Daily Coffee Consumption: A New Frontier in Diabetes Prevention!

Abstract & Commentary

By Rahul Gupta, MD, MPH, FACP, Clinical Assistant Professor, West Virginia University School of Medicine, Charleston, WV. Dr. Gupta reports no financial relationships relevant to this field of study.

Synopsis: Regardless of the caffeine status, coffee intake was associated with reduced risk of type 2 diabetes while sugar-sweetened beverages were associated with a higher risk.

Source: Bhupathiraju SN, et al. Caffeinated and caffeine-free beverages and risk of type 2 diabetes. Am J Clin Nutr 2013;97:155-166.

In the United States, type 2 diabetes (T2D) has become a major cause of heart disease and stroke. In fact, death rates for heart disease and the risk of stroke for a patient with diabetes are about 2-4 times higher than those of a non-diabetic. Additionally, two-thirds of adults who report having diabetes also report being hypertensive. It is estimated that the average medical expenses for someone with diabetes are more than twice that of someone without diabetes. Since 1990, the annual number of new cases of diagnosed diabetes in U.S. adults has more than tripled.1 Overall, 25.8 million people or 8.3% of the total U.S. population suffers from diabetes. However, another 33% of U.S. adults have prediabetes, a condition where individuals have blood glucose levels that are higher than normal, but not high enough to be diagnosed as diabetes. Unfortunately, we now know that prediabetes can also place people at increased risk of developing T2D, heart disease, and stroke. However, less than 10% of U.S. adults with prediabetes report that they have ever been told of having prediabetes.

Development of T2D in patients with prediabetes is not inevitable. Studies have shown that people with prediabetes can prevent or delay the onset of diabetes by dietary modifications and physical activity leading to 5-7% weight loss.2 While several prospective epidemiologic studies in the past have concluded that ingestion of caffeinated and decaffeinated coffee can reduce the risk of diabetes, some short-term studies have paradoxically shown that glucose tolerance is reduced shortly after ingestion of caffeine or caffeinated coffee and suggest that coffee consumption could increase the risk of diabetes. Additionally, while it is known that the consumption of caffeinated sugar-sweetened beverages (SSBs), such as soft drinks, energy drinks, and iced tea, may increase the risk of T2D, it is not well known whether artificially sweetened beverages (ASBs) may have the same impact.

In their research, Bhupathiraju et al used data from the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS), two research projects that followed more than 74,000 women and 39,000 men for 24 and 22 years, respectively. The NHS was initiated in 1976 as a prospective cohort study of female registered nurses aged 30-55 years from 11 states and HPFS was initiated in 1986 as a prospective cohort study of male health professionals aged 40-75 years from all 50 states. Researchers documented 7370 new cases of T2D in the NHS population and 2865 new cases of T2D in the HPFS population during the follow-up period. Controlling for major lifestyle and dietary risk factors, analysis revealed that SSB intake was associated with statistically significant increased risk of T2D in both population groups. In the NHS group, caffeinated SSBs were associated with a 13% increased risk while non-caffeinated SSBs were associated with an 11% increased risk for T2D per serving consumed. Similarly, in the HPFS group, caffeinated SSBs were associated with a 16% increased risk while non-caffeinated SSBs were associated with a 23% increased risk for T2D. For ASBs, only caffeine-free intake was associated with a 6% higher risk of T2D. In contrast, consumption of coffee (regardless of caffeine presence) was associated with a lower risk of T2D. Specifically, in the NHS group, both caffeinated and decaffeinated coffee were associated with an 8% decreased risk while in the HPFS group, the decreased risk was 4% for caffeinated and 7% for decaffeinated coffee. Caffeinated tea (but not decaffeinated) was associated with a 5% lowered risk of T2D in the NHS population only.

Commentary

It is no surprise that sugary beverages, irrespective of the caffeine content, would lead to an increase in the incidence of T2D. However, in this study, the increased incidence remained even after adjusting for confounders, which may suggest a direct biological effect of sugars used in sodas, such as high-fructose corn syrup and sucrose. This study was noteworthy to find that whether one likes his or her coffee caffeinated or decaffeinated, the benefits now include the reduction in risk of developing T2D. Interestingly, in men, the study found greater benefits from decaffeinated than caffeinated. For tea drinkers, only women derived similar benefits with caffeinated tea. Coffee is the leading worldwide beverage after water. Collectively, results from this and several other epidemiological studies suggest that coffee consumption may help prevent several chronic diseases, including T2D, Parkinson’s disease, and liver disease (cirrhosis and hepatocellular carcinoma).3 The health-promoting properties of coffee are often attributed to its rich phytochemistry, including caffeine, chlorogenic acid, caffeic acid, hydroxyhydroquinone, and others. However, coffee consumption is associated with increases in several cardiovascular disease risk factors, including blood pressure, cholesterol, and homocysteine as well as side effects from caffeine overindulgence. Traditionally, drinking coffee is often thought to be linked to unhealthier habits, such as smoking and low levels of physical activity. However, for most adult patients, research suggests that consuming moderate amounts of coffee may have some evidence of health benefits, especially when taken without cream or sugar. So, the next time you find yourself recommending strategies, such as dietary modification and physical activity, to prevent the development of T2D in your patients, you may want to consider adding the recommendation for two to three cups of coffee per day (providing 200-300 mg/d of caffeine), which may be associated with an almost 25% lower risk. Compared with many other less healthy beverages in an average diet, coffee may seem like a healthy beverage these days.

References

1. Centers for Disease Control and Prevention. Diabetes Report Card. 2012. http://www.cdc.gov/diabetes/pubs/pdf/DiabetesReportcard.pdf. Accessed December 17, 2012.

2. Knowler WC, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med 2002;346:393-403.

3. Higdon JV, Frei B. Coffee and health: A review of recent human research. Crit Rev Food Sci Nutr 2006;46:101-123.