Age and metabolic control influence lens opacity in type I, insulin-dependent diabetic patients

Cataract is a frequent ocular complication in diabetic patients, but few data are available concerning early modifications occurring in the lens of these patients and their relationship with metabolic control and other clinical parameters. We measured lens opacity in 73 type I, insulin-dependent diabetic patients aging 50 years or less and without clinical evidence of cataract, and in 46 healthy volunteers of similar age. We used a quick, simple, and reliable instrument, the Lensmeter 701, which is based on a back-light scattering quantification system and is able to quantify lens transparency along the nuclear axis. Mean lens opacity was significantly (p = 0.0001) higher in diabetic patients than in the control group, and multiple regression analysis showed that it correlated with age (p = 0.0001) and HbA1c levels (p = 0.009). Moreover in the younger group of patients (age < or =20 years) the only observed correlation was that with Hba1c (p = 0.03), whereas in the older ones (age 21-30 and >30 years) lens opacity correlated with age (p = 0.02 and p = 0.01). These data indicate that early opacifications of the lens occur in type I, insulin-dependent diabetic patients and are influenced by the degree of the metabolic control in the younger ones, whereas the well-known role of aging on lens transparency became prevalent in the older patients. Only longitudinal studies, however, can demonstrate whether these alterations represent any early stage of cataractagenesis and the role of good metabolic control in preventing this ocular complication.