For Type 2 diabetes patients, the less time their glucose levels remain stable, the greater their chance of developing diabetic retinopathy, according to a new study published in Diabetes Care.

Chinese researchers investigated the association between diabetic retinopathy and “time in range”— the total proportion of time over a 24-hour period when blood sugar was within a healthy range of 3.9mmol/L to 10mmol/L. The study enrolled 3,262 patients who underwent continuous glucose monitoring for three days. The investigators also measured glycemic variability. 

Patients in the study had Type 2 diabetes for approximately eight years. The enrollees generally had poorly controlled diabetes with A1c test readings of at least 7.%, and their initial A1c readings, on average, were 8.9%.

The investigators found 24% of individuals in the study (780 people) had diabetic retinopathy. Additionally, individuals with the lowest percentage of time in range were most likely to have diabetic retinopathy. The study also found increased severity of eye damage was linked to less time in range.

Further adjustment of glycemic variability metrics partially weakened these associations, although the link between time in range and the presence of any diabetic retinopathy remained significant, researchers said.

Lu J, Ma X, Zhou J, et al. Association of time in range, as assessed by continuous glucose monitoring, with diabetic retinopathy in Type 2 diabetes. Diabetes Care. Sep 10, 2018 (E-pub, ahead of print).