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Coffee, Green Tea and Prognosis in Type 2 Diabetes Interview with:
Yuji Komorita, MD, PhD

Department of Medicine and Clinical
Science, Graduate School of Medical Sciences, Kyushu University
Maidashi 3-1-1, Higashi-ku, Fukuoka What is the background for this study?  

Response: Both green tea and coffee have been reported to confer health benefits, and reduce all-cause mortality in general population, respectively.
However, no study has investigated the combined impact of them on health or mortality.
We followed 4,923 Japanese patients with type 2 diabetes registered at the Fukuoka Diabetes Registry (median, 5.3 years; follow-up rate, 99.5%). What are the main findings? 

Response: Drinking 4 or more daily cups of green tea was associated with 40% lower risk of death, and 2 or more cups of coffee was associated with 41% lower risk. Furthermore, the combination of 4 or more cups of green tea and 2 or more cups of coffee every day was associated with 63% lower risk of death.
We have shown that higher consumption of green tea and coffee was associated with reduced all-cause mortality, and their combined effect appeared to be additive in people with type 2 diabetes. What should readers take away from your report? 

cup-of-tea-green-teaResponse: Green tea and coffee, and their combined consumption habits may improve the prognosis of people with diabetes. However, because this study is observational study, drinking green tea and coffee does not simply mean to extend your lifespan. What recommendations do you have for future research as a result of this work? 

Response: Beverages such as tea and coffee are strongly related to diet and are also affected by income, social status, family background, and health consciousness. Further research is needed to prove that green tea and coffee work independently of these confounding factors.
There are racial differences in the metabolism of tea and coffee, and the effects may differ depending on the underlying disease. I think it is also necessary to elucidate the interaction with genetic background or other therapeutic agents. Is there anything else you would like to add?

Response: Familiar beverages such as green tea and coffee may have health-promoting effects. It was suggested that the fusion of food and beverage habits associated with globalism may generate new evidence of nutritional science.

There is no conflicts of interest relevant to this article exist. 


Komorita Y, Iwase M, Fujii H, et al

Additive effects of green tea and coffee on all-cause mortality in patients with type 2 diabetes mellitus: the Fukuoka Diabetes Registry

BMJ Open Diabetes Research and Care 2020;8:e001252. doi: 10.1136/bmjdrc-2020-001252


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Last Updated on October 26, 2020 by Marie Benz MD FAAD