LONDON – Drinking more than three cups of coffee a day can double a person’s risk of developing diabetes, researchers have today warned.
Regularly drinking coffee can increase the risk of prediabetes – the early stage of type two diabetes – in those adults who metabolise caffeine slowly and suffer hypertension, scientists have found.
The Italian team studied 1,180 patients aged between 18 and 45, who suffered stage one hypertension – high blood pressure – but not diabetes.
They found of the coffee drinkers, 87 per cent drank one to three cups a day, while 13 per cent drank more.
The study found 42 per cent of participants were fast metabolisers of caffeine and 58 per cent were slow.
Over the course of six years, scientists diagnosed prediabetes in 24 per cent of patients.
Moderate coffee drinkers were found to have a 34 per cent increased risk of developing prediabetes and heavy caffeine addicts faced a 50 per cent heightened risk.
Yet the risk of prediabetes linked with coffee intake was increased only in slow caffeine metabolisers.
Dr Lucio Mos, from San Daniele Cardiology Hospital in Udine, north east Italy said: ‘Lifestyle factors are very important for the prognosis of young people with hypertension.
‘In a previous analysis of HARVEST (Hypertension and Ambulatory Recording Venetia Study) we found that coffee was a risk factor for the development of sustained hypertension and that the risk was modulated by the genetic background of the individual.
‘Slow metabolisers of caffeine were at increased risk of hypertension.
‘Our study shows that drinking coffee increases the risk of prediabetes in young adults with hypertension who are slow caffeine metabolisers.
‘The risk is even greater if these individuals are overweight or obese, and if they are heavy drinkers of coffee.
‘Slow caffeine metabolisers are exposed for a longer time to the detrimental effects of caffeine on glucose metabolism.
‘Thus, the effect of coffee on prediabetes depends on two factors, the amount of daily coffee intake and the individual’s genetic background.
‘Young-to-middle-age people with hypertension should be aware that coffee consumption may increase their risk of developing diabetes in later life.
‘Genotyping for the CYP1A2 gene polymorphism could help them to better know their risk.
‘The results of the HARVEST study suggest that in patients with hypertension, caffeinated coffee should be considered a dietary risk factor for prediabetes.
‘This risk applies especially to slow caffeine metabolisers and to patients who are overweight or obese.
‘Our findings contradict previous epidemiologic studies that have advocated coffee consumption as a means to lower the risk of type two diabetes mellitus.’