Increasing coffee intake will reduce the incidence of type 2 diabetes.

The study found that if the average daily coffee intake increased by one and a half cups in the past four years, the incidence of Ⅱ diabetes decreased by 11%, which undoubtedly reduced the risk of Ⅱ diabetes. The increase in coffee and tea intake is associated with a decrease in the incidence of Ⅱ diabetes, but little is known about the underlying mechanism of this link, and until now, the mystery has finally been solved.

According to a recent study published in the European Diabetes Research Association Diabetes (Diabetologia) journal, if the average daily coffee intake increased by one and a half cups (about 360ml) over a four-year period, the incidence of Ⅱ diabetes decreased by 11%. Dr. Frank Hu, Dr. Shilpa Bhupathiraju and colleagues from the Harvard School of Public Health led the study.

Increased coffee and tea intake is associated with a decrease in the incidence of Ⅱ diabetes, but little is known about the underlying mechanism of this link. The authors investigated the link between changes in coffee and tea intake over four years and the incidence of Ⅱ diabetes over the next four years.

The authors used observational data from three major prospective studies in the United States: the Nurses' Health study (NHS) (1986 Mui 2006, for female nurses aged 30 to 55), NHSII (1991 Mui 2007, for young female nurses aged 25 to 42), and the Health Professional follow-up study (HPFS) (1986 Muir 2007, for male professionals aged 40 to 75). For 20 years, researchers collected detailed information about their diet, lifestyle, drug environment and other chronic diseases every two to four years.

Through these repeated measurements and long-term follow-up, the authors were able to analyze the relationship between changes in coffee and tea intake over four years and the incidence of type 2 diabetes over the next four years. They also investigated whether caffeinated and non-caffeinated coffee had different effects on the incidence of diabetes. The researchers evaluated the dietary data through a quadrennial food intake frequency questionnaire. In a subsequent supplementary questionnaire, respondents were asked to fill out whether they had type 2 diabetes. The final analysis process combined survey data including 48464 women in NHS, 47510 women in NHSII and 27759 men in HPFS.

The authors recorded 7269 cases of type 2 diabetes and found that participants who had increased their coffee intake over a four-year period (an average of 1 cup or more per day, with a median increase of 1.69 cups per day) had an 11% lower incidence of type 2 diabetes over the next four years than those with no change in coffee intake. Participants with reduced coffee intake (an average of one or more cups per day, with a median of 2 cups per day) were 17 percent more likely to develop type 2 diabetes. Tea intake was not associated with the incidence of type 2 diabetes.

People who had the highest coffee intake and were able to maintain this state-- known as "high-stability consumers" because they ate three or more cups of coffee a day-- had the lowest prevalence of type 2 diabetes. 37% lower than "low-stability consumers" (who consume one cup or less of coffee a day).

The authors say that the increase in the incidence of type 2 diabetes is related to a decrease in coffee intake, which means that the risk of the disease will change under the influence of coffee. But perhaps this link is potentially affected by some kind of adverse causal event: patients with disease (such as high blood pressure, cholesterol, cardiovascular disease or cancer) tend to be associated with the risk of type 2 diabetes. And they reduce their coffee intake after taking drugs. However, even if cases of cardiovascular disease or cancer were excluded during follow-up, the results would not change much.

Although the basic intake of decaffeinated coffee is associated with a decrease in the incidence of type 2 diabetes, changes in its intake do not affect the incidence of the disease. As for tea intake, the authors said: "We have found no evidence that changes in tea intake affected the incidence of type 2 diabetes over four years. This may be due to the fact that our respondents' tea intake did not change much over a four-year period, so it was not possible to fully calculate the correlation between them. At the same time, the respondents' overall low intake of tea is also a reason. "

"in these three research teams, the researchers followed more than 1.6 million participants for many years, and we observed an increase in coffee intake over a four-year period," the authors said. they had a lower incidence of type 2 diabetes over the next four years. Reduced coffee intake is associated with a higher incidence of type 2 diabetes. At the same time, we also found that changes in caffeinated coffee intake affected the incidence of type 2 diabetes, while changes in non-caffeinated coffee intake did not. And it has nothing to do with initial coffee intake and other dietary and lifestyle changes over the past four years. " They added: "changes in coffee eating habits can affect the incidence of diabetes in a relatively short period of time. Our findings confirm that higher coffee intake is associated with a lower incidence of type 2 diabetes, and we present novel evidence that changes in coffee eating habits are associated with the incidence of diabetes. "