Researchers to follow-up recent study to look at potential role for calorie free caffeinated drinks.

Coffee is a rich source of caffeine and previous research has found that 3-5 cups daily can lower the risk of developing type 2 diabetes and cardiovascular disease.

However, less was known about what specific effects were from caffeine, when included in combination with other compounds in caffeinated food and drinks.

As part of a recent study, researchers looked at how to reliably establish the causal effects that caffeine provides in reducing the risk of developing type 2 diabetes and lowering body fat.

A report published in BMJ Medicine found high blood caffeine levels could have a positive impact in reducing body fat and associated complications including type 2 diabetes, obesity, and heart problems.

Researchers at the Karolinska Institutet, Stockholm in Sweden now believe that there is potential for further investigation into a role for calorie free caffeinated drinks and how they could lower the risk of developing obesity and type 2 diabetes.

Researchers said: “Caffeine is a widely consumed psychoactive substance. The main sources of caffeine globally are from coffee, tea, and soda drinks. Considering the extensive intake of caffeine worldwide, even its small metabolic effects could have important health implications.”

To find out what effect higher blood caffeine levels have on body fat and long-term risks of type 2 diabetes, researchers used a process of Mendelian randomisation.

This technique uses genetic variants to identify risk factors – in this case blood levels of caffeine – to find genetic evidence to support an outcome – such as weight (body mass index) and type 2 diabetes risk.

A woman drinking coffee.

Around 10,000 people of predominantly European ancestry took part in six long-term studies. Researchers looked at the roles of two common genetic variants (CTP1A2 and AHR genes) that are linked to the speed of caffeine metabolism in the body.

The results found that people who carry genetic variants linked with slower caffeine metabolism drank, on average, less coffee, yet had higher levels of caffeine in their blood than people who metabolise it faster to feel the stimulant effects.

People with higher genetically predicted blood caffeine levels reported lower weight and body fat in addition to a lower risk of type 2 diabetes.

Researchers then looked at how much lowering the risk of developing type 2 diabetes was driven by weight loss and found that almost half (43%) was due to the effect of caffeine.

This is explained by the known effects of caffeine in boosting metabolism, leading to increased fat burning and reduced appetite.

Researchers reported that a daily intake of 100mg of caffeine was estimated to increase energy expenditure by around 100 calories per day – that could in effect lower the risk of developing obesity.

Researchers acknowledged that there were limitations to the study as there were only two genetic variants examined and only people of a European background participating.

Researchers concluded: “Our Mendelian randomisation finding suggests that caffeine might, at least in part, explain the inverse association between coffee consumption and risk of type 2 diabetes.

“Randomised controlled trials are warranted to assess whether non-caloric caffeine containing beverages might play a role in reducing the risk of obesity and type 2 diabetes.”

Commenting on the study, previously DRWF-funded researcher Dr Katarina Kos, a senior lecturer in diabetes and obesity at the University of Exeter, said the research showed potential health benefits for people with high levels of caffeine in their blood, although any caffeinated drinks containing sugar and fat would offset the positive effects.

She added: “It does not study or recommend drinking more coffee, which was not the purpose of this research.”

Read the report in BMJ Medicine

Read more about type 2 diabetes

Find out more about DRWF-funded research

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