In a cohort study of 1,156 middle-aged and older Chinese adults, researchers found that inadequate sleep duration and later sleep onset were associated with increased glycemic variability.

According to their findings recently published in JAMA Network Open, the investigators analyzed data from the Guangzhou Nutrition and Health Study, a prospective cohort in Guangdong, China. Participants aged 46 to 83 self-reported sleep duration and onset timing at multiple study visits. Continuous glucose monitoring devices monitored glycemic metrics in relation to long-term sleep patterns over 14 consecutive days. The investigators then applied Huber robust regression models, adjusted for age, sex, BMI, education, income, lifestyle factors, and HbA1c levels. They also evaluated combined sleep duration and onset timing effects.

Led by Luqi Shen, PhD, of Westlake Laboratory of Life Sciences and Biomedicine in Hangzhou, China, the researchers identified four sleep duration trajectories: severe inadequate (up to 4.7 hours), moderate inadequate (6 hours to 5.5 hours), mild inadequate (7.2 hours to 6.8 hours), and adequate (8 hours to 8.4 hours). Two sleep onset timing groups were also noted: persistent early and persistent late.

Severe inadequate sleep was associated with a 2.87% increase in the coefficient of variation (CV) of blood glucose (95% confidence interval [CI] = 1.23%-4.5%) and a 0.06 mmol/L increase in mean of daily differences (MODD; 95% CI = 0.02-0.09 mmol/L). Late sleep onset correlated with a 1.18% increase in CV (95% CI = 0.36%-2.01%) and a 0.02 mmol/L rise in MODD (95% CI = 0.01-0.04 mmol/L). Participants with both inadequate sleep duration and late sleep onset had the highest glycemic variability.

The researchers also found an association between postmidnight sleep onset and increased measures of glycemic variability, which is supported by previous research and points to "the potential detrimental role of circadian rhythm misalignment on glycemic regulation." 

"These findings emphasize the importance of considering both sleep duration and timing for optimizing glycemic control in the general population," the researchers wrote. "While the joint association for glycemic dynamics has yet to be investigated, evidence links late sleep onset time and sleep duration with higher cardiometabolic risks. In the current study, we found that participants with this combined phenotype exhibited the greatest glycemic variability, suggesting that sleep onset time and duration could be promising factors in improving glucose metabolism...in the primary prevention of diabetes."

Study limitations included self-report of sleep habits rather than objective measures. Factors such as sleep apnea were not examined and other chronic sleep fluctuations could have been missed as a result of limited measurements with trajectory groups. The researchers suggested that future research includes larger and more age- and ethnically diverse populations to validate and generalize findings beyond middle-aged and elderly Chinese participants. 

No competing interests were reported.