Curvilinear associations of sleep patterns during weekdays and weekends with glycemic control in type 2 diabetes: the Hong Kong Diabetes Registry

The importance of sleep regularity: a consensus statement of the National Sleep Foundation sleep timing and variability panel

OBJECTIVE

To develop and present consensus findings of the National Sleep Foundation sleep timing and variability panel regarding the impact of sleep timing variability on health and performance.

METHODS

The National Sleep Foundation assembled a panel of sleep and circadian experts to evaluate the scientific evidence and conduct a formal consensus and voting procedure. A systematic literature review was conducted using the NIH National Library of Medicine PubMed database, and panelists voted on the appropriateness of 3 questions using a modified Delphi RAND/UCLA Appropriateness Method with 2 rounds of voting.

RESULTS

The literature search and panel review identified 63 full text publications to inform consensus voting. Panelists achieved consensus on each question: (1) is daily regularity in sleep timing important for (a) health or (b) performance? and (2) when sleep is of insufficient duration during the week (or work days), is catch-up sleep on weekends (or non-work days) important for health? Based on the evidence currently available, panelists agreed to an affirmative response to all 3 questions.

CONCLUSIONS

Consistency of sleep onset and offset timing is important for health, safety, and performance. Nonetheless, when insufficient sleep is obtained during the week/work days, weekend/non-work day catch-up sleep may be beneficial.

Gender and age differences in the association between sleep characteristics and fasting glucose levels in Chinese adults

AIM

The present study examined the associations between night-time sleep duration, midday napping duration and bedtime, and fasting glucose levels, and whether or not such associations are dependent on gender and age.

METHODS

This study was a cross-sectional analysis of 172,901 adults aged≥40 years living in mainland China. Sleep duration was obtained by self-reports of bedtime at night, waking-up time the next morning and average napping duration at midday. Fasting plasma glucose (FPG)≥7.0mmol/L was defined as hyperglycaemia. Independent associations between night-time sleep duration, midday naptime duration and bedtime with hyperglycaemia were evaluated using regression models.

RESULTS

Compared with night-time sleep durations of 6-7.9h, both short (<6h) and long (≥8h) night-time sleep durations were significantly associated with an increased risk of hyperglycaemia in women [odds ratio (OR): 1.12, 95% confidence interval (CI): 1.01-1.29 and OR: 1.14, 95% CI: 1.08-1.21, respectively], and revealed a U-shaped distribution of risk in women and no significant association in men. Long midday nap durations (≥1h) were significantly but weakly associated with hyperglycaemia (OR: 1.04, 95% CI: 1.01-1.09) compared with no napping without interactions from gender or age, whereas the association between bedtime and fasting glucose levels did vary according to gender and age.

CONCLUSION

Night-time sleep duration, midday napping duration and bedtime were all independently associated with the risk of hyperglycaemia, and some of the associations between these sleep characteristics and hyperglycaemia were gender- and age-dependent.

Intra-individual variability in sleep is related to glycaemic control in adults with type 2 diabetes

AIMS

To examine whether there were significant differences in sleep during weekdays/weekends and whether the intra-individual variability in sleep was related to glycaemic control in patients with type 2 diabetes.

DESIGN

Correlational, longitudinal design.

METHODS

Data were collected between February 2017-January 2018. In all, 56 adults with type 2 diabetes were included (60.7 years, 55.4% female). Sleep was measured using the Consensus Sleep Diary over 8 days. Intra-individual variability of sleep was calculated as the standard deviation of sleep variables. Standard deviations of sleep duration, sleep efficiency, sleep quality, and mid-sleep time were obtained. Glycaemic control was measured by haemoglobin A1C. Paired t test and multiple regression analysis were used.

RESULTS

Overall, there were no differences in sleep parameters between weekdays and weekends. Participants slept 20 min more over the weekends than during weekdays. The mid-sleep time during weekends was about 35 min later than during weekdays. Intra-individual variability of sleep duration and mid-sleep ranged from 27.6-167.4 min and 13-137 min, respectively. Controlling for covariates (e.g., distress, symptoms, and self-care), larger variability in sleep duration, and mid-sleep were significantly related to higher A1C levels.

CONCLUSION

Diabetes educators are recommended to include the assessment of intra-individual variability in sleep. Maintaining a regular sleep habit (e.g., sleep duration and sleep timing) should be highlighted during patient education.

IMPACT

Intra-individual variability in sleep is an alternative dimension for sleep assessment. This study examined whether intra-individual variability in sleep was related to glycaemic control in an older sample of type 2 diabetes patients using a sleep diary across 8 days. This sample had a similar sleep pattern during weekdays and weekends. Larger intra-individual variabilities in sleep duration and mid-sleep time were independently related to worse glycaemic control. Diabetes patients are recommended to maintain a regular sleep routine.

Gender differences in the associations between insomnia and glycemic control in patients with type 2 diabetes: a cross-sectional study

STUDY OBJECTIVES

Insomnia is associated with insulin resistance and type 2 diabetes (T2D) in the general population. However, the associations between insomnia and glycemic control in T2D population are not consistently reported. In this study, we aimed to examine the associations between insomnia and glycemic control, and gender differences in these associations among Hong Kong Chinese patients with T2D.

METHODS

This was a cross-sectional study involving T2D patients recruited from the Hong Kong Diabetes Registry between July 2010 and June 2015. Glycemic control was estimated by fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c). Participants with the Insomnia Severity Index score > 14 were considered as having insomnia.

RESULTS

A total of 3753 patients were recruited. Compared with patients without insomnia, patients with insomnia had higher levels of FPG and HbA1c. After adjustment for potential confounding factors, insomnia was associated with higher FPG and HbA1c in the entire cohort. There were significant interactions between insomnia and gender for FPG (p = 0.001) and HbA1c (p = 0.025) in the full model. Subgroup analyses found that men with insomnia had higher FPG [8.23 (7.85-8.61) mmol/L versus 7.50 (7.39-7.61) mmol/L, p < 0.001] and HbA1c [7.79 (7.57-8.02)% versus 7.45 (7.39-7.52)%, p = 0.005] than men without insomnia after adjusted for confounding factors, whereas such difference was not observed in women.

CONCLUSIONS

T2D patients with insomnia had worse glycemic control than the patients without insomnia. The associations were particularly pronounced in men.

Sleep duration and patterns in Chinese patients with diabetes: A meta-analysis of comparative studies and epidemiological surveys

PURPOSE

A meta-analysis on sleep duration and patterns in patients with diabetes in China.

DESIGN AND METHODS

Two investigators independently carried out a systematic literature search in both international and Chinese databases.

FINDINGS

A total of 47 studies with 98 911 patients were included. The pooled mean sleep duration was 7.15 hours/day in patients with diabetes and 7.49 hours/day in healthy controls. The estimated percentage of short sleep duration of less than 6 hours/day was 23.0% in patients with diabetes and 12.3% in healthy controls, while the proportion of short sleep duration of less than 7 hours/day was 38.0% in patients with diabetes and 14.1% in healthy controls.

PRACTICE IMPLICATIONS

Short sleep duration was common in Chinese patients with diabetes.

Sleep and Obesity

Rising global prevalence and incidence of obesity lead to increased cardiovascular-renal complications and cancers. Epidemiological studies reported a worldwide trend towards suboptimal sleep duration and poor sleep quality in parallel with this obesity epidemic. From rodents and human models, it is highly plausible that abnormalities in sleep, both quantity and quality, impact negatively on energy metabolism. While excess dietary intake and physical inactivity are the known drivers of the obesity epidemic, promotion of healthy sleep habits has emerged as a new target to combat obesity. In this light, present review focuses on the existing literature examining the relationship between sleep physiology and energy homeostasis. Notably, sleep dysregulation perturbs the metabolic milieu via alterations in hormones such as leptin and ghrelin, eating behavior, neuroendocrine and autonomic nervous systems. In addition, shift work and trans-meridian air travel may exert a negative influence on the hypothalamic-pituitary-adrenal axis and trigger circadian misalignment, leading to impaired glucose tolerance and increased fat accumulation. Amassing evidence has also suggested that uncoupling of the circadian clock can increase the risk of adverse metabolic health. Given the importance of sleep in maintaining energy homeostasis and that it is potentially modifiable, promoting good sleep hygiene may create new avenues for obesity prevention and treatment.