Women who work irregular hours may be at increased risk of developing type 2 diabetes, a major new study suggests.
US research on two large cohorts of women showed those who worked a rotating schedule including three or more night shifts per month, in addition to day and evening working hours, were at higher risk of developing the disease.
It also found extended years of rotating night shift work was associated with weight gain, which could increase risk.
Researchers from the Harvard School of Public Health followed 69,269 women aged 42 to 67 and 107,915 women aged 25 to 92 without diabetes, cardiovascular disease and cancer at baseline.
They documented 6,165 and 3,961 type 2 diabetes cases in each cohort respectively during 18 to 20 years of follow-up.
Compared with women who did no shift work, the pooled hazard ratios for participants with 1–2, 3–9, 10–19, and ?20 years of shift work were 1.05, 1.20 , 1.40, and 1.58 respectively.
Lead researcher Professor Frank Hu, professor of nutrition and epidemiology at the Channing Laboratory at Harvard Medical School, said: ‘An extended period of rotating night shift work is associated with a modestly increased risk of type 2 diabetes in women, which appears to be partly mediated through body weight.’
‘Proper screening and intervention strategies in rotating night shift workers are needed for prevention of diabetes.’