Lifestyle factors such as unhealthy eating, sedentary behaviour and smoking are important factors in in suboptimal diabetes outcomes. Underexposed lifestyle factors in this context are sleep and circadian rhythm. Sleep is a complex phenomenon, but most studies on sleep have so far focused on duration, quality and sleep timing. The latter is important as it functions as a cue for circadian rhythms, which are the physical, mental and behavioural changes that follow a 24-hour cycle, mainly responding to light and dark. ‘Circadian misalignment’ (e.g. ‘social jetlag’) is the term for asynchrony between the physical (endogenous) and behavioural sleep-wake cycles, for a large part due to the 24/7 access to light (not to mention the myriad screens to which people are exposed, e.g. mobile phones, computer screens, tablets etc.). This review, co-authored by Diabeter psychologist Giesje Nefs, aimed to investigate the roles and possible mechanisms of sleep and circadian rhythm disturbances in the development and outcomes of T1D and T2D and to identify current treatment options.

PubMed was searched from inception to August 2022, using search terms relating to diabetes, sleep and health outcomes. English or Dutch language, observational, experimental, interventional and review studies were included.

Key findings (related to T1D):

• There is limited evidence for a role of (maternal) sleep (duration or quality) and/or circadian disturbance in the development of T1D
• A large proportion of children <5 years with T1D are not meeting the recommended sleeping time (10-13 hours)
• People with T1D have shorter sleeping times and lower sleep quality than people without diabetes
• There seems to be an inverse relationship between sleep duration/quality and HbA1c
• Low sleep quality was reported to be related to higher prevalence of diabetic retinopathy
• Social jetlag was age-dependent among adults with T1D (adolescents, young adults and adults: 2.5, 1.6 and 0.9 hours, respectively)
• Circadian disturbance (e.g. shift work, social jetlag and sleep variability) was reported to be associated with higher HbA1c in people with T1D
• In terms of treatment the American Academy of Sleep Medicine advocates behavioural approaches (e.g. cognitive behavioural therapy [CBT], sleep extension), because of the addictive nature of medication
• In addition to improving glycemic outcomes, algorithm-driven insulin delivery may also improve sleep
• With respect to mechanisms there seems to be a bidirectional relationship between sleep/circadian rhythm disturbances and diabetes:
  • Irregularities in sleep/circadian rhythms disturb diabetes outcomes through biological mechanisms and indirectly via sub-optimal care
  • Disturbed diabetes outcomes lead to increased irregularities in sleep/circadian rhythms

Concluding, the authors state

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