Risk factors for cataract in Chinese patients with type 2 diabetes: evidence for the influence of the aldose reductase gene

There is evidence that the development of retinopathy in type 2 diabetes is associated with a microsatellite polymorphism at 5' of the aldose reductas e gene. The study examined whether cataract was associated with clinical/me tabolic factors and/or the microsatellite polymorphism using a cohort of co nsecutively recruited Hong Kong Chinese patients with type 2 diabetes (n = 567). Amongst these patients, 157 (28%) had cataract. The patients with cat aract were older in age and age at diagnosis and had longer diabetes durati on than those without cataract (all at p < 0.01). They also had higher syst olic blood pressure (P < 0.01), HbA(1c) (p < 0.05) and fasting plasma gluco se levels (p < 0.01; all with adjustment for the significance). Moreover, w e found that the patients with cataract over-presented the microsatellite a llele Z (23 vs. 30%, p < 0.01) and its genotypes (Z,Z + Z,non-Z; 38 vs. 50% , p < 0.01), but under-presented the allele Z - 4 (8.3 vs 4.8%, p < 0.05) a nd its genotypes (Z - 4, Z - 4 + Z - 4,non-Z - 4; 16 vs. 10%, p < 0.05). Us ing multiple logistic regression analysis (R-2 = 0.25, P < 0.01), we found that the presence of cataract was correlated positively with age, but inver sely with the presence of allele Z - 4. In conclusion, our data indicate th at the occurrence of cataract is common in the Chinese type 2 diabetes popu lation, with age and the aldose reductase gene as important determinants.