Blood sugar control does not necessarily prevent vision loss in diabetes

USA: Blood sugar control may not protect diabetes patients from vision loss as earlier believed, a recent study in the journal Investigative Ophthalmology and Visual Science has found. The results, however, do not deny the importance of tight blood sugar control in diabetic avoiding eye complications.

People with diabetes can have diabetic retinopathy when high blood sugar levels  over a period of time cause damage to blood vessels in the retina. 

The association between glycemic control and visual acuity may not be linear despite the good documentation of diabetes' ophthalmic sequelae. Previous studies have suggested that maintaining an HbA1c <7%. Previous studies have suggested that maintaining HbA1c <7% preserves visual acuity and controlling glycemic index may prevent the progression of diabetic retinopathy. Anjali Om, Emory University School of Medicine, Decatur, Georgia, United States, and colleagues performed a retrospective cohort analysis to determine how glycemic control in patients with proliferative diabetic retinopathy (PDR) or diabetic macular edema (DME) through a teleretina screening program affected the progression of visual acuity at subsequent follow-up appointments.

The researchers reviewed a total of 271 patients with proliferative diabetic retinopathy or diabetic macular edema with visual acuities tracked for each eye (total of 542 eyes). 

The cohort consisted of patients in the Grady Healthcare System screened via one of 13 diabetic teleretina screening cameras. For further evaluation, all pathological results were referred to the Grady Eye Clinic (GEC). Patients with PDR or DME were included in the study. Glycemic control was determined by subtracting patients' most recent HbA1C at the time of data collection from HbA1C at the time of presentation. Visual acuity was measured at the first GEC visit and at 1, 3, and 6-month follow-up visits. Change in visual acuity was calculated by subtracting patients' most recent visual acuity (in logMAR) from visual acuity at presentation. 

 "Even diligent glycemic control may not protect patients from declining visual acuity," wrote the authors. "Still the importance of tight glycemic control in avoiding diabetic eye complications cannot be denied. Rather, they suggest that there may be external factors that influence patients' progression after follow-up."

"Further research with larger sample sizes should focus on identifying variables with stronger predictive values. Additional efforts could be taken to identify barriers to follow up after initial teleretina screening," they concluded.

The study, "Effect of Glycemic Control on Visual Acuity in a Teleretinal Screening Program," is published in the journal Investigative Ophthalmology and Visual Science.