Metabolic cataracts in newly diagnosed diabetes.

The morphologically distinct diabetic or 'metabolic' cataract is rare in newly diagnosed insulin dependent diabetes. The cases described are of five adolescents (three girls, two boys) with newly diagnosed insulin dependent diabetes who developed metabolic cataracts close to the time of diagnosis (0-16 months). They all had a prolonged duration of symptoms before diagnosis (4-24 months) and high glycated haemoglobin levels at diagnosis (15-21%). The pathogenesis of diabetic cataract is not well understood in humans. An attempt is made to link clinical observations with evidence from experimental animal models to understand the mechanism of cataract formation, with particular reference to the aldose reductase pathway. It is recommended that the lens and retina are examined at the onset of diabetes in all children, especially those who have a prolonged duration of symptoms before diagnosis and who report persistent blurred vision.