Shift Work, Heredity, Insulin, and Food Timing Study

Study Overview
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Brief Summary
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The purpose of this study is to determine whether night time eating that coincides with elevated endogenous melatonin impairs glucose tolerance, particularly in carriers of the MTNR1B risk allele.

Detailed Description
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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.

Official Title
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Shift Work, Heredity, Insulin, and Food Timing (SHIFT) Study

Conditions
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Shift Work Type Circadian Rhythm Sleep Disorder, Diabetes Mellitus, Type 2, Circadian Rhythm Sleep Disorder, Shift Work Type, Insulin Resistance

Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Night Shift-Workers<br> | |
| Day Workers<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Area Under the Curve (AUC) glucose | Investigators will measure insulin and glucose levels for 120 minutes at day time and night time visits, and compare them by genotype at selected loci. | Between 0-120 minutes, Visit 2 and 3 | 
| Disposition index | Disposition index will be determined by frequently sampled oral glucose tolerance test | Between 0-120 minutes, Visit 2 and 3 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Corrected Insulin Response |  | Between 0-120 minutes, Visit 2 and 3 | 
| Insulin Sensitivity Index |  | Between 0-120 minutes, Visit 2 and 3 | 
| Fasting Glucose |  | Between 0-120 minutes, Visit 2 and 3 | 
| Fasting Insulin |  | Between 0-120 minutes, Visit 2 and 3 | 
| Plasma Melatonin |  | Between 0-120 minutes, Visit 2 and 3 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diabetes Mellitus, Type 2, Insulin Resistance, Shift Work, Circadian Rhythms, MTNR1B