NIOSH Training for Nurses on Shift Work and Long Work Hours
Diseases and Shift Work (Continued)
A growing number of studies link shift work with an increased risk for type 2 diabetes mellitus. The Harvard Nurses Study followed a group of women for 18 to 20 years and examined rotating night shifts (at least 3 nights per month) and risk for diabetes.71 As years on shift work increased, risk for diabetes increased in a dose-response manner: for 3 to 9 years of shift work, risk increased by 20%; for 10 to 19 years, risk increased by 40%; and for 20 or more years, by 58%. Their data suggest this was partially due to increased body mass index. Gan and colleagues conducted a meta-analysis of findings from 28 independent reports.72 Rotating schedules increased risk by 42%, which was higher than the other types of shift schedules. Night shift increased risk by 9%, whereas evening shifts did not show a significant relationship. Increase in risk from shift work differed by sex: men had a 37% increased risk, whereas women had a 9% increased risk. Monk and colleagues found that retirees whose shifts were fixed or rotating and overlapped midnight to 6 a.m. had double the risk of self-reported diabetes compared to former daytime workers.73
Rakshit et al. theorize that insufficient sleep and disruption to circadian rhythms increase the susceptibility of beta cells in the pancreas to damage and death.74 This leads to the development of diabetes.