How shift work increases disease risk

Exhausted female nurse resting and yawning in hospital lobby

New research may have unearthed how shift work can have a long-term effect on the risk of heart disease and diabetes.

Previous studies have shown that shift work is associated with heart and metabolic diseases. A recent study published in Experimental Physiology suggests shift work has a negative impact on the way triglycerides are broken down and the way sugar is utilised in the body.

University of Delhi researchers studied two groups of healthcare workers. The first group included nurses, doctors and healthcare workers aged 20-40 years of both sexes who had not done night shift in the past one year or ever and had normal blood sugar levels. The second group was of the same professional background and age but were involved in rotational night shift duties (more than four nights per month at least for the past one year) and had normal blood sugar levels.

Blood sugar levels were measured using an oral glucose tolerance test. After 12 hours of overnight fasting, participants were given a high fat meal. Fasting insulin levels and triglyceride levels after fasting and after the meal, were measured in all study participants. These were compared between healthcare workers who had and had not undertaken rotational night shift.

Results showed a significant positive correlation with measures of insulin resistance (fasting insulin) only in healthcare workers working night shifts. This finding suggests possible development of insulin resistance among shift workers exposed to rotational night shifts which in turn results in altered metabolism, according to the researchers.

With over 20% of the population in industrial countries doing shift work, in sectors such as healthcare, there is an urgent need to understand its health burden, University College of Medical Sciences, University of Delhi and lead researcher Sri Venkata Madhu said.

“This study gives us a better understanding of why shift work is associated, in the long-term, with heart and metabolic diseases, helping us work towards reducing the incidence of heart disease, diabetes and obesity in the future.”

The open access paper is available at:


Kiranmala et al. 2019. “Association of postprandial triglyceride responses with insulin resistance among rotational night shift healthcare workers”, Experimental Physiology.

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