What’s the mechanism linking coffee to type 2 diabetes risk reduction?

December 11, 2015
Expert comment from Dr. Duane Mellor, Assistant Professor in Dietetics at the University of Nottingham, UK and Lead of the European Specialist Dietetic Network for Diabetes at the European Federation of the Associations of Dieticians (EFAD)

The prevalence of type 2 diabetes in Europe

As highlighted by the latest IDF research, in Europe, approximately 60 million people have diabetes, including 23.5 million undiagnosed cases [1]. In 2015, 627,000 diabetes-related deaths were recorded in people aged 20-79 [1]. The prevalence of type 2 diabetes is increasing and is linked to lifestyle, especially unhealthy food choices and increased levels of inactivity which has resulted in rising levels of obesity. With this in mind and the frequent negative messages, it is important to acknowledge behaviours and choices can help to reduce the risk of developing type 2 diabetes, especially those relating to diet, which at least in principle, can be relatively easy to change.

Coffee consumption and its association with type 2 diabetes risk

There is currently an emerging body of research that increasingly suggests an association between coffee consumption and a reduced risk of developing type 2 diabetes. For example, drinking three to four cups of coffee per day is associated with an approximate 25% lower risk of developing type 2 diabetes [2,3]. However, less is known about the exact mechanisms behind this association. Researchers are investigating, focusing on the role of compounds previously thought to behave as antioxidants but are more likely to moderate inflammation markers in the body, however further research is required to understand this association in detail. For this reason, researchers are not yet able to advise whether coffee should be actively recommended to patients with type 2 diabetes or even those at risk [4].

Potential mechanisms

A number of recent papers have concluded that consumption of both caffeinated and decaffeinated coffee is associated with a reduced risk of developing type 2 diabetes [4,5]. For this reason, it is unlikely that caffeine is the key active component. Other constituents of coffee are worth further investigation. For example, chlorogenic acid and trigoneline which are found in coffee, can have a beneficial impact on results of oral glucose tolerance tests, used to detect diabetes risk [6].

Further research has considered the role of inflammatory markers in the body, believed to be associated with the development of type 2 diabetes.  A recent study suggested that serum amyloid-A levels may be key mediators in the inverse association between habitual coffee intake and type 2 diabetes development, and concluded that the anti-inflammatory effect of several coffee components may be responsible for this protective effect [7].

Many other mechanisms have also been considered, but at this stage, no firm conclusions have been drawn.  Clearly there is a need for further research in this area to understand the mechanisms behind the association between coffee and a reduced risk of type 2 diabetes. There is no doubt that a better understanding would encourage beneficial dietary choices in those at risk, and provide supporting evidence to healthcare professionals dispensing advice to patients and the general public.

Coffee may have benefits that could help to reduce the risk of developing type 2 diabetes because of things it naturally contains. How you consume your coffee, and what you consume it with also counts.  Adding sugar, syrups and cream with a muffin or cake on the side is likely to increase your energy intake, which may encourage weight gain and increase your risk of type 2 diabetes. What goes with and in your coffee should be considered if you are seriously looking to improve your health.


  1. International Diabetes Federation (2015) ‘IDF DIABETES ATLAS 7th Edition’, Available at: http://www.diabetesatlas.org/
  2. Jiang X. et al. (2014) Coffee and caffeine intake and incidence of type-2 diabetes mellitus: a meta-analysis of prospective studies. European Journal of Nutrition, 53(1):25–38
  3. Huxley R. et al. (2009) Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes Mellitus. Arch Intern Med,169:2053-63
  4. Akash M.S. et al. (2014) Effects of coffee on type 2 diabetes mellitus. Nutrition, 30(7-8):755-63
  5. Ding M. et al. (2014) Caffeinated and Decaffeinated Coffee Consumption and Risk of Type 2 Diabetes: A Systematic Review and a Dose-Response Meta-analysis, Diabetes Care, 37 (2):569-86
  6. van Dijk A.E. et al. (2009) Acute effects of decaffeinated coffee and the major coffee components chlorogenic acid and trigonelline on glucose tolerance. Diabetes Care, 32:1023-1025
  7. Koloverou E. et al. 2015, The evaluation of inflammatory and oxidative stress biomarkers on coffee-diabetes association: results from the 10-year follow-up of the ATTICA Study (2002–2012). European Journal of Clinical Nutrition, 69(11):1220-5

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