Background: Melatonin is a neurohormone that regulates the circadian rhythm by translating photoperiodic information from the eyes to the brain. MTNR1B , is one of melatonin receptors which is expressed in the retina, in the brain and in pancreatic tissue. In Genome Wide Association studies a SNP in the intronic variant in MTNR1B was found to be to in association with elevated fasting plasma glucose and with increased risk of T2DM among lean and obese adults and children.