Nonalcoholic fatty liver disease, sleep behaviors, and incident type 2 diabetes

Objectives: Nonalcoholic fatty liver disease (NAFLD) is associated with incident type 2 diabetes; however, the extent to which NAFLD may confer its risk remains uncertain, especially in Europeans. Emerging evidence suggests that sleep behaviors are linked to NAFLD and diabetes. We aimed to measure whether sleep behaviors modified the association between NAFLD and incident type 2 diabetes.

Methods: This prospective cohort study included 362,834 participants without type 2 diabetes at baseline in UK Biobank data. Five sleep behaviors, including sleep duration, insomnia, snoring, chronotype, and daytime sleepiness, were collected from the questionnaire. Liver steatosis was based on the fatty liver index.

Results: During a median follow-up of 10.9 years, we documented 7,394 patients with incident type 2 diabetes. NAFLD was significantly associated with increased diabetes risk. Sleeping 7-8 h/day, no insomnia, no self-reported snoring and no frequent daytime sleepiness were independently associated with incident type 2 diabetes, with a 19%, 19%, 13%, and 29% lower risk, respectively. 33.8% and 33.5% of type 2 diabetes events in this cohort could be attributed to NAFLD and poor sleep pattern, respectively. We further found significant interaction between NAFLD and sleep duration and insomnia (P for interaction = 0.027 and 0.025, respectively). Compared those with NAFLD and abnormal sleep duration (≤6 h or ≥9 h) or insomnia, participants with non-NAFLD and normal sleep duration or non-insomnia had 57% (RR 0.43, 95% CI 0.40, 0.47) or 55% (RR 0.45, 95% CI 0.41, 0.50) lower risk of incident diabetes. These associations were independent of age, sex, ethnicity, education, family history, economic status, lifestyles, hemoglobin A1c, systolic blood pressure, total cholesterol, and associated medications.

Conclusion: Both NAFLD and some sleep behaviors were risk factors for type 2 diabetes. Insomnia and sleep duration modified the association between NAFLD and type 2 diabetes.