Urinary albumin excretion rate: a risk factor for retinal hard exudates in macular region in type 2 diabetic patients

Background The various risk factors for retinal hard exudates are still poorly understood in type 2 diabetic patients. The aim of this study was to determine the association between urinary albumin excretion rate (UAER) and hard exudates in macular region in north Chinese patients.

Methods A total of 272 patients (272 eyes) were enrolled for this study, including 154 subjects from group 1 (mild hard exudates), 91 subjects from group 2 (moderate hard exudates) and 27 subjects from group 3 (severe hard exudates) confirmed using colour fundus photography, optical coherence tomography (OCT) as well as slit-lamp biomicroscopy with 78 diopter (D) lens. Each participant underwent a comprehensive assessment that included biochemical, clinical characteristics test and detailed ophthalmic evaluation. One-way analysis of variance (ANOVA) test and chi-square test were performed to analyze the fasting blood glucose (FBG), glycated hemoglobin (HbA1c), total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TG), full blood counts, urinary albumin excretion rate (UAER), blood creatinine (CREA), duration of diabetes, body mass index (BMI), systolic blood pressures (SBP) and diastolic blood pressures (DBP) between groups. Ordinal logistic regression analysis was further performed in order to eliminating the possible confounding factors.

Results Three groups were matched in terms of age and gender. Risk factors which showed significant difference between groups include FBG (P <0.001), HbA1c (P <0.001), LDL (P <0.001), UAER (P <0.001), duration of diabetes (P=0.001), TC (P=0.005), SBP (P=0.026), CREA (P=0.004) and haemoglobin (Hb) (P=0.012). There was no significant difference between groups for the TG, HDL, DBP, platelet, total white blood cells and BMI. Using ordinal Logistic regression analyses, of all the variables, HbA1c, LDL and UAER which were independent risk factor for hard exudates showed a significantly odds ratio of 1.25, 3.07, and 1.39, respectively. There were also significant differences in UAER level between patients with mild, moderate, severe hard exudates groups (P <0.001).

Conclusions UAER was an independent risk factor associated with retinal hard exudates in macular region in type 2 diabetic patients. This study highlights the need for close monitoring and fundus examination for hard exudates in patients with elevated UAER to prevent irreversible visual loss.