A new study has shed new light on why people who carry a common genetic mutation may be more at risk for developing type 2 diabetes.

By carefully studying healthy subjects, researchers from Brigham and Women's Hospital (BWH) and the University of Murcia, Spain, were able to chart the effect of melatonin supplements on blood sugar control. Their results suggest that taking melatonin close to mealtimes may put people with a common genetic variant more at risk.

The work is the first to show that a person's genetic profile could impact their ability to tolerate glucose when they take melatonin, said co-corresponding author Frank Scheer.

The results suggest that people may need to exert caution when taking melatonin close to meal times, especially in carriers of the risk variant, said co-corresponding author Marta Garaulet.

The data suggest that when subjects take melatonin, the genetic risk variant in MTNR1B causes a much greater change in glucose tolerance in carriers compared to non-carriers, even in people who are not obese and not diabetic, said Scheer.

Scheer added that the results suggest that it may be important to take genetics into account when thinking about timing of food consumption and melatonin administration.

The team notes that further, large-scale studies will be needed in vulnerable populations before clinical recommendations can be made.

The study is reported in Metabolism.