A research group led by Adjunct Assistant Professor Masako Furuya Tokoro, Associate Professor Tomoya Mita, and Professor and Chairman Hirotaka Watada of the Juntendo University Graduate School of Medicine announced on October 28 that people with type 2 diabetes who maintain a "night owl" rhythm (evening chronotype) tend to experience worsening blood glucose management and face an elevated risk of developing and progressing diabetic retinopathy. The researchers also found that being an evening chronotype itself is an independent risk factor. Improving evening lifestyle patterns may lead to the prevention of diabetic retinopathy and improvement in glucose metabolism for people with type 2 diabetes. Their findings were published in Diabetologia, the journal of the European Association for the Study of Diabetes on October 24.
Diabetic retinopathy is a chronic complication of diabetes in which high blood sugar causes damage to the small blood vessels of the retina and is considered one of the major causes of blindness. Improvement in blood glucose management has been reported to reduce this risk.
Chronotype refers to the characteristics of an individual's morning-evening lifestyle rhythm. It is known that evening-type individuals are exposed to light late at night, eat late, have low levels of physical activity, and have an increased risk of developing obesity and type 2 diabetes. Furthermore, even among those with type 2 diabetes, evening chronotypes tend to have higher HbA1c (hemoglobin A1c) levels, and caution is needed regarding worsening blood glucose management. In general, blood glucose management targeting less than 7% is recommended for the prevention of diabetic complications.
However, the long-term effects of chronotypes on blood glucose management and the development and progression of diabetic complications in people with type 2 diabetes have not been well understood.
Therefore, in this study, 731 people with type 2 diabetes who were attending Juntendo Hospital and other facilities and had no history of cardiovascular events were followed up for up to 10 years to investigate the relationship between lifestyle habits and the development and progression of diabetic retinopathy.
Evaluation items included diet, physical activity, sleep duration and quality, and lifestyle rhythm. Chronotype (evening-morning type) was determined using the MEQ (Morningness-Eveningness Questionnaire). The MEQ ranges from 16 to 86 points, with lower scores indicating evening-type tendencies and higher scores indicating morning-type tendencies.
The mean follow-up period was 7.5 years, and the development or progression of diabetic retinopathy was observed in 57 people (7.8%).
As a result, it was found that an evening chronotype was significantly associated with a higher risk of diabetic retinopathy even after adjusting for age, sex, and known risk factors. An evening chronotype had approximately twice the risk compared to an intermediate chronotype and a morning chronotype.
The evening chronotype group tended to be younger and have obesity tendencies with a shorter duration of diabetes but had higher HbA1c and triglyceride levels and lower HDL (good cholesterol) levels. They were characterized by poor sleep quality, high levels of depressive symptoms, short sleep duration, and low physical activity levels, with lifestyle habits such as late bedtimes and wake times, late mealtimes, frequent late-night snacks, and frequent breakfast skipping.
During the observation period, the evening chronotype group showed increases in HbA1c and insulin use rates.
Even in analyses that took into account blood glucose management status, being an evening chronotype itself was found to be associated with the risk of developing and progressing diabetic retinopathy and was an independent risk factor.
Mita commented: "Until now, diabetes patients with evening chronotypes have been given guidance to shift toward morning types from the perspective of weight gain and blood glucose management. In the future, we would like to examine what actual changes result from such interventions. There is a possibility that improving lifestyle rhythms will lead to the prevention of diabetic complications. We hope this will lead to treatment and prevention that are tailored to each patient's individual lifestyle habits."
Journal Information
Publication: Diabetologia
Title: An evening chronotype is associated with the incidence and progression of diabetic retinopathy in people with type 2 diabetes mellitus: a cohort study
DOI: 10.1007/s00125-025-06590-5
This article has been translated by JST with permission from The Science News Ltd. (https://sci-news.co.jp/). Unauthorized reproduction of the article and photographs is prohibited.