Science-Backed Health Benefits of Green Tea for Diabetes
There’s a wealth of research on how green tea may help with weight loss and thus help people with type 2 diabetes get their blood sugar under control. It depends on the variety, but a plain cup of green tea from a steeped bag contains 0 calories. That means it’s a great alternative to sugary and caloric sodas and energy drinks.
“When you lose weight, you increase your insulin sensitivity and will have a lower blood sugar level,” says Sandra Arevalo, MPH, RDN, a certified diabetes educator. A study published in the Journal of Research in Medical Sciences looked at different doses of green tea in 63 people with type 2 diabetes. Researchers found that drinking 4 cups per day was linked to weight loss and lower blood pressure.
Toby Smithson, RDN, CDE, author of Diabetes Meal Planning and Nutrition for Dummies, explains that the catechins in green tea help reduce the effects of insulin resistance by decreasing the digestion and absorption of carbohydrates. (Catechins are a type of antioxidant.) A study published in September 2014 in the Iranian Journal of Medical Sciences suggests that drinking green tea regularly — participants drank a 150-milliliter infusion three times per day for four weeks — had a positive effect on insulin resistance in people with diabetes and increased their HDL ("good") cholesterol levels. An infusion of 3 grams (g) of tea leaves in 5 ounces of water is stronger than a regular cup of green tea (2 g of tea leaves brewed in 8 ounces of water), but Smithson says it’s possible to get the same benefits listed in the study by drinking several cups of regular green tea per day. But, she points out, green tea alone is unlikely to control blood sugar and cholesterol levels — you’ll need to eat a balanced diet that’s low in added sugars, simple carbohydrates, and saturated fat and monitor your numbers regularly.
Drinking green tea may also decrease the risk of developing type 2 diabetes, some scientific literature suggests. Research in the Annals of Internal Medicine found that people in Japan who drank 6 or more cups of green tea per day were 33 percent less likely to develop type 2 diabetes compared with people who drank less than 1 cup per week when adjusting for confounding factors like age and body mass index.
Green tea has a powerful antioxidant called polyphenol, which may give it anti-cancer, anti-inflammatory, and cholesterol-lowering benefits, according to a review published in November 2014 in the Journal of Food Processing and Technology. Polyphenols come from plants and help protect our cells from damage. Green tea has a few different types that make up around 40 percent of its dry weight.
In addition, green tea may have a calming effect on the mind and body. It contains the amino acid L-theanine, which Smithson says has a calming effect. According to a study published in October 2012 in the Journal of Physiological Anthropology, L-theanine may help reduce anxiety and prevent stress-related increases in blood pressure. “Having a chronic condition like diabetes can add stress and anxiety, so drinking a cup of green tea can offer a benefit of calmness,” she adds.
How Much Green Tea Should You Drink If You Have Diabetes?
Research suggests that there aren’t negative effects to drinking green tea, as long as you’re not adding sugar, says Winonah Hoffman, RN, nursing manager. When treating people with diabetes, Hoffman recommends never adding sugar to drinks; instead, she advises drinking unsweetened tea or tea with sugar alternatives, like stevia.
Stevia is a sugar substitute that comes from the leaves of the stevia plant. Hoffman likes it as an option for people with diabetes because it has less than 1 calorie and no carbs per packet. A study published in the journal Appetite suggests that of the low-calorie sweeteners commonly used by people with diabetes (including aspartame and sucrose), stevia was the only one shown to lower blood sugar and insulin levels after a meal.
If you find green tea to be too bitter, forgo using honey or table sugar (brown or white) and instead opt for a sweetener such as stevia.
When drinking green tea, the other thing to keep in mind is caffeine, which can affect blood sugar and blood pressure. The latter is of particular concern for people with type 2 diabetes, who are 2 to 4 times as likely to die of heart disease compared with people without type 2 diabetes, according to the American Heart Association.
A good way to see how you respond to the amount of caffeine in green tea is to check your blood sugar before drinking the tea and then one to two hours afterward, says Smithson. If you’re still in your target range before and after, you haven’t hit your limit. Smithson also recommends using a home blood pressure cuff to monitor blood pressure.
The good news is that green tea has much less caffeine than coffee or black tea. According to the Mayo Clinic, there’s about 25 to 29 milligrams (mg) per 8 ounces of brewed green tea compared with 95 to 165 mg for the same amount of brewed coffee and 25 to 48 mg for brewed black tea.
But if your body is sensitive to caffeine, it could still be a problem. That’s why it’s important to pay attention to your individual reaction.
Other Teas to Try to Better Manage Type 2 Diabetes
The difference between green, oolong, and black tea is how they’re processed. Green tea is made from fresh leaves, which are steamed to prevent fermentation. The tea keeps its green color and antioxidant compounds. Oolong tea is slightly fermented, and black tea is fully fermented.
Some people prefer black or oolong teas because they’re milder in taste (green tea can be a bit more bitter), says Hoffman. Compared with green tea, black and oolong teas don’t have the same antioxidant levels and have slightly more caffeine, but that doesn’t mean they’re a bad choice.
If you are sensitive to caffeine, herbal teas can be a great substitute. They don’t contain caffeine and can be rich with flavor. On this note, Arevalo recommends cinnamon tea for people with type 2 diabetes — for both taste and possible health benefits (cinnamon is packed with antioxidants). There’s also some evidence that cinnamon might help control blood sugar in people with type 2 diabetes in larger amounts.