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.