INS and type 2 diabetes mellitus: Insulin therapy, not obligatory in type 2 diabetes but often used in patients with prolonged diabetes duration and poor glycemic control, increased the prevalence of retinopathy to a significant extent (OR = 3.34, 95% CI 1.38–8.09), even after adjustment for age and sex (AOR = 3.28, 95% CI 1.34–8.02).