Long naps tied to MASLD in type 2 diabetes

Clinical takeaway: Asking patients with type 2 diabetes about long daytime naps is a simple way to try to gauge fatty liver risk. The link is associative and preliminary, so treat it as a risk signal.

Fatty liver disease is common in type 2 diabetes patients, but clinicians lack a quick way to identify who is most likely to develop it. Standard risk tests require labs or imaging. Researchers asked whether something simpler, a patient's sleep habits, could flag that risk instead. The early answer points to daytime napping.

The study focused on MASLD (metabolic dysfunction-associated steatotic liver disease), formerly called nonalcoholic fatty liver disease, defined by excess liver fat plus a cardiometabolic risk factor. The 2023 update shifted the diagnosis from one of exclusion to one anchored on metabolic risk, such as type 2 diabetes.

Among the four sleep groups, the combination of poor nighttime sleep and long daytime naps carried the steepest risk: more than triple that of patients who slept well at night and napped briefly. But long naps tracked with higher risk even when nighttime sleep was good, which is what set napping apart as an independent signal.

Over a follow-up of just over three years, 379 new MASLD cases arose. The other three groups were all associated with higher risk than the good-sleep, short-nap reference group.

The researchers collected sleep questionnaires from 1,900 adults with type 2 diabetes, aged 18 to 85, between 2017 and 2024. They sorted patients into four groups by nighttime sleep quality and nap length: good sleep with short nap, good sleep with long nap, poor sleep with short nap, and poor sleep with long nap, using a 30-minute cutoff for long naps. Multivariate Cox regression linked these patterns to new MASLD. The findings were presented at ENDO 2026 and have not yet been peer reviewed.

"Our work suggests long naps independently increase the likelihood of MASLD in individuals with type 2 diabetes," said Xuejiang Gu, M.D., Ph.D., executive director of the Endocrinology Department at the First Affiliated Hospital of Wenzhou Medical University in Wenzhou, Zhejiang, China. "However, poor nocturnal sleep combined with long naps more than triples MASLD risk in this population."

Source: Gu X, et al. ENDO 2026. 2026 Jun 15. Long naps and risk of metabolic dysfunction-associated steatotic liver disease in type 2 diabetes