1. HIGHER INCIDENCE OF TYPE 2
DIABETES AMONG WOMEN
WORKING NIGHT SHIFTS
A REVIEW

2. Researchers
• Das Indranil. MBBS, DIH, MPH (on-going)
University of Eastern Finland.
• Heikkinen Jarmo. Clinical Lecturer, University
of Eastern Finland.
• Järvelin-Pasanen Susanna. University Teacher,
University of Eastern Finland.

3. Introduction
Type 2 diabetes
• Insulin resistance
• Relative lack of Insulin
• Polyuria, polydipsia and
polyphagia
Night shift
• 24 x7 work schedules and
round the clock service
• Working schedules during
night hours
• Graveyard shift

4. Type 2 diabetes and melatonin
• Diurnal changes of insulin, related to circadian
rhythm and sleep
• The synchronization is linked to melatonin
• Risk related to genotype and lifestyle

5. Epidemiology
• Ice berg phenomenon
• In 2010, 285 million affected world wide
• Expected prevalence 4.4% by 2030
• Mostly a disease of urban obese population

6. Complications of type 2 diabetes
• Cardiovascular
complications
• Renal diseases
• Ophthalmic
complications
• Obstetric complications-
High Perinatal
mortality, Congenital
malformations, higher
incidence of operative
procedures.

7. Night Shift and Health
Complex interaction.
Circadian Rhythm disruption
Social disruption

8. Objectives
• Summarize the studies on incidence of type 2
diabetes among women working in night shifts
• Study the effect of number of years worked on
the risk of type 2 diabetes among women
working in night shifts

9. Importance of this study
• Less studies on women
• Women are at added risk
• Increasing participation of women 24X7 jobs

10. Selection of Studies

11. Result: Selected studies.
Study Design Study population Follow Up Exposure
assesment
Pan et al. 2011 Cohort study (NHS I) N= 69269
Age group: 42-67
years
18-20 yrs. Self-reported
T2DM confirmed
by validated
questionnaire.
Cohort study (NHS II) N=107915
Age group: 25-42
years
18-20 yrs. Self-reported
T2DM confirmed
by validated
questionnaire.
Kroenke et al. 2007 Cohort study (NHS II) N=62574 Age
group: 29-46 years.
6 yrs. Biennial mailed
questionnaire.
Supplementary
validated
questionnaire.

12. Result: Association & incidence
Study Nightshift Work Incidence Hazard Ratio (95% CI) Conclusion
Pan A et al. 2011 3 nights per month in
addition to day and
evening shift
6165 ( in NHS I)
3961 (in NHS II)
1.58 (1.43-1.74) (working
in night shift more than or
equal to 20 years)
Positive association.
Association mediated
by BMI
Kroenke CH et al.
2007
No
exclusion criteria
365 1.41 (0.96-2.06)
(working in night shift >10
years)
No association when
adjusted for BMI
(Obesity)

13. Result: Risk and number of years
worked(Pan et al. 2011)
Number of years worked in Night Shift Unadjusted Hazard Ratio (95% CI) Hazard Ratio after adjustment for BMI
1 -2 years 1.05 (1.00-1.11) 1.03 (0.98-1.08)
3- 9 years 1.20 (1.14-1.26) 1.06 (1.01-1.11)
10-19 years 1.40 (1.30-1.51) 1.10 (1.02-1.18)
More than 20 years 1.58 (1.43-1.74) 1.24 (1.13-1.37)

14. Conclusions
• Incidence of type 2 diabetes is higher among
women working in night shifts, BMI plays an
important role in the association. But more
studies are required to establish cause effect
relationship.
• Risk increases with the number of years
worked in night shift, significantly after 10
years of night shift working.

15. Recommendations
• Health education: diet, life style adjustments,
screening
• Occupational health facilities
• Pre employment, and regular health check up
• Research with different cohort, better case
identification and longer follow up

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