HbA1c cut-off identified for increased sight-threatening retinopathy risk
MedWire News: Having a glycated hemoglobin (HbA1c) value above 8.0% significantly increases the risk for sight-threatening retinopathy (STDR) in patients with diabetes, show Indian study findings.
Previous studies, such as the Early Treatment Diabetic Retinopathy Study, have shown that an elevated level of HbA1c is a strong predictor for proliferative retinopathy, but the level of HbA1c at which the risk for STDR increases significantly is unclear.
To investigate further, Tarun Sharma (Shri Bhagwan Mahavir Vitreoretinal Services, Chennai, Tamil Nadu) and colleagues evaluated the HbA1c level and retinopathy status of 1414 individuals with diabetes from the Chennai area of India, aged 57.3 years on average. Presence or absence of STDR (severe non-proliferative retinopathy, proliferative retinopathy, or diabetic macular edema) was assessed using fundus photographs.
The team found that 1159 participants had no retinopathy (controls). Of the 255 with retinopathy, 210 did not have STDR and 45 had STDR. Mean HbA1c was 7.9%, 9.2%, and 9.7% in the control, non-STDR, and STDR groups, respectively.
In addition to having higher HbA1c, those with STDR had a longer duration of diabetes, were more likely to be male, had a lower body mass index, and were more likely to have macro- or micro-albuminuria than controls. The non-STDR group with less severe retinopathy tended to be intermediate between the controls and the STDR patients for the above factors.
Using the receiver operating characteristic curve analysis, Gupta and co-workers found that a cut-off value of 8.0% for HbA1c was most predictive for both non-STDR and STDR. They recorded a 75.6% sensitivity and a 58.2% specificity with a 64.9% maximum area under the curve for this value.
"Targeted screening for retinopathy in subjects with diabetes with HbA1c greater than 8.0% would give maximum yield of sight-threatening retinopathies," suggest the authors.
The results of this study are published in the journal Diabetes Research and Clinical Practice.
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By Helen Albert