Can coffee help reduce risk of type 2 diabetes?

November 3, 2018
Mattias Carlström, Associate Professor of Physiology, Department of Physiology and Pharmacology, Karolinska Institutet, Sweden

Type 2 diabetes (T2D) is a major and growing health problem across Europe and around the world, which is associated with increased morbidity and mortality. The costs of treating T2D and associated complications related to the condition are also increasing. With this in mind, it is important to explore and acknowledge nutrition-based strategies for the prevention and treatment of the disease.

In October this year, renowned experts in diabetes met at the European Association for the Study of Diabetes (EASD) 2018 Annual Meeting in Berlin, Germany to discuss the latest research in diabetes aetiology, prevention, treatment and care. The Institute for Scientific Information on Coffee (ISIC) held a symposium at the conference on the topic of coffee and T2D, during which I presented the results of a recent meta-analysis I co-authored with Susanna C. Larsson (Karolinska Institutet), titled ‘Coffee consumption and reduced risk of developing type 2 diabetes: a systematic review and meta-analysis’ [1]. Professor Kjeld Hermansen, Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Denmark, discussed the potential mechanisms behind the association between coffee consumption and reduced risk of diabetes.

The conclusion of the meta-analysis I presented, based on 30 prospective studies and almost 1.2 million participants, is that, the pooled relative risk of developing T2D when comparing the highest coffee consumers (median 5 cups of coffee per day) versus the lowest (median 0 cups of coffee per day) was 0.71; in other words the highest coffee consumers had a 29% lower risk of developing T2D when compared to the lowest consumers [1].

The results from our study are in agreement with previous meta-analyses, which have suggested that drinking 3-4 cups of coffee per day is associated with an approximate 25% lower risk of developing T2D, compared to consuming none or less than 2 cups per day [2,3]. It is important to note that moderate coffee consumption is typically defined as 3–5 cups per day, based on the European Food Safety Authority’s review of caffeine safety [4].

Other key findings from our meta-analysis were:

  • The inverse relationship between coffee consumption and risk of T2D was dose-dependent, with a risk reduction of approx. 6% per 1 cup of coffee consumed per day.
  • The inverse relationship between coffee consumption and risk of T2D was consistent across different geographical regions (i.e. Europea, US and Asia) [1].
  • The inverse association between coffee consumption and risk of T2D was shown in both men and women, and although there were no clear differences between the sexes the effect was slightly greater in women1
  • Both caffeinated and decaffeinated coffee were associated with similar risk reduction of T2D, although the inverse relationship appeared to be somewhat stronger for caffeinated coffee [1].

At the symposium, Professor Hermansen presented a summary of the research that has been undertaken to identify and understand the potential mechanisms, suggesting that a number of routes may be involved including an antioxidant effect, an anti-inflammatory effect, thermogenic effects or modulation of microbiome diversity. He highlighted a number of potentially clinically relevant compounds present in coffee, including: caffeine, hydroxycinnamic acids, trigonelline, diterpenes e.g. cafestol and kahweol and caffeic acid. Many of the proposed underlying mechanisms, contributing to the favourable metabolic and cardiovascular effects of coffee, were summarized in the second part of our comprehensive review article [1].

In the future, long-term randomised placebo-controlled trials are needed to confirm the observed protective association between coffee consumption and T2D risk, and to help understand the underlying mechanisms of this relationship more in detail.

To read the ISIC EASD symposium report titled, ‘Coffee and type 2 diabetes: A review of the latest research’, click here. To watch a short video about my research into the association between coffee consumption and T2D, click here.


  1. Carlström M., Larsson S.C. (2018) Coffee consumption and reduced risk of developing type 2 diabetes: a systematic review with meta-analysis. Nutr Rev, 76(6):395–417
  2. Huxley R. et al. (2009) Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes Mellitus. Arch Int Med, 169:2053-2063.
  3. Ding M. et al. (2014) Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: A systematic review and dose response meta-analysis. Diab Care, 37(2):569-586.
  4. EFSA (2015) Scientific Opinion on the Safety of Caffeine, EFSA Journal, 13(5):4102.

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