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Coffee may reduce diabetes risk, but worsen symptoms

Coffee beans in coffee cup isolated on white

Increased coffee consumption may reduce risk of type-2 diabetes, but once you have the disease, research shows coffee seems to increase insulin resistance and could make matters worse.

Research in April 2014 that a coffee bean ‘pill’ would beat Type 2 diabetes, based on the theory that naturally occurring chlorogenic acids in coffee beans could help control blood glucose levels and weight, has been attacked by ‘experts’.

The original report even claimed that drinking seven cups of coffee a day was already known to cut the risk of diabetes by 50 per cent; and that roasting the beans for coffee (which breaks down the acids) would give even better results.

However, Dr Matthew Hobbs, Head of Research at Diabetes UK, said, “Although there is some preliminary evidence to suggest that an increased intake in polyphenols and/or flavanoids, for example, through tea and coffee, can reduce the risk of Type 2 diabetes and help manage the condition, research in this area is limited and has for the most part been carried out on small and unrepresentative samples.

In particular, there has been a lack of investigation into understanding why this may happen, what specific ingredient may be causing positive effects or what the possible risks would be of increasing intake of tea and coffee, for example, to seven cups a day.

There is nowhere near enough evidence to support advice for people at risk of Type 2 to increase their intake of coffee in any form”.

However, this all came about because researchers from Harvard published a study of over 100,000 men and women and showed that coffee may help prevent type-2 diabetes in 2014. The researchers found that people who increased their coffee consumption by 1 cup per day over a 4-year period had an 11% lower risk of diabetes, while those who decreased their consumption by 1 cup per day had a 17% increased risk.

The Mayo Clinic advises that drinking coffee may raise or lower blood sugar depending upon the individual. The effect is due to caffeine(1).

Coffee contains polyphenols which are known to reduce inflammation in the body and Diabetes UK believes this may have something to do with the findings. Generally though coffee increases insulin resistance and may worsen type-2 diabetes symptoms if you already have the disease. It certainly does seem capable of increasing blood sugar levels.


  1. Mayo Clinic; caffeine, diabetes
  2. Changes in Coffee intake and subsequent risk of Diabetes