Can coffee prevent diabetes?

Q: I recently read a newspaper article that says coffee can prevent diabetes? Is there scientific evidence that shows this is true? I’m very interested on this matter because we have a strong family history of diabetes and it would be nice if all I need to do to prevent getting the disease is drink coffee.

Willie O., Davao City

A: The results of several studies conducted in the last 10 years on the relationship between coffee drinking and diabetes mellitus indeed suggest that coffee may have some preventive effect on diabetes mellitus.

The first of these studies—which triggered many subsequent ones—employed more than 17,000 Dutch men and women between 30 to 60 years old as subjects and was conducted by a group of Dutch scientists from Vrije University in Amsterdam. The results of the study were discussed in the article entitled “Coffee Consumption and the Risk of Type 2 Diabetes Mellitus,” which was published in the November 2002 issue of Lancet (a reputable British medical journal). In brief, the study showed that “coffee consumption was associated with substantially lower risk of clinical type 2 diabetes.” What’s more, the more coffee one drinks the better, because those subjects who drank seven or more cups of coffee a day were 50 percent less likely to develop diabetes than those who drank less.

Several succeeding studies conducted in Europe, Japan and the United States have essentially confirmed the Dutch group’s findings that habitual coffee consumption is associated with a substantially lower risk of type 2 Diabetes Mellitus, the type of diabetes that accounts for about 90% of all diabetes cases. One American study has also apparently uncovered the reason for this association. They found out that coffee raises the amount of sex hormone-binding globulin (SHBG) in the blood, and higher levels of SHBG are known to lower the risk of developing Type 2 diabetes.

However, before you start drinking coffee by the gallons, let me tell you that the existing evidence on the preventive benefit of coffee on diabetes is still very inconclusive. Besides, it seems that a person has to be a habitual heavy coffee drinker (i.e., seven cups or more a day) to benefit from the preventive effect of the beverage coffee on diabetes. And drinking seven cups of coffee per day may just be enough to create other health problems.

Regular heavy consumption of coffee can raise blood cholesterol levels and increase the risk of osteoporosis or brittle bone disease. It also raises one’s stress level. It, likewise, stains teeth and contributes to bad breath. It can also lead to gastrointestinal problems like heartburn and hyperacidity.

Coffee also increases the heart rate and blood pressure although these effects are more likely transient in nature and cause no permanent damage to the cardiovascular system.

Incidentally, heavy coffee drinking may prevent type 2 diabetes, but for those who already have diabetes, the habit may aggravate the condition. Several studies have shown that in habitual coffee drinkers with type 2 diabetes mellitus, caffeine has adverse effects on glucose metabolism, producing higher average day-time glucose concentrations.

Coffee is one of the most popular forms of beverage worldwide. About 10 billion pounds of the substance are consumed yearly throughout the world. It will certainly be nice if in the future, albeit very unlikely, it is proven that it can prevent diabetes even at low doses. In any case, enjoy the drink, but don’t abuse it.