Two types of hot drink a day cut diabetes death risk 60 per cent

People with diabetes live longer if they drink several cups of coffee and green tea every day, according to a study. Drinking four or more cups of green tea plus at least two cups of coffee a day lowers the overall risk of death among diabetes patients by more than 60 per cent, according to the findings.

Researchers found enjoying plenty of daily cuppas is linked to a lower risk of dying from any cause among people with type 2 diabetes, with a 63 per cent lower risk of death over a period of around five years. Study author Dr Yuji Komorita, from Kyushu University in Japan, said: "People with type 2 diabetes are more prone to circulatory diseases, dementia, cancer, and bone fractures.

"And despite an increasing number of effective drugs, lifestyle modifications such as exercise and diet remain a cornerstone of treatment."

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Dr Komorita added: "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."

Previous research suggests that drinking green tea and coffee regularly could be beneficial for health because of the various bioactive compounds – chemicals which promote good health – these beverages contain. But few of these studies have been carried out in people with diabetes.

In their new study, the researchers decided to explore the potential impact of green tea and coffee, separately and combined, on the risk of death among people with the condition. They tracked the health of almost 5,000 Japanese people with type 2 diabetes, with an average age 66, for an average of around five years.

Participants each filled in a 58-item food and drink questionnaire, which included questions on how much green tea and coffee they drank every day. They also provided background information on lifestyle factors such as regular exercise, smoking, alcohol consumption and nightly hours of sleep.

Measurements of height, weight and blood pressure were also taken, as well as blood and urine samples to check for potential underlying risk factors. Some 607 of the participants didn’t drink green tea while 1,143 drank up to a cup a day. A total 1,384 drank between two to three cups and 1,784 drank four or more.

Nearly 1,000 participants did not drink coffee, 1,306 drank up to one cup daily, 963 drank a cup every day and 1,660 drank two or more cups. During the monitoring period, 309 people died. The main causes of death were cancer, 114 people, and cardiovascular disease, 76 people.

Dr Komorita said: "Compared with those who drank neither beverage, those who drank one or both had lower odds of dying from any cause, with the lowest odds associated with drinking higher quantities of both green tea and coffee. Drinking up to one cup of green tea every day was associated with 15 per cent lower odds of death while drinking two to three cups was associated with 27 per cent lower odds. Getting through four or more daily cups was associated with 40 per cent lower odds."

Among coffee drinkers, up to one daily cup was associated with 12 per cent lower odds while one cup a day was associated with 19 per cent lower odds. And two or more cups was associated with 41 per cen lower odds. The risk of death was even lower for those who drank both green tea and coffee every day. The risk was slashed by more than half for those who drank two to three cups of green tea plus two or more cups of coffee.

While it was greater still, at 58% lower for four or more cups of green tea plus one cup of coffee every day, and 63 per cent lower for a combination of four or more cups of green tea and two or more cups of coffee every day. Commenting on its limitations, Dr Komorita said: "This is an observational study and as such, can’t establish cause."

Researchers also pointed to several caveats, including the reliance on subjective assessments of the quantities of green tea and coffee drunk. Information was not gathered on other potentially influential factors, such as household income and educational attainment, and the green tea available in Japan may not be the same as that found elsewhere, they add.

Dr Komorita added: "The biology behind these observations isn’t fully understood. Green tea contains several antioxidant and anti-inflammatory compounds, including phenols and theanine, as well as caffeine. Coffee also contains numerous bioactive components, including phenols. As well as its potentially harmful effects on the circulatory system, caffeine is thought to alter insulin production and sensitivity."

All study participants had been enrolled in The Fukuoka Diabetes Registry, a multicentre prospective study looking at the effect of drug treatments and lifestyle on the lifespan of patients with type 2 diabetes. The findings were published in the online journal BMJ Open Diabetes Research and Care.