Long daytime naps over 30 minutes linked to higher risk of fatty liver disease in people with type 2 diabetes, new ENDO 2026 data suggest
CHICAGO — A study presented Tuesday at ENDO 2026, the Endocrine Society’s annual meeting, found that people with type 2 diabetes who took daytime naps longer than 30 minutes had a higher risk of metabolic dysfunction–associated steatotic liver disease. Researchers from Wenzhou Medical University in China said long naps appeared to independently increase the likelihood of fatty liver disease in this population.
The study, conducted by researchers at the First Affiliated Hospital of Wenzhou Medical University in Zhejiang, China, analyzed individuals with established type 2 diabetes to assess the relationship between daytime nap duration and the risk of metabolic dysfunction–associated steatotic liver disease (MASLD). According to lead author Xuejiang Gu, M.D., Ph.D., executive director of the hospital’s Endocrinology Department, naps longer than 30 minutes were independently linked to a higher likelihood of MASLD among people with type 2 diabetes, regardless of nighttime sleep quality. “Long naps appear to independently increase the likelihood of MASLD in people with type 2 diabetes,” Gu said during the presentation at ENDO 2026, held June 3–6 in Chicago.
“Naps longer than 30 minutes were independently linked to a higher likelihood of MASLD among people with type 2 diabetes, regardless of nighttime sleep quality.”
The association between prolonged daytime napping and fatty liver disease risk persisted even after adjusting for the quality of nocturnal sleep, suggesting that nap duration itself is a significant factor. Participants who napped for less than 30 minutes did not show a similar increased risk, according to the data presented. Moreover, the combination of poor nighttime sleep and long daytime naps more than tripled the risk of MASLD compared with individuals without these sleep disturbances, underscoring the combined impact of sleep quantity and quality on liver health in this population.
This finding aligns with previous research linking adverse sleep behaviors to metabolic fatty liver disease. Prior Endocrine Society reports have identified daytime napping exceeding 30 minutes, late bedtimes, and snoring as risk factors for metabolic-associated fatty liver disease (MAFLD). One large Chinese cohort study cited by the researchers found that these sleep behaviors were associated with increased odds of MAFLD, with an adjusted odds ratio of 1.17 for napping longer than 30 minutes. The presence of both prolonged daytime napping and disturbed nighttime sleep was associated with more than twice the odds of MAFLD, even after controlling for obesity and other confounders.
Supporting evidence from broader populations further substantiates the link between long daytime naps and fatty liver disease. A systematic review and meta-analysis of 13 observational studies involving 48,248 participants reported that daytime napping was associated with a higher incidence of nonalcoholic fatty liver disease (NAFLD) and MAFLD, with a pooled odds ratio of 1.13. Within that analysis, long naps were significantly associated with increased disease risk (odds ratio 1.21), while short naps showed no significant effect. Another meta-analysis and Mendelian randomization study found that naps exceeding 30 minutes were associated with a 32% increased risk of NAFLD compared with non-nappers. Observational data from Guangdong Province, China, similarly demonstrated that daytime napping of 60 minutes or more was positively associated with NAFLD, with an adjusted odds ratio of 2.21.
The overlap between diabetes, metabolic risk, and napping behavior is also well documented. A systematic review and meta-analysis of 40 studies found habitual daytime napping was linked to increased diabetes risk, with an odds ratio of 1.20, and poor glycemic control in people with diabetes, with an odds ratio of 2.05. Naps lasting less than 30 minutes were not associated with diabetes risk, whereas naps of 30 to 60 minutes and longer than 60 minutes were linked to progressively higher risks. A study published in Frontiers in Endocrinology reported that napping longer than 30 minutes increased type 2 diabetes risk by 8 to 21%, with combined non-optimal nighttime sleep and napping further elevating risk. A Spanish cohort of older adults at high cardiovascular risk found that longer daytime napping was associated with higher prevalence of type 2 diabetes and increased adiposity, reinforcing the connection between prolonged napping and adverse metabolic profiles.
Given that MASLD and fatty liver disease are closely tied to insulin resistance and metabolic dysfunction, these findings provide indirect support for the ENDO 2026 data indicating that people with type 2 diabetes who nap longer than 30 minutes are particularly vulnerable to fatty liver disease. The Endocrine Society has previously emphasized that poor sleep behaviors, including prolonged daytime napping, are risk factors for fatty liver disease. Their prior analyses showed that patients exhibiting both prolonged naps and nighttime sleep disturbances had more than double the odds of metabolic-associated fatty liver disease, even after adjusting for obesity and other variables.
The researchers and Endocrine Society officials have highlighted that sleep and napping patterns may serve as actionable risk markers in clinical practice. Routine assessment of nap duration and nighttime sleep quality could help identify patients with type 2 diabetes at higher risk for fatty liver disease. The investigators suggested that modifying nap habits may represent a simple behavioral strategy to reduce MASLD risk in this population.
The ENDO 2026 study adds to a growing body of evidence on the role of sleep behaviors in metabolic health, particularly among people with type 2 diabetes. Future research may further elucidate the mechanisms linking prolonged daytime napping and fatty liver disease, as well as the potential benefits of targeted sleep interventions in this high-risk group.
