Those with type 2 diabetes are more prone to circulatory diseases, dementia, cancer, and bone fractures, despite an increasing number of effective drugs and lifestyle modifications such as exercise, and diet which remain the cornerstone treatment.
For this study, the health of 4923 Japanese people enrolled in The Fukuoka Diabetes Registry with type 2 diabetes and a mean age of 66 were tracked for an average of 5.3 years. Each participant filled out a food and drink questionnaire and provided background information on lifestyle factors such as sleep patterns, activity level, as well as smoking and alcohol habits. Additionally, measurements of height, weight, and blood pressure were taken along with samples of urine and blood to check for potential underlying risk factors.
607 participants did not drink green tea, 1143 drank up to 1 cup per day, 1384 drank 2-3 per day, and 1784 drank 4 or more per day. 994 participants did not drink coffee, 1306 drank up to one cup per day, 963 drank 1 cup per day, and 1660 drank 2 or more cups per day.
During the follow-up period: 309 participants died with the main causes of death being 114 having cancer and 76 having cardiovascular disease. Those who drank one or both of the beverages had lower odds of dying from any cause compared to those who did not drink either, with the lowest odds being associated with drinking higher quantities of both beverages.
Based on the results, drinking up to one cup of green tea per day was associated with a 15% lower odds of death, drinking 203 cups was associated with 27% lower odds, and 4 or more cups of green tea per day was associated with 40% lower odds of death. Drinking up to one cup of coffee per day was associated with 12% lower odds, one cup a day was associated with 19% lower odds, and drinking 2 or more cups of coffee per day was associated with 41% lower odds of death.
Additionally, results indicate that those who drank both beverages had an even lower risk of death with those drinking 2-3 cups of green tea plus 2 or more cups of coffee per day having 51% lower risk of death, those drinking 4 or more cups of green tea plus one cup of coffee every day had a 58% lower risk, and those drinking the combination 4 or more cups of green tea plus 2 or more cups of coffee per day had 63% less risk of dying.
It was noted that due to the observational nature of this study a cause can’t be established. The study was also limited by several caveats including the reliance on subjective assessments of the quantities of the beverage drunk and reported, plus information was not gathered on other potentially influential factors such as education, household income.
The biology behind the observations is not fully understood, but the researchers explain that the green tea and coffee available in Japan may not be the same as in other countries, regardless the beverages contain several antioxidants, anti-inflammatory and bioactive compounds like phenols, theanine, and caffeine which may partially contribute to the results.
“This prospective cohort study demonstrated that greater consumption of green tea and coffee was significantly associated with reduced all-cause mortality: the effects may be additive,” the researchers conclude.
