Changes in Coffee Intake and Subsequent Risk of Type 2 Diabetes: Three Large Cohorts of US Men and Women

Study Questions:

Is coffee or tea consumption associated with an increased risk for type 2 diabetes?


Data from four large prospective cohorts were used for the present analysis. These cohorts included the Nurses’ Health Study (NHS; 1986–2006, 48,464 women), the Nurses’ Health Study II (NHS II; 1991–2007, 47,510 women), and the Health Professionals Follow-up Study (HPFS; 1986–2006, 27,759 men). The NHS was initiated in 1976 as a prospective cohort study of female registered nurses, 30–55 years of age, from 11 US states. The NHS II consists of younger female registered nurses, ages 25–42 years at baseline (1989). The HPFS is a prospective cohort study of male health professionals, 40–75 years of age, from all 50 states, which began in 1986. Cohort members received validated questionnaires at baseline and every 2 years thereafter to update their information on medical history, lifestyle, potential risk factors, and disease diagnosis.


During 1,663,319 person-years of follow-up, a total of 7,269 cases of incident type 2 diabetes were reported. Participants who increased their coffee consumption by more than one cup/day (median change = 1.69 cups/day) over a 4-year period had an 11% (95% confidence interval [CI], 3%–18%) lower risk of type 2 diabetes in the subsequent 4 years compared with those who made no changes in consumption. Participants who decreased their coffee intake by more than one cup/day (median change = −2 cups/day) had a 17% (95% CI, 8%–26%) higher risk for type 2 diabetes. Changes in tea consumption were not associated with type 2 diabetes risk.


The investigators concluded that increasing coffee consumption over a 4-year period is associated with a lower risk of type 2 diabetes, while decreasing coffee consumption is associated with a higher risk of type 2 diabetes in subsequent years.


These are interesting findings, which suggest that coffee intake may be protective for development of diabetes. However, coffee intake is only one component of a healthy lifestyle. Regular physical activity and a diet high in fruits and vegetables should be recommended irrespective of the amount of coffee consumed.

Clinical Topics: Diabetes and Cardiometabolic Disease, Prevention, Diet

Keywords: Life Style, Food Habits, Diabetes Mellitus, Type 2, Metabolic Syndrome X, Fruit, Caffeine, Tolbutamide, Vegetables, Tea, Motor Activity, Cardiovascular Diseases, Confidence Intervals, Diet, Coffee

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