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Genetics and timing of evening meals linked to greater risk of developing type 2 diabetes, experts say

Eating close to bedtime impacts on blood sugar levels in those already at risk of developing type 2 diabetes, a study has shown.

People with a genetic variant in the melatonin receptor MTNR1B have a greater risk of developing the condition. The combination of high levels of the hormone melatonin at bedtime and eating late at night has been shown to disrupt blood sugar levels in those with a genetic risk.

Melatonin, which is generally released at night, plays a vital role in sleep-wake cycles. The hormone, along with how closely food is consumed before sleeping, affects blood sugar control.

A team from Massachusetts General Hospital, Brigham and Women’s Hospital and the University of Murcia in Spain set out to explore the links.

The study included 845 adults from Spain, with participants fasting for eight hours and then over the course of two days, consuming an earlier meal and then a later meal. The researchers looked at the differences between people who were carriers or not carriers of the genetic variant in the melatonin receptor.

The team found that levels of melatonin levels were more than three times higher following the late dinner. Eating later was also found to result in lower insulin levels and higher blood sugar levels.

Those with the genetic variant had higher blood sugar levels in comparison with those without the variant following the later eating.

Lead author Professor Marta Garaulet, from the University of Murcia, said: “We found that late eating disturbed blood sugar control in the whole group. Furthermore, this impaired glucose control was predominantly seen in genetic risk variant carriers, representing about half of the cohort.”

Co-senior author Dr Frank A.J.L. Scheer added: “Our study results may be important in the effort towards prevention of type 2 diabetes. Our findings are applicable to about a third of the population in the industrialised world who consume food close to bedtime, as well as other populations who eat at night, including shift workers, or those experiencing jetlag or night eating disorders, as well as those who routinely use melatonin supplements close to food intake.”

The study authors advised that for the general population would benefit from not eating for at least two hours before bedtime.

The study has been published in Diabetes Care.

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