Those who sleep and wake later have a higher BMI, more body fat and a near 50% higher chance of developing type 2 diabetes, says a new study.
A late chronotype, commonly known as a night owl, refers to someone who goes to bed and wakes up later. Researchers from the Leiden University Medical Centre noted that previous studies have found an association between late chronotypes and an unhealthy lifestyle. For example, they are more likely to smoke or have an unhealthy diet – both of which could be risk factors for diabetes.
However, the researchers said their findings suggest an increased risk of type 2 diabetes that is independent from other lifestyle factors.
Lead researcher Jeroen van der Velde said: ‘We believe that lifestyle cannot fully explain the relationship between a late chronotype and metabolic disorders.
‘In addition, while it is known that a late chronotype is associated with high BMI, it isn’t clear to what extent chronotype affects body fat distribution.’
Dr van der Velde’s team analysed the sleep patterns, body fat distribution and type 2 diabetes occurrence of 5,000 participants. Each participant filled out a questionnaire regarding their sleep habits, which was used to calculate their midpoint of sleep (MPS). The group was then divided into three segments: early, intermediate and late chronotype.
Participants were followed up for a median of 6.6 years. In this time, 225 were diagnosed with type 2 diabetes. Once adjusted for age, sex, education and lifestyle factors, the results showed that those with a late chronotype had a 46% greater chance of developing the disease.
Do lifestyle factors affect the increased diabetes risk?
According to the researchers, this suggests that increased diabetes risk in late chronotypes cannot be explained by lifestyle factors alone.
Dr van der Velde added: ‘We believe that other mechanisms are also at play. A likely explanation is that the circadian rhythm or body clock in late chronotypes is out of sync with the work and social schedules followed by society.
‘This can lead to circadian misalignment, which we know can lead to metabolic disturbances and ultimately type 2 diabetes.’
‘The next step is to study if those with a late chronotype improve in metabolic health when they make changes in the timing of their lifestyle habits.’
Jeroen van der Velde, Leiden University Medical Centre
Another possible explanation provided was the timing of meals in late chronotypes. Dr van der Velde said: ‘People with a late chronotype are probably more likely to eat until later in the evening.
‘While we did not measure this in our study, there is growing evidence that time-restricted eating, not eating anything after a certain time, such as 6pm, may lead to metabolic benefits.
‘Night owls who are concerned about the increased risk of type 2 diabetes might want to try this or, at least, try to refrain from eating late in the evening.’
The results also showed that late chronotypes had averagely 0.7kg/m2 higher BMI, 1.9cm larger waist circumference and 7cm2 more visceral fat.
Dr van der Velde concluded that the next step would be to ‘study if those with a late chronotype improve in metabolic health when they make changes in the timing of their lifestyle habits’.
Diabetes and steroids
Researchers from the University of Oxford have also identified use of steroids as a risk study for diabetes. Patients being treated with systemic glucocorticoids (steroids) were more than twice as likely to develop the condition.
The study included more than 450,000 patients admitted to the Oxford University Hospitals NHS Foundation Trust between 2013 and 2023. All were free from diabetes at the beginning of the trial and were not already taking steroids.
Those who were treated with steroids, including prednisolone, hydrocortisone and dexamethasone, were 2.6 times more likely to develop diabetes while in hospital. The researchers suggested that this link is due to steroids increasing patients’ blood sugar levels.
Study leader Rajna Golubic said: ‘These latest results give clinical staff a better estimate of how likely new diabetes is to occur and could prompt doctors to plan clinical care more effectively to detect and manage new diabetes.’
The study was prompted by the observation that previous analysis of the relationship between steroids and diabetes was based on much smaller samples. Dr Golubic said: ‘We wanted to expand the data to get a more accurate idea of how likely it is that people could develop diabetes while being treated with these drugs.’
Insulin resistance associated with 31 diseases
A further study has found that insulin resistance increases the risk of diabetes by 166%. In addition, researchers said that the condition increased the risk of developing 26 diseases in total. These include gout (61%), pancreatitis (31%), sleep disorders (18%) and bacterial infections (8%).
Jing Wu and a team from Cheeloo College of Medicine analysed data from more than 400,000 people to reach these findings. She said: ‘We have shown that by assessing the degree of insulin resistance, it is possible identify individuals who are at risk of developing obesity, hypertension, heart disease, gout, sciatica and some other diseases.
‘This provides a basis for early intervention measures to reduce the risk of disease and also offers new ideas for disease prevention and treatment.’
An association between insulin resistance and all-cause mortality was also identified. In females, every one-unit increase in insulin resistance was associated with an 11% higher risk of death.
‘Raising public awareness of these modifiable factors is important, as it empowers individuals to take proactive steps towards better metabolic health.’
Jing Wu, Cheeloo College of Medicine
Jing Wu stressed the importance of public awareness of lifestyle factors that can lead to insulin resistance. She said: ‘It empowers individuals to take proactive steps towards better metabolic health.
‘While we didn’t look at ways of improving insulin resistance, previous research has shown that lifestyle modifications, such as regular exercise and following a balanced diet low in added sugars and refined carbohydrates, can help reduce the risk of insulin resistance.’
Insulin resistance was also found to reduce the risk of a further five conditions. For example, Parkinson’s disease (-16%), osteoporosis (-13%) and anaemia (-6%). A total of 31 diseases were linked to insulin resistance in some way.
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