24th February 2026, A/Prof Chee L Khoo
We know that suboptimal glucose control is very associated with the incidence and progression of diabetic retinopathy. The duration of diabetes, high systolic BP, smoking, lack of exercise, poor diet and depression are the other risk factors which increase the incidence of diabetic retinopathy as well as the progression of retinopathy. Sleep disorders, which are commonly observed in people with type 2 diabetes (T2D), are also significant factors that influence the development of diabetic complications [1]. Sleep deprivation worsens insulin resistance and increases inflammation [2], which may exacerbate diabetic complications. Another sleep “disorder” is the disturbance in the circadian rhythm.
People with an evening chronotype may be more likely to experience a circadian misalignment. We saw that the evening chronotype is associated with higher risk of cardiovascular disease (CVD) in this fortnight’s issue of GPVoice. The effects of circadian rhythm misalignment on people without diabetes may be different in people with diabetes. People who have T2D already have impaired insulin secretion and severe insulin resistance and further aggravation of insulin secretion and resistance put them at higher risk of microvascular complications.
Indeed, Tokoro MF et al assessed the impact of lifestyle differences, particularly chronotype differences, on the incidence and progression of diabetic retinopathy, and their effects on long-term blood glucose management (3). This was a prospective observational trial. 731 Japanese outpatients with T2D and no apparent history of CVD. Lifestyle habits were assessed using questionnaires, including the Morningness–Eveningness Questionnaire (MEQ), to determine chronotype at baseline and at years 2 and/or 5.
The composite endpoint of this study was the incidence and progression of diabetic retinopathy.
At baseline:
Participants were divided into three groups based on their mean MEQ scores: ‘more evening’ chronotype, ‘neither’ and ‘more morning’ chronotype groups. Participants of the more evening chronotype group tended to be young and obese, had a shorter duration of diabetes, and had higher levels of HbA1c, triglycerides and eGFR and lower levels of HDL-cholesterol than those with the more morning chronotype at baseline. Participants in the more evening chronotype group tended to have shorter sleep duration and lower physical activity levels compared with those in the more morning chronotype group. They were likely to go to bed late, wake up late, have a late dinner and breakfast, frequently have late evening snacks, and less frequently have breakfast.
62.9% were men, the mean BMI was 24.6 kg/m2, the mean systolic BP was 126.6 mmHg, the median estimated duration of diabetes was 8.0 years, and the HbA1c was 6.96%. At baseline, 36.7% of the participants had various stages of diabetic retinopathy.
Results
During the median follow-up period of 7.56 years, 57 (7.8%) participants experienced the composite endpoint. The ‘more evening’ chronotype group had a 2.29-fold higher risk of the composite endpoint compared with the ‘neither’ group. Compared with the ‘more morning’ chronotype group, the more evening chronotype group had a 2.09-fold higher risk of the composite endpoint. Participants with the more evening chronotype experienced worsening glucose management over time compared with those with other chronotypes. However, a significant negative association between the mean MEQ scores and the composite endpoint was still observed after adjusting for the mean HbA1c levels over time. The proportion of participants using insulin use tended to increase more in the evening chronotype group than in other groups.
Summary
This study highlighted the importance of chronotype on the incidence and progression of diabetic retinopathy independent of HbA1c. Baseline prevalence of diabetic retinopathy in this study was 36.7%. This is consistent with the results of a meta-analysis showing that 35.4% of people with type 2 diabetes had diabetic retinopathy [3]. 1 in 3 of our patients will have retinopathy which is potentially sight threatening in many of those patients.
In addition to ensuring that their glucose control is optimal and other risk factors are controlled, enquire about sleep adequacy and chronotype.
References:
- Li B, Zhou C, Gu C et al (2024) Modifiable lifestyle, mental health status and diabetic retinopathy in U.S. adults aged 18–64 years with diabetes: a population-based cross-sectional study from NHANES to 1999–2018. BMC Public Health 24(1):11.
- Buxton OM, Pavlova M, Reid EW, Wang W, Simonson DC, Adler GK (2010) Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes 59(9):2126–2133
- Tokoro MF, Mita T, Osonoi Y, Someya Y, Osonoi T, Saito M, Nakayama S, Ishida H, Ishii R, Gosho M, Watada H. An evening chronotype is associated with the incidence and progression of diabetic retinopathy in people with type 2 diabetes mellitus: a cohort study. Diabetologia. 2026 Feb;69(2):504-514.
- Yau JW, Rogers SL, Kawasaki R et al (2012) Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care 35(3):556–564