Among high-altitude adults with T2DM, HbA1c exhibited a linear positive association with prevalent DR, with the association being strongest in those with low eGFR plus high BMI (OR 1.38, 95% CI 1.20–1.59).
The prevalence of diabetic retinopathy among adults with type 2 diabetes mellitus residing at high altitude was 26.6%.
Each 1% increase in HbA1c was independently associated with 19% higher odds of prevalent diabetic retinopathy after full adjustment.
Altitude group did not significantly modify the association between HbA1c and diabetic retinopathy.
Estimated glomerular filtration rate (eGFR) significantly modified the association between HbA1c and diabetic retinopathy.
Body mass index (BMI) showed a borderline modifying effect on the association between HbA1c and diabetic retinopathy.
The combination of low eGFR and high BMI was associated with the strongest HbA1c–DR relationship.
The study design was a retrospective, hospital-based, cross-sectional study of 1040 adults with type 2 diabetes mellitus at high altitude.
This research examined whether blood sugar control — measured by HbA1c, a standard marker reflecting average blood glucose over several months — is linked to diabetic eye disease (diabetic retinopathy) in people with type 2 diabetes who live at high altitudes in Qinghai Province, China. Among the 1,040 participants studied, about one in four (26.6%) had diabetic retinopathy. The study found that for every 1% rise in HbA1c, the likelihood of having diabetic retinopathy increased by approximately 19%, and this relationship was consistent and linear — meaning there was no threshold below which higher HbA1c stopped mattering. Importantly, the study also found that kidney function and body weight appeared to amplify this relationship. People with lower kidney filtration rates (indicating poorer kidney function) and those with higher BMI showed a stronger link between blood sugar levels and eye disease. In people with both low kidney function and high BMI, the odds of retinopathy rose by 38% for each 1% increase in HbA1c. Altitude itself (comparing those living at 1,800–2,500 meters versus above 2,500 meters) did not appear to change the strength of the HbA1c–retinopathy relationship. This research suggests that in high-altitude populations with type 2 diabetes, glycemic control alone may not fully capture retinopathy risk — kidney health and weight status may also need to be considered together when evaluating who is most at risk for diabetic eye disease. Because the study was cross-sectional (a snapshot in time), it cannot establish that high HbA1c causes retinopathy, and the BMI interaction finding is described by the authors as exploratory and requiring further confirmation.
Chen Y, Zhang B, Liu Y, Wang H, Tong L, Xi G, et al.. (2026). Association between glycated hemoglobin A1c and diabetic retinopathy in adults with type 2 diabetes mellitus residing at high altitudes.. Frontiers in endocrinology. https://doi.org/10.3389/fendo.2026.1889928