Coffee consumption and type 2 diabetes – Part 3

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This is the third of three blog posts on the topic of coffee consumption and type 2 diabetes, concentrating on the potential mechanisms behind the effects of caffeine consumption on type 2 diabetes. Coffee and Health also houses current scientific information on a wide range of other coffee-related topics.

Potential mechanisms

The one thing still lacking with these associations between consumption of regular coffee, decaffeinated coffee or tea and a lower risk of developing type 2 diabetes, is a plausible mechanism.

Caffeine unlikely to play a role

Since coffee and tea are the main sources of caffeine in the diet in most countries, it is difficult to directly separate an effect of caffeine from coffee or tea. However, since decaffeinated coffee is reported to have a similar effect to regular coffee, it is unlikely that caffeine plays a role in the negative association for development of type 2 diabetes.

Antioxidant effect?

The most recent hypothesis looks at the effect of other coffee ingredients, in particular antioxidants like chlorogenic acid and trigonelline. These could play a role through their effect on subclinical inflammation, often associated with type 2 diabetes.

A Finnish study tested the effects of a progressively increasing coffee consumption in obese volunteers (in the first month participants abstained from coffee, for the second month 4 cups of coffee were consumed per day and in the third month, participants had 8 cups per day). Coffee consumption appeared to have beneficial effects on some signs of subclinical inflammation, considered to be risk factors for type 2 diabetes.

Because of its high levels of antioxidant compounds coffee could contribute to the total antioxidant capacity of the diet that is necessary to reduce oxidative stress. This in turn would lead to unfavourable conditions for the development of type 2 diabetes. This hypothesis has not yet been confirmed.

Other areas under investigation

A 2011 study from Harvard looked at the effects of caffeinated and decaffeinated coffee on biological risk factors for type 2 diabetes. The authors concluded that improvements in adipocyte and liver function may contribute to beneficial metabolic effects from long term coffee consumption.

Coffee consumption has been related to decreased risk of type 2 diabetes and high blood sugar among those with high levels of serum γ-glutamyltransferase. A 2012 study in a Japanese population found coffee drinking to be protective against glucose intolerance. Furthermore, they found grounds to continue research into the possible effect modifying serum γ-glutamyltransferase levels could have on the protective association between coffee and type 2 diabetes.

The association between moderate coffee consumption and reduced risk of developing type 2 diabetes has potentially important implications in light of the already high and increasing prevalence of this disease. However, the mechanisms underlying the effect of coffee need further investigation.

For more information on coffee and type 2 diabetes, and to view reference material, click here.

Presentations from experts present at the World Congress on Prevention of Diabetes and Its Complications (WCPD) can also be viewed here.

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