Black women working night shifts have an increased risk of developing diabetes

http://www.eurekalert.org/pub_releases/2015-01/d-bww010715.php

Public Release: 11-Jan-2015
Diabetologia

Data from a large ongoing study into the health of African-American women show that those who work night shifts are significantly more likely to develop diabetes than those who have never worked night shifts, with more years working the night shift resulting in a higher risk. Furthermore, the increased risk of diabetes seen in shift workers was more pronounced in younger women than older women.

•••••

Relative to never having worked the night shift, the increased risk of developing diabetes was 17% for 1-2 years night shift work; 23% for 3-9 years, and 42% for 10 or more years. After adjustment for BMI and lifestyle factors such as diet and smoking status, the association between increasing years of night shift work and increasing diabetes risk remained statistically significant, with a 23% increase in those who had worked night shifts for 10 years or more versus those who never had worked the night shift.

When black women having ever worked the night shift (any duration) were compared to those who had never worked it, they were found to be at a 22% increased risk of developing diabetes. After adjustment for BMI and lifestyle factors, this increased risk became 12%.

The authors also found that the association was stronger in younger women than in older women. Working night shifts for 10 or more years relative to never working the night shift was associated with a 39% higher risk of diabetes among women aged less than 50 years compared with 17% higher risk in women aged 50 years or over.

•••••

Shift work is associated with disrupted circadian rhythms and reduced total duration of sleep. Similar to the effects of jet lag, which are short term, shift workers experience fatigue, sleepiness during scheduled awake periods and poor sleep during scheduled sleep periods. These alterations in the normal sleep-wake cycle have profound effects on metabolism... Even after many years of night-shift work, circadian rhythms do not fully adjust to the shifted sleep-wake cycle. The metabolic effects of long-term shift work likely underlie a part of the association with diabetes that we and others describe and that strengthens with years of exposure to sleep disruption."

•••••

In view of the high prevalence of shift work among workers in the USA - 35% among non-Hispanic blacks and 28% in non-Hispanic whites - an increased diabetes risk among this group has important public health implications. There is a need for continued research into facilitating circadian adaptation to shift work and consideration of avoiding shift work in favour of other work arrangements when possible."