Late chronotype, or a tendency to go to sleep later, has been associated with an increased risk of type 2 diabetes, as well as higher adiposity. Previously, this risk was thought to be due to poorer lifestyle habits of individuals with late chronotype. However, new research presented at the Annual Meeting of the European Association for the Study of Diabetes has suggested that the link between late chronotype and type 2 diabetes is independent of lifestyle factors. Late chronotype is associated with a higher waist measurement, as well as higher amounts of fat on the waist and liver, but the reasons for this connection are still unclear and could be attributable to various factors.
Researchers from Leiden University Medical Center in the Netherlands presented their findings at the conference, showing an independent link between chronotype and type 2 diabetes in a cohort of 4,999 participants without type 2 diabetes. The study found that individuals with a late chronotype were at a 55% increased risk of developing type 2 diabetes over a 6-year follow-up period. They also had higher average BMI, larger waist circumference, and higher levels of visceral and liver fat compared to those with an intermediate chronotype. The relationship between type 2 diabetes and obesity was found to be independent of age, sex, education, physical activity, diet quality, alcohol intake, smoking, and sleep duration.
Lead researcher Jeroen van der Velde explained that the study results showed a more significant effect than expected, suggesting that lifestyle factors alone may not be sufficient to account for the differences in risk seen in late chronotypes. The study did not explore the reasons why late chronotype is associated with an increased risk of type 2 diabetes, but the authors suggest that circadian misalignment and meal timing may play a role. People with a late chronotype may experience metabolic disturbances due to their circadian rhythm being out of sync with societal norms, such as eating later in the evening and consuming less healthy snacks.
Our circadian rhythm governs our natural bodily functions over a 24-hour period, dictating when we wake up, eat, exercise, and sleep. There is natural variation in chronotypes between individuals, with some being early birds and others being night owls. However, societal conventions, such as work schedules, often cater to early chronotypes, leaving those with late chronotypes at a disadvantage. This misalignment with societal norms may contribute to negative health effects in late chronotypes, highlighting the importance of understanding and addressing these differences for better metabolic health.
