Shift Work, Heredity, Insulin, and Food Timing Study

Preliminary observations suggest that food intake coincident with high melatonin levels leads to impaired glucose tolerance-particularly in MTNR1B risk allele carriers. Our objectives are to determine the effect of concurrent food intake and melatonin on glucose tolerance; and to assess the role of MTNR1B single nucleotide polymorphism (SNP)*melatonin interaction in this deleterious effect. Our central hypothesis is that concurrent high melatonin levels and food intake, commonly experienced in night shift workers, cause long-term impairment of glucose tolerance and that this effect is worse in carriers of the MTNR1B type 2 diabetes (T2D) risk SNP than in non-carriers. The results of this proposal will help to clarify an ongoing controversy about the role of melatonin in glucose tolerance, and will help to develop novel strategies in the prevention and treatment of T2D, especially in shift workers, night eaters, and MTNR1B risk allele carriers.

Inclusion criteria

• Male or non-pregnant female
• 18-60 years
• Currently employed (night shift workers and day workers), graduate students, part-time workers, or unemployed
• Able and willing to give consent relevant to genetic investigation

Exclusion criteria

• Currently taking any medications for the treatment of diabetes
• Currently taking medications known to affect glycemic parameters, such as glucocorticoids, growth hormone or fluoroquinolones
• Pregnant, nursing or at risk of becoming pregnant
• Chronic renal failure, hepatic diseases, or cancer diagnoses
• Bulimia diagnosis, prone to binge eating
• Eating disorder diagnosis such as anorexia, binge eating, or bulimia
• With psychiatric illness, such as schizophrenia or bipolar affective disorder
• Blind
• History of bariatric surgery