If you’re taking coffee before breakfast, read this carefully. Researchers have found that drinking coffee first thing can have a negative effect on blood sugar control — a risk factor for diabetes and heart disease.

For the study, published in the journal British Journal of Nutrition, the research team looked at the effect of broken sleep and morning coffee across a range of different metabolic markers.

“The results show that whilst one night of poor sleep has limited impact on our metabolism, drinking coffee as a way to perk you up from a slumber can have a negative effect on blood glucose (sugar) control,” said study authors from the University of Bath in the UK.

During the study, the research team asked 29 healthy men and women to undergo three different overnight experiments in random order. In one, condition participants had a normal night’s sleep and were asked to consume a sugary drink on waking in the morning.

On another occasion, participants experienced a disrupted night’s sleep (where the researchers woke them every hour for five minutes) and then upon waking were given the same sugary drink.

On another, participants experienced the same sleep disruption but this time were first given a strong black coffee 30 minutes before consuming the sugary drink.In each of these tests, blood samples from participants were taken following the glucose drink which in energy content (calories) mirrored what might typically be consumed for breakfast.

Their findings highlight that one night of disrupted sleep did not worsen participants’ blood glucose/insulin responses at breakfast when compared to a normal night’s sleep.

Past research suggests that losing many hours of sleep over one and/or multiple nights can have negative metabolic effects, so it is reassuring to learn that a single night of fragmented sleep (e.g. due to insomnia, noise disturbance or a new baby) does not have the same effect. However, strong black coffee consumed before breakfast substantially increased the blood glucose response to breakfast by around 50 per cent.

This new study reveals that the common remedy of drinking coffee after a bad night’s sleep may solve the problem of feeling sleepy but could create another by limiting your body’s ability to tolerate the sugar in your breakfast.

“We know that nearly half of us will wake in the morning and, before doing anything else, drink coffee — intuitively the more tired we feel, the stronger the coffee,” the authors wrote.