Senile lens changes and diabetes in two population studies.

Clinical and epidemiologic studies of the association between senile cataract and diabetes have produced what initially appears to be conflicting evidence. Three studies of extracted cataract have found a positive association in persons less than 70 years old. Conversely, two studies of senile lens changes (including aphakia) reported no association with diabetes. These apparently disparate findings led to the hypothesis that the diseases are in fact not associated, but that diabetics are more likely to be referred to ophthalmologists and therefore to have cataracts removed. We tested this hypothesis with data from two population surveys, the Framingham Eye Study and the Health and Nutrition Examination Survey (HANES). Both studies showed a marked excess prevalence of senile cataract (including aphakia) in diabetics less than 65 years old (relative risks of 4.02 and 2.97, respectively). Beyond the age of 64 years, the HANES study but not the Framingham study showed an excess prevalence, although it was less marked (relative risks of 1.63 and 1.02, respectively). For senile lens changes other than cataract, both studies showed little, if any, association with diabetes. Our results for cataract (whether removed or not) were generally consistent with those of previous studies of extracted cataract for persons under the age of 70 years and for persons aged 70 years or more. The two studies that reported no association between lens changes and diabetes provided information inadequate to support or refute the foregoing findings. The various studies failed to support increased referral of diabetics to ophthalmologists as an explanation for the observed association. All these studies found the association in persons less than 70 years old, whether the cataract had been removed or not.