Daily Dose: "Night Owls" Less Healthy, at Higher Risk for T2D

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Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

Early this week we reported on a study published in the Annals of Internal Medicine that investigated the mediating role that modifiable lifestyle factors may play in the association between chronotype and risk for type 2 diabetes (T2D). Authors cited previous findings of an association between irregular sleep and higher risk for developing both T2D and cardiovsacular disease (CVD).

The study

Using data from the Nurses Health Study (NHS) 2 between 2009 and 2017 invesigators identified 63 676 women without history of CVD, cancer, or diabetes and separated them into groups having either a definite morning or definite evening chronotype. Lifestlye behaviors selected for measurement were diet quality, physical activity, alcohol intake, body mass index (BMI), smoking, and sleep duration. Incident T2D during the follow-up period was self-reported.

Findings

Approximately 35% of the cohort had a defininte morning chronotype and 11% a definite evening chronotype. The latter group had a more than 50% greater risk of having an unhealthy lifestyle vs the former. The risk of T2D among the "night owls" was 72% greater than among participants in the morning chronotype group--and that was after adjusting for sociodemographic factors, shift work, and family history. The risk for T2D remained higher in the evening chronotype group after adjustment for addtional lifestyle factors and after adjusting for all the measured factors with potential mediating role, the increased risk, while smaller, remained positive at 19%.

Authors' comment

“When we controlled for unhealthy lifestyle behaviors, the strong association between chronotype and diabetes risk was reduced but still remained, which means that lifestyle factors explain a notable proportion of this association," authors wrote. “If we are able to determine a causal link between chronotype and diabetes or other diseases, physicians could better tailor prevention strategies for their patients."

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