The glycemic levels of anesthetized ZDF rats were, however, unaffected as were those of insulin treated ZDFs which remained at 5–12 mmol/L.ERG measurements were made under dark-adapted (scotopic) and light-adapted (photopic) conditions periodically between 8 (approximately 2 weeks after the onset of hyperglycemia in ZDF rats) and 22 weeks of age, after which untreated diabetic animals start to develop visible cataracts. This evidence concerns the gene INS and Hyperglycemia.