Age-related cataract and its types in patients with and without type 2 diabetes mellitus: A hospital-based comparative study

Objective: To determine the frequency and types of age-related cataract in type 2 diabetic patients compared to non-diabetics. Methods: This comparative, cross-sectional study was carried out at Al-Ibrahim Eye Hospital, Karachi, from July 2014 to June 2015, and comprised both diabetics and non-diabetics. All patients were selected from the out-patient department and had their full ocular examination done, including retinal screening of diabetic patients with non-mydriatic fundus camera. The criterion for diagnosis of cataract was sufficiently advanced lens opacity that caused impaired vision/un-gradable images. Cataract was classified on a morphological basis into cortical, nuclear, posterior sub-capsular and mixed types. Results: Of the 49,384 patients, 4,556(9.2%) were diabetics and 44,828(90.8%) were non-diabetics. Among the diabetics, cataract was found in 1,956(42.9%) compared to 7,050(15.7%) in non-diabetics. Adjusted odds ratio (95% confidence interval) between the two groups was 4.40 (range: 4.11-4.71) (p<0.001). Male-to-female adjusted odds ratio (95% confidence interval) was 2.05 (range: 1.95-2.15) (p<0.001). Nuclear sclerosis was the commonest type in 2,123(46.6%) cataract cases in diabetics whereas posterior sub-capsular cataract was the commonest type in 14,480(32.3%) cases among the non-diabetics. Conclusion: Cataract was four times more common in diabetics and twice more frequent in men. Nuclear sclerosis was the commonest type of cataract in diabetic patients.