Increasing consumption of coffee associated with reduced risk of T2DM

New research published in Diabetologia (the journal of the European Association for the Study of Diabetes) shows that

Increasing coffee consumption by on average one and half cups per day (approx 360ml) over a four-year period reduces the risk of type 2 diabetes by 11%.

The research by Dr Frank Hu et al in Diabetolgia examined the associations between 4-year changes in coffee and tea consumption and risk of type 2 diabetes in the subsequent 4 years.

The authors used observational data from three large prospective, US-based studies in their analysis: the Nurses’ Health Study (NHS) (female nurses aged 30-55 years, 1986-2006), the NHS II (younger female nurses aged 25-42 years 1991-2007), and the Health Professionals Follow-up Study (HPFS) (male professionals 40-75 years, 1986-2006).

Detailed information on diet, lifestyle, medical conditions, and other chronic diseases was collected every 2 to 4 years for over 20 years.

The authors documented 7,269 incident type 2 diabetes cases, and found that participants who increased their coffee consumption by more than 1 cup/day (median change=1.69 cups/day) over a 4-year period had a 11% lower risk of type 2 diabetes in the subsequent 4-years compared to those who made no changes in consumption.

Participants who decreased their coffee intake by 1 cup a day or more (median change=-2 cups/day) had a 17% higher risk for type 2 diabetes. Changes in tea consumption were not associated with type 2 diabetes risk.

Those with highest coffee consumption and who maintained that consumption—referred to as  “high-stable consumers” since they consumed 3 cups or more per day—had the lowest risk of type 2 diabetes,  37% lower  than the “low-stable consumers” who consumed 1 cup or less per day.

The authors say that the higher risk of type 2 diabetes associated with decreasing coffee intake may represent a true change in risk, or may potentially be due to reverse causation whereby those with medical conditions associated with risk for type 2 diabetes (such as high blood pressure, elevated cholesterol, cardiovascular disease, cancer) may reduce their coffee consumption after diagnosis.

While baseline decaffeinated coffee consumption was associated with a lower type 2 diabetes risk, the changes in decaffeinated coffee consumption did not change this risk. Regarding tea consumption, the authors say: "We found no evidence of an association between 4-year increases in tea consumption and subsequent risk of type 2 diabetes."

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