Enhancing Night and Day Circadian Contrast through Sleep Education in Prediabetes and Type 2 Diabetes Mellitus: A Randomized Controlled Trial.

Biology. 2022;11(6)
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Plain language summary

Diabetes mellitus is a chronic condition that occurs when blood glucose levels increase because the body cannot produce enough insulin or cannot effectively use the insulin it produces. Type 2 diabetes mellitus (T2DM) is the most common type of diabetes. It is a chronic metabolic disease that can be controlled when its pathophysiological factors are neutralised. The aim of this study was to analyse the effect of a sleep hygiene intervention in the management of impaired fasting glucose (IFG) and T2DM. This is an experimental study based on a parallel clinical trial using blocked randomization with equal allocation ratio. A total of 69 participants were included in the analysis (31 and 38 from the control and intervention groups, respectively). Results show a significant improvement in all the measured sleep parameters (sleep quality, time and efficiency). Furthermore, it also demonstrates that sleep health educational intervention, delivered during the regular check-ups of patients with T2DM or IFG, has a positive metabolic effect and is feasible as a complementary therapy in primary care settings. Authors conclude that sleep education improves T2DM metabolic management.

Expert Review

Conflicts of interest: None

Take Home Message:
  • Sleep has a restorative function that benefits glucose metabolism.
  • Sleep education should emphasise that maintaining a regular and sufficient sleep schedule and establishing a series of routines and habits in the hours prior to going to sleep would prevent early awakenings.
  • Education is an important part of clinical practice.

Evidence Category:
  • X A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
  • B: Systematic reviews including RCTs of limited number
  • C: Non-randomized trials, observational studies, narrative reviews
  • D: Case-reports, evidence-based clinical findings
  • E: Opinion piece, other

Summary Review:

The aim of this study was to analyse the effect of a sleep hygiene intervention in the management of impaired fasting glucose (IFG) or type 2 diabetes mellitus (T2DM).


This experimental parallel open-label clinical trial included 69 adults with IFG or T2DM.

The intervention was individual informative education which aimed to develop skills to improve sleep, which consisted of:

1. Information: Reading of the educational sheet (9 tips for a healthy sleep) with subsequent discussion.

2. Verification: checking participants understood the advice.

3. Participant information: One telephone call after 1 month was made as educational reinforcement of the intervention.

The controlled group received no educational intervention. The main outcome variable measured was levels of HbA1c (%) 3 and 6 months post intervention. Secondary outcomes were fasting glucose (mg/dL) 3 and 6 months post intervention, Pittsburgh Sleep Quality Index (PSQI), declared sleep hours and sleeping efficiency 3 months post intervention.


  • . 84.2% participants from the intervention group and 14.0% in the control group reported a change in sleep habits.
  • 3 months after the intervention, the control group did not report any change, while the intervention group reported a statistically significant improvement in all three: PSQI (−2.97 ± 2.93), hours of sleep (1.00 [0.00; 2.00] hours) and sleep efficiency (6.74 ± 12.9%).
  • The intervention group achieved a significant reduction in 3 months post intervention fasting glucose levels (−14.69; CI 95%: −28.15, −1.22) and HbA1c levels (−0.39; 95% CI: −0.73, −0.05), as well as a reduction in 6 months post intervention HbA1c levels (−0.66; 95% CI: −0.96, −0.36).


  • The results show a significant improvement in all the measured sleep parameters (sleep quality, time and efficiency).
  • The PSQI score improvement in the intervention group was 3.6 points higher than the control group.
  • The median sleep time in the intervention group was increased by 1.5 h, doubling the number of participants who reported sleeping more than 6 h.

Clinical practice applications:
  • An educational intervention in sleep hygiene and circadian contrast may help to increase sleep quality, time and efficiency.
  • The educational intervention helped lower HbA1c levels in patients with IFG and T2DM.
  • Sleep education helps to improve T2DM metabolic management.
  • The 9 tips for a healthy sleep, were developed from the latest guidelines from the American Academy of Sleep Medicine, the National Health Service, and the Health Department of Catalonia.

Considerations for future research:
  • The open-labelled intervention and the use of subjective variables related to sleep quality could lead to biassed self-reports in the intervention group so further studies are required.
  • Future studies should gather baseline parameters closer to the start of the intervention rather than wait 3 months to assess the immediate outcomes of the intervention.
  • Future research could take the same approach with diet and exercise education.


BACKGROUND Evidence supports a causal relationship between circadian disturbance and impaired glucose homeostasis. METHODS To determine the effect of an educational intervention delivered by primary care nurses to improve sleep hygiene, a parallel, open-label clinical trial in subjects aged 18 and older with impaired fasting glucose (IFG) or type 2 diabetes mellitus (T2DM) was performed. Study variables were sex, age, fasting glucose, glycated haemoglobin A1c (HbA1c), Pittsburgh Sleep Quality Index (PSQI), sleep duration and efficiency, body mass index, antidiabetic treatment, diet and physical exercise. An individual informative educational intervention was carried out following a bidirectional feedback method. The intervention aimed to develop skills to improve sleep through nine simple tips. An analysis of covariance was performed on all the mean centred outcome variables controlling for the respective baseline scores. RESULTS In the intervention group, PSQI dropped, the duration and quality of sleep increased, and a decrease in fasting glucose and in HbA1c levels was observed. CONCLUSION The proposed intervention is effective for improving sleep quality, length and efficiency, and for decreasing fasting glucose and HbA1c levels in only 3 months. These findings support the importance of sleep and circadian rhythm education focused on improving IFG and T2DM.

Lifestyle medicine

Fundamental Clinical Imbalances : Hormonal
Patient Centred Factors : Mediators/Diabetes mellitus
Environmental Inputs : Mind and spirit
Personal Lifestyle Factors : Sleep and relaxation
Functional Laboratory Testing : Blood

Methodological quality

Jadad score : 3
Allocation concealment : Yes
Publication Type : Journal Article