Coffee Each Day Might Keep Diabetes Away

TUESDAY, March 9, 2004 (HealthDayNews) -- Researchers have uncovered an intriguing upside to that daily jolt of java.

A large-scale, long-term study of Finnish men and women found the higher your coffee consumption, the lower your risk of type 2 diabetes.

The researchers, whose study appears in the March 10 issue of the Journal of the American Medical Association, can't explain the association, but they do have some theories.

"There are many potential effects, since coffee has very many compounds, including (just mentioning a few) magnesium, caffeine, chlorogenic acid, etc.," says study author Dr. Jaakko Tuomilehto, of the National Public Health Institute in Helsinki. "Maybe chlorogenic acid is the most potent, but it is possible that the presence of several active agents at the same time will enhance the effect of coffee on the risk of type 2 diabetes."

Coffee is the most consumed beverage in the world, and Finnish people drink more per capita than any other nationality, the study authors point out.

It was already known that caffeine stimulates the beta cells in the pancreas to secrete insulin. The hormone insulin ushers glucose out of the bloodstream and into cells, where it can be used for energy. According to the American Diabetes Association, people with type 2 diabetes do not produce enough insulin, so glucose lingers in the blood vessels, eventually causing serious damage. Or the cells ignore the insulin, so it isn't utilized properly in the body.

The current study combined surveys that had been conducted in 1982, 1987 and 1992 among 6,974 Finnish men and 7,655 Finnish women between the ages of 35 and 64, none of whom had a history of stroke, coronary heart disease or type 2 diabetes at the start of the study. The participants filled out a questionnaire that included questions on medical history, socioeconomic factors, physical activity and smoking status, as well as alcohol, coffee and tea consumption. They were followed for about 12 years.

Women who drank three to four cups of coffee per day had a 29 percent reduced risk of diabetes. Those who drank at least 10 cups a day had a 79 percent reduced risk.

Men who drank three to four cups of coffee a day had a 27 percent lower risk while those who drank at least 10 cups a day had a 55 percent lower risk.

The study also found that men who drank pot-boiled coffee faced three times the risk of diabetes compared to men who drank filtered coffee.

That may have to do with the length of time the coffee was exposed to high temperatures, says Dr. Stuart Weiss, an assistant clinical professor of medicine at New York University School of Medicine in New York City. "Filtered coffee doesn't get quite as hot for as long, so some of the possible biologically active compounds are not broken down," he explains.

The research presents some interesting pharmaceutical possibilities, Weiss adds.

"It's very interesting for the basic scientist to take a look to see if there aren't compounds in the coffee that improve insulin sensitivity. That would be the exciting thing for me, to see potential new therapeutic agents being derived from coffee," he says. "High coffee consumption is linked to a lot of bad behaviors," including smoking.

A research letter in the same issue of the journal found that adding one additional cup of coffee per day was associated with a .16-units higher insulin sensitivity.

The letter points out that coffee consumption is also associated with an unhealthy lifestyle, including consumption of sugars and pastries and smoking. These variables were controlled for in this study.

Tea consumption was also related to improved insulin sensitivity.

While the study says chlorogenic acid may inhibit glucose-6-phosphatase activity, which is involved in regulating glucose levels, the researchers hypothesize that something other than caffeine was responsible for the effect. That could be phenolic compounds, which have antioxidant properties, and that antioxidant activity might decrease insulin resistance.

"This is in agreement with our results, but it is also possible that coffee also has an effect on insulin production/secretion in the pancreas, not only on insulin sensitivity in tissues," Tuomilehto says.

In either case, more research is needed, including, Tuomilehto says, "trials using different doses and different types of coffee in a strictly controlled setting; assessment of the interaction between coffee and known susceptibility genes for type 2 diabetes; and evaluation of effects of coffee drinking in conjunction with weight control and increased physical activity in the prevention of type 2 diabetes."

More information

For more on type 2 diabetes, visit the National Diabetes Information Clearinghouse or the American Diabetes Association.