NIOSH Training for Nurses on Shift Work and Long Work Hours

Diseases and Shift Work (Continued)

Diabetes Mellitus

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.