Interaction of Melatonin With MTNR1B Genotype on Glucose Control - Study 2

Interaction of Melatonin and Light With MTNR1B Genotype on Glucose Control - Study 2

This project aims to test the impact of melatonin and MTNR1B variation on regulation glucose regulation in a highly controlled in-laboratory setting and ex vivo in pancreatic islets.

The investigators' recent GWAS discovery of MTNR1B as a novel type 2 diabetes gene has sparked great interest into the role of melatonin in glycemic control, for which the mechanism is largely unknown. This research will determine the effect of melatonin and MTNR1B on glycemic control under highly-controlled, in-laboratory protocols while manipulating circulating melatonin concentrations (both up and down) and assessing glycemic control by frequently-sampled intravenous glucose tolerance tests, as well as in ex vivo human pancreatic islets. This research will provide mechanistic insights into the metabolic effects of melatonin and the MTNR1B risk variant and may help in evidence-based approaches and personalized recommendations to improve glycemic control in night shift workers and late-night eaters.

Inclusion Criteria:

• Body Mass Index: 20 and 35 kg/m2
• Age: 21-55 years of age
• Caucasian
• Non-smoking
• With regular sleep-wake cycle
• Passed medical and psychological screening tests

Exclusion Criteria:

• Acute, chronic or debilitating medical conditions
• History of neurological or psychiatric disorder
• History of sleep disorder or regular use of sleep-promoting medication
• Current prescription, herbal, or over-the-counter medication use
• Traveling across 2 or more time zones within past 3 months
• Worked night or rotating shift work within past 1 year
• Drug or alcohol dependency