A systematic review of risk factors for cataract in type 2 diabetes.

Type 2 diabetes (T2D) is a risk factor for cataract development. With T2D prevalence increasing, the burden of cataract-associated vision loss will also increase. We aimed to characterise cataract diabetes-specific risk factors to assist prevention and management strategies. As part of a systematic review, two investigators independently searched online electronic databases according to a predetermined protocol for relevant published data to end-March 2018. Studies were included if they were longitudinal with ≥100 participants, diabetes was defined, a description of cataract assessment was provided, data were from humans, and the reports were in English. Study quality was assessed using the Newcastle Ottawa Scale and GRADE. Of 5255 publications identified, 19 from 13 study populations were included. The overall risk of bias was low. There was between-study variability. Age and glycaemic control were consistently associated with cataract development in T2D, but blood pressure, diabetes duration, sex, and aspirin use were not. Serum lipids and smoking remain possible risk factors, but available data are inconclusive. Glycaemia is the only consistent modifiable risk factor amongst a range of candidate variables. Due to the lack of consistency of the available evidence, and since mortality associated with T2D is declining with the likelihood of increased cataract-associated vision loss, additional well-conducted longitudinal studies are needed to identify modifiable risk factors that could prevent or delay cataract formation.