Diabetes,fasting blood glucose and age-related cataract: the Blue Mountains Eye Study

AIMS. To examine the relationship between diabetes and the presence of cortical, nuclear and posterior subcapsular (PSC) cataract in a defined older population, while controlling for known cataract risk factors. METHODS. Slit-lamp and retroillumination lens photographs were taken on 3654 participants attending the population-based Blue Mountains Eye Study during 1992-94. Masked grading of the photographs was performed using the Wisconsin Cataract Grading System. RESULTS. 217 subjects (5.9% of the population) had previously diagnosed diabetes and 66 (1.8%) had diabetes diagnosed from fasting blood glucose measurements. Cortical cataract, PSC and past cataract surgery were associated with known diabetes in age-sex adjusted models. However, only PSC (odds ratio (OR) 1.8, 95% confidence interval (CI) 1.0-3.1) and past cataract surgery (OR 2.5, CI 1.5-4.2) remained statistically significantly associated with diabetes after further adjustment for other known cataract risk factors. Increasing therapy, as an index of diabetes severity (oral or insulin treatment, compared to treatment by diet alone), was associated with a markedly increased risk of PSC (OR 5.4). CONCLUSIONS. These findings support previous research showing that diabetes has a harmful effect on the lens. The markedly increased risk for PSC may also have been reflected in the association found between diabetes and past cataract surgery. Contrary to findings from the Beaver Dam Eye Study, we found only a weak association with cortical cataract, which was not statistically significant after adjusting for other known cataract risk factors.