Coffee consumption and risk of cardiovascular events and all-cause mortality among women with type 2 diabetes

W. L. Zhang 0 2 3 E. Lopez-Garcia 0 2 3 T. Y. Li 0 2 3 F. B. Hu 0 2 3 R. M. van Dam 0 2 3 0 E. Lopez-Garcia Universidad Autnoma de Madrid , Madrid, Spain 1 ) Sino-German Laboratory for Molecular Medicine, FuWai Cardiovascular Hospital and Cardiovascular Institute, Peking Union Medical College and Chinese Academy of Medical Sciences , Beijing 100037, China 2 F. B. Hu Department of Epidemiology, Harvard School of Public Health , Boston, MA, USA 3 E. Lopez-Garcia CIBER Epidemiologia y Salud Pblica (CIBERESP), Barcelona , Spain URL: www.ciberesp.es Aims/hypothesis Coffee has been linked to both beneficial and harmful health effects, but data on its relationship with cardiovascular disease and mortality in patients with type 2 diabetes are sparse. Methods This was a prospective cohort study including 7,170 women with diagnosed type 2 diabetes but free of cardiovascular disease or cancer at baseline. Coffee consumption was assessed in 1980 and then every 2-4 years using validated questionnaires. A total of 658 incident cardiovascular events (434 coronary heart disease and 224 stroke) and 734 deaths from all causes were documented between 1980 and 2004. Results After adjustment for age, smoking and other cardiovascular risk factors, the relative risks were 0.76 (95% CI 0.50-1.14) for cardiovascular diseases (p trend = 0.09) and 0.80 (95% CI 0.55-1.14) for all-cause mortality (p trend = 0.05) for the consumption of 4 cups/day of caffeinated coffee compared with non-drinkers. Similarly, multivariable RRs were 0.96 (95% CI 0.66-1.38) for cardiovascular diseases (p trend = 0.84) and 0.76 (95% CI 0.54-1.07) for all-cause mortality (p trend = 0.08) for the consumption of 2 cups/day of decaffeinated coffee compared with non-drinkers. Higher decaffeinated coffee consumption was associated with lower concentrations of HbA1c (6.2% for 2 cups/day versus 6.7% for <1 cup/ month; p trend = 0.02). Conclusions These data provide evidence that habitual coffee consumption is not associated with increased risk of cardiovascular diseases or premature mortality among diabetic women. - Abbreviations CVD Cardiovascular disease MI Myocardial infarction NHS Nurses Health Study Type 2 diabetes mellitus increases the risk of cardiovascular disease (CVD) and mortality two- to fourfold [1]. Moreover, diabetes increases the risk of CVD to a greater extent in women compared with men, and diabetes may eliminate womens protection against coronary heart disease [2]. Coffee drinking is widespread across the world; more than 50% of Americans drink coffee, and the average per capita intake is about two cups per day [3]. Thus, even small health effects of coffee could have a large impact on public health. Habitual coffee consumption has been associated with better glucose tolerance in persons without diabetes [4]. In addition, coffee contains phenolic compounds with antioxidant properties [5], and may affect the process of atherosclerosis favourably by preventing oxidation of LDL-cholesterol [6] and inhibiting platelet aggregation and thrombogenesis [7, 8]. On the other hand, caffeine intake acutely raises blood pressure [9, 10], homocysteine levels [11] and postprandial glucose levels [12] in short-term trials. Because of these complex physiological effects of coffee and because at least partial tolerance of the haemodynamic effects of caffeine typically develop with long-term use [13], it is difficult to extrapolate findings from short-term metabolic studies to the effects of long-term use of coffee. The relationship between coffee consumption and CVD and mortality remains controversial [14, 15]. While most recent prospective studies have suggested that coffee consumption is not associated with an increased risk of coronary heart disease and mortality in the general population [1620], data on diabetic patients are sparse [21]. Therefore, we prospectively examined the relationship between coffee consumption and the incidence of coronary heart disease and stroke and all-cause mortality among women with type 2 diabetes in the Nurses Health Study (NHS). Study population The NHS cohort was established in 1976 when 121,700 female registered nurses, 3055 years old and residing in 11 large US states, completed a postal questionnaire about their medical history and lifestyle. The present study included the 7,170 women who reported physician-diagnosed type 2 diabetes on any questionnaire between 1976 and 2004 (1,552 prevalent diabetic women in 1980 and 5,618 incident diabetic women during the followup). Women with diabetes diagnosed before the age of 30 years, or with a history of CHD (including myocardial infarction [MI], angina, and/or coronary revascularisation), stroke or cancer reported on the 1980 questionnaire (when diet was first assessed) or before, were excluded at baseline. This study was approved by the institutional review board at Brigham and Womens Hospital and return of the questionnaires was assumed to imply informed consent. Confirm (...truncated)