Association of Glycated Haemoglobin and Serum Apolipoproteins with Diabetic Retinopathy: An Indian Overview.

INTRODUCTION:India is presently facing an epidemic of diabetes mellitus and the risks of chronic complications from the disease are associated with the duration of the disease as well as the degree of hyperglycaemia. Diabetic retinopathy is a known microvascular complication of diabetes mellitus and is the most common cause of blindness in the western countries.Apolipoproteins are the protein component of lipoproteins. Apart from acting as structural proteins, they also act as cofactors to various enzymes. AIM:To measure the levels of serum apolipoproteins and glycated haemoglobin in cases of diabetic retinopathy and to assess their association with the stages of diabetic retinopathy. MATERIAL AND METHODS:The 135 diabetic cases [with (110) and without (125) retinopathy] attending the Ophthalmology OPD of this tertiary care hospital were included in the present study. Following retinoscopy, the patients were classified as Non-Proliferative Diabetic Retinopathy (NPDR) (n=75) and Proliferative Diabetic Retinopathy (PDR) (n=35). The controls (n=100) were age and sex matched patients who did not have diabetes. The cases and controls were assessed for HbA1c, total cholesterol, triglycerides, HDL cholesterol, Apo A-I and Apo B-100. RESULTS:The HbA1c was found to be higher in diabetics without retinopathy (7.02%) as compared to controls (5.58%) (p<0.05) and the highest value was seen in the mild NPDR group (8.82%). The mean value of Apo A-I was found to be lowest in the diabetics without retinopathy at 88 mg/dl and the highest in severe NPDR at 167 mg/dL. The mean value of Apo B-100 was found to be highest in severe NPDR at 114 mg/dL. The mean value of HDL cholesterol was lowest in moderate NPDR at 36.6 mg/dl. Total cholesterol was highest in severe NPDR at 280.88mg/dl while triglyceride was highest in severe NPDR at 286.4mg/dl. CONCLUSION:In our study, the level of HbA1c was found to range from 5.58% in non-diabetic to 8.82% in mild NPDR. There was a clear association between Apo B-100 and total cholesterol, triglycerides with the highest value of each parameter seen in the severe NPDR group. There was a discordance noted in the levels of HDL and Apo A-I in various groups. Apo B-100 values may be of value in prognosis of diabetic retinopathy as higher values may result in progression of the disease. Further studies involving Lp(a) and homocysteine may be required in cases of diabetic retinopathy.