HbA1c variability: Predictive marker for progression of diabetic retinopathy in type II diabetics
Upashana Patro, Sanjeevani AmbekarABSTRACT
Introduction:
Diabetes retinopathy (DR) is a common microvascular complication of diabetes and has been recognized as one of the most common and leading causes for visual impairment and blindness. As the mean hemoglobin A1c (HbA1c) level increases, the risk of microvascular complications in diabetics rises exponentially. Another factor related to hyperglycemia is the variability of glycemic control that includes both “glucose variability” and “HbA1c variability”. Glucose variability is associated with intra-day fluctuation of glycemia, especially postprandial hyperglycemia, which may eventually be reflected as HbA1c levels above the normal range. On the other hand, HbA1c variability, expressed as the intrapersonal standard deviation (SD) of several HbA1c measurements, is regarded as an index of long-term (90 days) glycemic variability. Mean HbA1c and HbA1c variability are both independently associated with DR development and progression. For every 1% increase in the SD of HbA1c, the hazard ratio of both DR development and progression increased by more than 100%.
Objectives:
To compare glycemic control with HbA1c variability. To study the prevalence of HbA1c variability in DR in type II diabetics. To analyze the association of HbA1c variability with progression and severity of diabetic retinopathy in type II diabetics.
Settings and Design:
Prospective observational study, conducted at a tertiary care hospital in western India, over a period of 18 months.
Subjects and Methods:
The study was performed in the Department of Ophthalmology at a tertiary care center on 100 patients, with evidence of diabetic retinopathy, between the age group of 40–80 years. Socio-demographics, clinical parameters, disease characteristics, and treatment methods for each subject were collected according to a standardized protocol. Dilated fundus examination and HbA1c measurements of every study subject were recorded for baseline findings and followed up after every 3 months for assessment of DR status and measurement of HbA1c.
Statistical Analysis Used:
Quantitative data is presented with the help of mean and SD. Comparison among the study groups is done with the help of an unpaired t-test, as per the results of the normality test. Qualitative data are presented with the help of a frequency and percentage table. Association among the study groups is assessed with the help of Student’s t-test and Chi-square test. P <0.05 is taken as significant.
Results:
Total variability over time: +1.324%. Greater inter-visit HbA 1 c variability is clearly associated with progression from nonproliferative diabetic retinopathy to sight-threatening proliferative diabetic retinopathy and DME.
Conclusions:
Each rise in HbA 1 c between visits aligns with a shift in fundus findings, confirming that variability – not just mean HbA 1 c – may drive retinopathy worsening. This supports using HbA 1 c variability as a prognostic indicator for DR progression in clinical monitoring.