Medical Investigations: Coffee and Diabetes

The effect of coffee on diabetes, when presented in the media can often be confusing.

News stories can in the same week tout the benefits coffee can have on diabetes and shoot down coffee as being unhelpful for blood sugar levels.

This doesn’t mean the articles are contradictory though.

Put slightly more simply, coffee contains different chemicals, some of which have beneficial effects whereas others can have a less beneficial effect, such as caffeine which can impair insulin in the short term.

Caffeine and blood sugar levels

Regular high caffeine consumption, over a 4 week period, has been shown to impair insulin sensitivity in people with type 2 diabetes. 

Whilst the researchers found a relationship between higher coffee consumption and lower sensitivity to insulin, they recognised that the rapid transition to having more coffee may have produced an atypical or emphasised response by the body.

Benefits of coffee

Coffee has been shown to lower risks of the following conditions:

• Type 2 diabetes
• Cancer - such as endometrial cancer and aggressive prostate cancer






• Cardiovascular disease
• Strokes
• Alzheimer's disease
• Parkinson's disease

Coffee contains polyphenols, which are a molecule that anti-oxidant properties which are widely believed to help prevent inflammatory illnesses, such as type 2 diabetes, and anticarcinogenic (anti-cancer) properties.

As well as polyphenols, coffee contains the mineral magnesium and chromium. Greater magnesium intake has been linked with lower rates of type 2 diabetes.

The blend of these nutrients can be helpful for improving insulin sensitivity, which may help to offset the opposite effects of caffeine.

Coffee and prevention of diabetes

Coffee and its effect on risks of developing type 2 diabetes have been studied a number of times and has indicated a notably lower risk of type 2 diabetes being associated with coffee drinkers.

A 2009 study of 40,000 participants noted that consumption of 3 cups of tea or coffee a day lead to a 40% lower risk of type 2 diabetes developing. 

A study of healthcare professionals in the US and UK, published in 2014, showed that those that increased their consumption of coffee experienced an 11% decrease in risk of type 2 diabetes over the next 4 years.

Contribution by Yaribeth Galvez club memberships white coat