Impact of metabolic control on macular thickness in diabetic macular oedema

PURPOSE: To investigate the impact of metabolic control on macular thickness measured using optical coherence tomography in patients with diabetic retinopathy with or without macular oedema. METHODS: A total of 124 patients with diabetic retinopathy (n = 70 without macular oedema and n = 54 with macular oedema) were enrolled. Optical coherence tomography parameters measured included central macular thickness and total macular volume. Metabolic factors with correlation to optical coherence tomography parameters were fasting plasma glucose, glycosylated haemoglobin, triglyceride, low-density lipoprotein and estimated glomerular filtration rate. Multiple linear regression models were used to evaluate associations between optical coherence tomography parameters and metabolic factors. RESULTS: Higher glycosylated haemoglobin values were correlated with increased central macular thickness in patients without macular oedema (R = 0.289, p = 0.015), whereas glycosylated haemoglobin values were inversely associated with central macular thickness in patients with macular oedema (R = –0.374, p = 0.005). Both were found to be statistically significant after adjusting for age, sex and diabetic retinopathy severity in addition to other metabolic factors (p = 0.009 and p = 0.002, respectively). CONCLUSION: Strict metabolic control may not be associated with better macular thickness in diabetic patients with co-existing macular oedema.