MD Thesis Ultan Healy 17118051 FINAL APPROVED SIGNED.pdf (2.77 MB)
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A Case Control Study Exploring the Association Between Type 2 Diabetes Mellitus and Social Jetlag

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posted on 2022-03-21, 15:45 authored by Ultan Healy
The circadian system, a hierarchical network of oscillating molecular clocks which align behaviours to the external solar clock and synchronise complimentary physiological processes between disparate tissues, plays an important role in regulating metabolic processes relevant the pathogenesis of Type 2 Diabetes Mellitus. Disruption to the circadian system, in the form of rotating shift work, is a risk factor for developing metabolic disease including Type 2 Diabetes Mellitus and obesity. Superseding circadian preferred sleep-wake timing to meet social obligations such as employment or education represents a more subtle, but much more prevalent, form of circadian disruption. Such behaviour results in significantly different sleep-wake times on free days compared to non-free days; a phenomenon termed social jetlag. We hypothesise that social jetlag is a risk factor for Type 2 Diabetes Mellitus and as such will be more prevalent in subjects with Type 2 Diabetes Mellitus compared to matched normoglycaemic controls. To test this hypothesis, we completed a case control study exploring the association between diabetes and social jetlag/sleep timing variability. Metabolic parameters were examined by means of a 75g oral glucose tolerance test, social jetlag was determined by means of the Munich Chronotype Questionnaire, and objective sleep parameters were obtained by means of wrist-worn actigraphy. Here we report that subjects with Type 2 Diabetes Mellitus demonstrate an excess of social jetlag compared to age- and gender-matched normoglycaemic controls (0.96 hours vs 0.61 hours, p = 0.035), which remains significant after adjusting for BMI and other covariates. However, this observation was based on self-reported sleep times and was not associated with any difference in objective actigraphy measurements. Further studies will be needed to confirm this association, to assess for causality, and to determine if treatment strategies to mitigate circadian disruption are effective in treating or preventing metabolic disease.


First Supervisor

Prof John Hubert McDermott

Second Supervisor

Prof Seamus Sreenan

Third Supervisor

Prof Andrew Coogan


A thesis submitted for the degree of Doctor of Medicine from the Royal College of Surgeons in Ireland in 2021.

Published Citation

Healy, U., A Case Control Study Exploring the Association Between Type 2 Diabetes Mellitus and Social Jetlag [MD Thesis] Dublin: Royal College of Surgeons in Ireland; 2021

Degree Name

Doctor of Medicine (MD)

Date of award



  • Doctor of Medicine (MD)

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