OBJECTIVETo explore the effects related to quality and duration of sleep and their interactions on the prevalence of type-2 diabetes (T2DM).

METHODS9 622 people aged 18 years and over were recruited for our cross-sectional study during March 2013 to May 2013. Unconditional logistic regression was used to analyze the relationship between quality and duration of sleep on T2DM. Bootstrap was used to calculate the relative excess risk of interaction (RERI), the attributable proportion (AP) of interaction and the synergy index (SI). 95% confidence intervals (CI) of RERI, AP and SI were estimated.

RESULTSConcerning the comparison between cases and controls on both individual and total scores, other scores were all significantly different (P < 0.01), except for two items (time for falling asleep and drugs for hypnosis). The prevalence of T2DM in volunteers with poor sleeping quality was higher than that in volunteers with good sleeping quality (P < 0.01). Individuals with sleep duration <6 hours had a higher prevalence of T2DM, when compared with individuals with sleep duration of 6-8 hours (P < 0.01). After adjusting for age, gender, level of education, occupation, family history of diabetes, status on cigarette smoking, alcohol intake, physical activities and body mass index (BMI), the prevalence of T2DM appeared the highest in those with poor sleeping quality and short duration (OR = 4.78, 95% CI:3.32-6.99; P < 0.01), when compared with those who had good sleep quality and 6-8 h sleep duration. The risk of T2DM still increased in people who had poor sleep or long duration (OR = 1.92, 95% CI:1.18-3.31; P < 0.01). Values of RERI, AP and SI (with 95% CI) were 2.33 (1.23-8.79), 0.67(0.21-0.83) and 6.87 (2.33-10.75), respectively, for the interaction between poor sleep quality and short sleep duration, while 0.33 (-0.12-1.13), 0.17 (-0.03-0.51), 1.56 (0.76-2.74) for the interaction between good sleep quality and long sleep duration.

CONCLUSIONOur results suggested that there were additive interactions between poor quality and shorter duration of sleep.