A new study reveals that individuals with a late chronotype—those who prefer to sleep and wake up later—are nearly 50% more likely to develop type 2 diabetes (T2D). This elevated risk is linked not only to unhealthy lifestyle factors, as previously thought, but also to circadian misalignment. Lead researcher Dr. Jeroen van der Velde suggests that late chronotypes’ internal body clocks may be out of sync with societal schedules, causing disruptions in metabolism. The study, involving over 5,000 participants, found that late chronotypes had higher BMI, larger waist circumference, and increased visceral and liver fat, all of which are key risk factors for T2D. MRI scans revealed late chronotypes had 7 cm² more visceral fat and 14% higher liver fat content. These findings emphasize the role of circadian rhythm disturbances in metabolic health, highlighting the need for further investigation into how sleep timing affects diabetes risk.
Recent research sheds light on the connection between sleep patterns and the risk of developing type 2 diabetes (T2D), revealing that individuals with a late chronotype—those who prefer to go to bed and wake up late—are nearly 50% more likely to develop the condition than those with earlier sleep schedules. This study, presented at the Annual Meeting of the European Association for the Study of Diabetes (EASD) in Madrid, Spain, delves into the mechanisms behind this increased risk, showing that the relationship between late chronotypes and diabetes cannot be attributed solely to lifestyle factors. The research also highlights the role of circadian misalignment, which may disrupt metabolic processes and contribute to the development of T2D.
Chronotype and Diabetes Risk
Chronotype refers to an individual’s natural preference for waking and sleeping times, which can be categorized into three groups: early chronotype (morning people), intermediate chronotype (neither strictly early nor late risers), and late chronotype (night owls). It is well-established that lifestyle factors such as poor diet, lack of physical activity, and insufficient sleep are risk factors for obesity and metabolic disorders, including T2D. However, recent findings indicate that even after controlling for these variables, late chronotypes face a significantly higher risk of developing the disease.
The new study, led by Dr. Jeroen van der Velde from Leiden University Medical Centre in the Netherlands, followed over 5,000 individuals divided into these three chronotype categories. The research team measured participants’ body mass index (BMI), waist circumference, and levels of visceral fat (fat surrounding internal organs) and liver fat using MRI scans and MR spectroscopy. After a follow-up period of approximately 6.6 years, the researchers observed that late chronotypes had a 46% higher risk of developing T2D compared to their intermediate and early counterparts. This increased risk remained significant even after accounting for lifestyle factors, suggesting that other mechanisms are at play.
Circadian Misalignment and Metabolic Health
One of the most compelling explanations for the increased diabetes risk among night owls is circadian misalignment. The body’s circadian rhythm is the internal clock that regulates various physiological processes, including sleep-wake cycles, hormone production, and metabolism. When an individual’s natural circadian rhythm is out of sync with societal demands—such as work schedules or social obligations—it can lead to circadian misalignment. This misalignment is particularly common among night owls, whose biological clocks may conflict with early-morning work or school schedules.
Dr. van der Velde explains that this misalignment can have detrimental effects on metabolic health. “Circadian rhythm disturbances have been shown to interfere with glucose metabolism, insulin sensitivity, and the regulation of hunger hormones,” he notes. These disturbances can lead to metabolic dysfunction, increasing the risk of developing T2D over time. Furthermore, the irregular sleep patterns associated with late chronotypes may contribute to chronic sleep deprivation, which has been linked to insulin resistance, inflammation, and impaired glucose tolerance—all key factors in the development of diabetes.
Body Fat Distribution and Diabetes Risk
Another critical finding of the study is the relationship between late chronotypes and body fat distribution. Individuals with a late chronotype were found to have a higher BMI, larger waist circumference, and greater amounts of visceral and liver fat compared to those with an early or intermediate chronotype. Specifically, night owls had a 0.7 kg/m² higher BMI, a 1.9 cm larger waist circumference, 7 cm² more visceral fat, and 14% more liver fat than intermediate chronotypes. Visceral fat, in particular, is strongly associated with metabolic disorders such as insulin resistance, cardiovascular disease, and T2D.
The accumulation of liver fat, or non-alcoholic fatty liver disease (NAFLD), is also a significant risk factor for diabetes. Excess fat in the liver impairs its ability to regulate blood sugar levels and contributes to insulin resistance, making individuals more susceptible to T2D. The study’s findings suggest that the increased visceral and liver fat among late chronotypes may be one of the driving factors behind their elevated diabetes risk.
Behavioral Factors and Lifestyle Choices
While the study indicates that circadian misalignment and fat distribution play a significant role in the increased diabetes risk among late chronotypes, lifestyle factors cannot be entirely discounted. Previous research has shown that night owls tend to have less healthy behaviors compared to early risers. For example, they are more likely to engage in sedentary activities, consume higher amounts of sugary and processed foods, and have irregular meal patterns, all of which contribute to obesity and metabolic dysfunction.
Late chronotypes are also more prone to consuming food late at night, which has been linked to poorer glucose regulation and weight gain. Studies suggest that eating late disrupts the body’s natural insulin response, leading to elevated blood sugar levels and an increased risk of diabetes. Additionally, night owls may be less likely to engage in regular physical activity, further exacerbating their risk for obesity and T2D.
Sleep quality and duration also play a crucial role in metabolic health. Night owls are more likely to experience disrupted or insufficient sleep due to their irregular sleep schedules, which can lead to chronic sleep deprivation. Poor sleep quality has been shown to impair glucose metabolism, increase hunger hormones like ghrelin, and decrease levels of leptin, a hormone responsible for regulating satiety. Over time, these factors can contribute to weight gain and insulin resistance, increasing the risk of T2D.
Implications for Public Health and Future Research
The findings of this study have significant implications for public health, particularly as the prevalence of T2D continues to rise globally. Understanding the role of chronotype in diabetes risk may help healthcare providers develop more targeted prevention strategies. For example, individuals with a late chronotype may benefit from interventions that focus on aligning their circadian rhythms with societal schedules, such as promoting earlier bedtimes, improving sleep hygiene, and encouraging regular physical activity.
Moreover, the study highlights the need for further research into the biological mechanisms linking circadian misalignment with metabolic health. While the current findings suggest that disruptions in the body’s internal clock may play a key role in the development of T2D, more research is needed to fully understand the underlying pathways. Future studies could explore interventions aimed at reducing circadian misalignment, such as light therapy, timed meals, and pharmacological treatments, and assess their impact on metabolic outcomes.
Conclusion
The study provides compelling evidence that individuals with a late chronotype are at a significantly higher risk of developing type 2 diabetes, largely due to circadian misalignment and differences in body fat distribution. While lifestyle factors such as diet, exercise, and sleep quality also contribute to this increased risk, the findings suggest that the internal body clock plays a critical role in regulating metabolic health. As diabetes rates continue to rise worldwide, these insights into the relationship between chronotype and metabolic disorders may help inform more effective prevention and treatment strategies tailored to individuals’ natural sleep-wake preferences.
