Diabetes and diabetic retinopathy in patients undergoing cataract surgery: a prevalence study-DiCat study report #2

To report on the prevalence of diabetes, diabetic macula oedema (DME) and retinopathy and their respective grading in a large cohort of patients undergoing cataract surgery.

Data on previous diagnosis of diabetes, fasting glucose, glycated haemoglobin, presence and type of retinopathy and other maculopathy of 3657 patients over 55 years of age undergoing cataract surgery in 13 centres scattered throughout Italy were analysed.

A total of 20.4% of patients were known diabetics and 27.9% of diabetics showed signs of retinopathy. Haemoglobin A1C was higher than 48 mmol/L (6.5%) in 32% of diabetics and 2.4% non-diabetics. Fasting blood glucose level was higher than 120 mg/dL in 4.3% non-diabetics and 50% diabetics. Duration of diabetes did not significantly correlate with either fasting glucose or glycated haemoglobin, while higher grades of diabetic retinopathy were significantly more prevalent as duration of disease increased. DME was present in almost 40% of diabetics and 22% of patients showed non-diabetic maculopathy.

Diabetic retinopathy and DME worsen after cataract extraction thus complicating long-term prognosis and requiring expensive injective therapy. Since unknown diabetics represent 2-4% of the many million cataract candidates and even known diabetics show poor metabolic control and high rates of DME, preoperative medical testing and accurate retinopathy screening may prove both ethically necessary and cost-effective.