Got type 2 diabetes? Then drink coffee or green tea everyday to prolong your life, suggests a new research study from Japan. 

Published in the British Medical Journal (BMJ) Open Diabetes Research & Care, the findings are controversial. That’s because caffeine also has the potential to increase blood pressure, which raises the risk of a heart attack or stroke. 

However, the researchers suggest that the positives from coffee and green tea, both of which contain caffeine in their natural state, outweigh the risks. 

In reaching that conclusion, the scientists observed over 4900 patients with type 2 diabetes in Japan. The mean age of the subjects was 66. They were questioned in respect to their green tea and coffee consumption, and had been diagnosed with diabetes for approximately five years. Drinking either green tea, coffee, or a combination of the two, was associated with reduced all-cause mortality. In fact, those in the study that drank both were 63% less likely to have died during the follow-up.

The magic number of each drink associated with a lower risk of death: four cups of green tea and two for coffee. 

Chemical compounds in green tea, such as epicatechins (EGCG) contain  antioxidant, anti-inflammatory, and antibacterial properties. And the more green tea consumed, research shows, the better able one is to manage or even reverse chronic diseases such as type 2 diabetes. Although there have been many studies conducted on green tea, coffee, and their individual constituents, this study was the first of its kind to investigate the association between green tea consumption and mortality in diabetic patients.

With coffee, the conclusion that it’s healthy for those with diabetes is murkier because of the beverage’s impact on the cardiovascular system. However, the researchers concluded that males in the study who drank more coffee experienced lower systolic blood pressure, took less high-blood pressure medication or antiplatelet drugs, and had less history of developing cardiovascular disease and cancer. 

Despite the conclusions, keep in mind that the study is observational. Thus, it offers no finite conclusions. It seems likely, though, that moderate green tea and coffee consumption (with coffee being more moderated that green tea) can be part of a healthy diet.