Dietary glycemic index, glycemic load and risk of age-related cataract extraction: a case-control study in Italy.

PURPOSE: Although a role of glycemic index (GI) and glycemic load (GL) in age-related cataract development is plausible, a few studies, all conducted in USA or Australia, provided results on this issue. The aim of the present study was to provide new original data from a Mediterranean population. METHODS: We analyzed data from an Italian case-control study including 761 cases with cataract extraction and 1,522 hospital controls, frequency-matched with cases by center, sex, and age. Multivariate odds ratios (ORs) for GI and GL intakes were obtained from logistic regression models after allowance for major confounding factors, including non carbohydrate energy intake, smoking, and diabetes. RESULTS: The ORs of cataract extraction for the highest versus the lowest tertile were 1.20 (95% confidence interval, CI 0.91-1.57) for GI and 1.57 (95% CI 1.16-2.13) for GL, with a statistically significant trend in risk for GL (p < 0.01). Results were materially unchanged when diabetics were excluded from the analysis. No heterogeneity emerged across strata of sex, age, education, smoking habits and body mass index. CONCLUSIONS: The present study supports a positive association between dietary GL and the risk of cataract extraction, independently from diabetes, and a lack of association for GI.