Associations between chronic glycosylated haemoglobin (HbA1c) level and macular volume in diabetes patients without macular oedema

Acta Ophthalmol. 2010: 88: 753–758 Abstract. Purpose:  This study aimed to examine the correlation between glycosylated haemoglobin (HbA1c) level and macular volume in diabetes patients without diabetic macular oedema (DMO). Methods:  We carried out an observational, cross-sectional study. Patients who had diabetes mellitus (DM) of ≥ 10 years duration without DMO were included. Only one eye of each patient was selected for analysis. Eyes with proliferative diabetic retinopathy were excluded. Central subfield thickness (CST), central subfield volume (CSV) and total macular volume (TMV) were measured by optical coherence tomography (OCT). Chronic HbA1c level was defined as the mean HbA1c value in the year prior to enrolment. Results:  We included 97 eyes from 97 patients (47 women, 50 men; mean age 62.2 years). They included eight type 1 and 89 type 2 DM patients. The mean duration of DM was 15.5 years. Forty-two (43%) eyes had no diabetic retinopathy and 55 (57%) eyes had non-proliferative diabetic retinopathy. In statistical analysis, CST (mean 188.80 ± 27.64 μm; r = 0.220, p = 0.030), CSV (mean 0.149 ± 0.021 mm3; r = 0.213, p = 0.036) and TMV (mean 6.497 ± 0.715 mm3; r = 0.299, p = 0.003) positively correlated with chronic HbA1c level (7.95 ± 1.29%). The linear regression model showed that chronic HbA1c level (standardized coefficient 0.253; p = 0.013) and age (standardized coefficient − 0.206; p = 0.040) were factors significantly related to TMV. Conclusions:  Chronic HbA1c level positively correlates with macular thickness and volume in patients with DM of ≥ 10 years duration without DMO. Our results suggest that subclinical macular volume and thickness changes may occur before DMO becomes clinically evident. Early tight glycaemic control prior to the onset of DMO may play an important role in preventing the deterioration of macular function by altering macular haemodynamics.