Prediabetes and cataract risk in adults: A systematic review and meta-analysis

Prediabetes, characterized by impaired fasting glucose (IFG), impaired glucose tolerance (IGT), or mildly elevated glycated hemoglobin (HbA1c), represents an intermediate metabolic state potentially contributing to cataract formation. However, the existing evidence for this association remains inconsistent. This meta-analysis aims to elucidate the relationship between prediabetes and cataract in adults. A systematic search was conducted across PubMed, Embase, Web of Science, CNKI, and Wanfang for observational studies assessing the association between prediabetes and cataracts in adults. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using random-effects models to account for heterogeneity. Subgroup analyses were performed based on study design, geographic region, diagnostic criteria for prediabetes, and covariate adjustment. Eight observational studies involving 22,342 participants were included in the analysis. Of these, 5,305 participants (23.7%) had prediabetes, and 7,625 participants (34.1%) had cataracts. Pooled results indicated that prediabetes was associated with a 34% increased odds of cataract compared to individuals with normoglycemia (OR = 1.34, 95% CI 1.11-1.61; p = 0.002; I² = 50%). Sensitivity analyses restricted to high-quality studies (NOS ≥ 7) produced consistent results (OR = 1.29, 95% CI 1.09-1.53; I² = 43%). The association remained significant across subgroups defined by geographic region, mean age, sex, diagnostic criteria for prediabetes, analytical models, and adjustment for sun exposure (all p > 0.05 for subgroup differences). In conclusion, this meta-analysis demonstrates a significant association between prediabetes and cataracts in adults. Given that most included studies were cross-sectional, these findings suggest a potential link rather than a causal relationship, highlighting the need for prospective research to clarify temporal relationships and underlying mechanisms.