Little known tips to improve blood glucose control when drinking tea and coffee

The effect of caffeine on diabetes can often be confusing, especially when looking at the media who regularly post what appears to be contradicting stories on the subject. We are hoping to clear things up for you in this post, to put all the myths to one side and only look evidence that is backed up by science.

Whilst helping you to understand what might be happening in the body curing caffeine consumption, it is important to state that this is still not a heavily studied area.


Caffeine can cause fluctuations in blood glucose levels. Here’s why:

Raised levels of epinephrine (adrenaline).

This stress hormone can prevent your cells from processing as much sugar.

Sleep loss

Caffeine can take its toll on sleep or even contribute to insomnia. Lack of sleep can contribute to insulin resistance in the body for people with type 1 diabetes.

Protein blocking

It can block a protein called adenosine which in turn results in the body not clearing glucose from the blood as quickly.

All of the side effects mentioned above can result in higher blood glucose levels.

However, there is some good news!


Whilst caffeine may have a negative impact on blood glucose control, consumption of coffee has been proven to have positive health benefits, lowering the risk of:

  • Certain cancers
  • Cardiovascular disease
  • Strokes
  • Alzheimer’s disease
  • Parkinson’s disease

Coffee also contains polyphenols (a dietary antioxidant), magnesium and chromium. These nutrients have been shown to increase insulin sensitivity, which may help to offset the opposite effect of caffeine.


Similar to coffee, consumption of tea has been proven to have some health benefits. These include:

  • Maintaining healthy blood pressure
  • Preventing blood clots
  • Reducing risk of cardiovascular disease
  • Reducing risk of developing certain cancers

Tea also contains polyphenols (similar to coffee) which can increase insulin sensitivity. These can also help to prevent developments in type 2 diabetes.


If you plan on adding milk, cream or sugar/sweeteners to your caffeinated beverage then it is important to carb count and adjust your insulin accordingly. Certain studies have also shown that addition of milk may decrease the insulin-sensitising effects of tea. 


Everybody react differently to consumption of food and drinks. There is not, and possibly never will be a ‘one size fits all’ solution to caffeine consumption. However, with an increased knowledge it is easier to make informed decisions*.

It is important to note that results from studies on caffeine and diabetes remain inconsistent thus far. Knowing exactly what impact it could have on you will take some experimentation, and could be dependent on many things – including time of day, carb counts, physical activity, hormone levels and the amount of caffeine ingested.

*We do not recommend adapting any of your treatment plan without consulting a specialist. Our information is for informative purpose only.

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