Effect of long term glycemic control on the onset of retinopathy in iddm subjects. A longitudinal and retrospective study.

A random sample of 78 IDDM patients were studied retrospectively with regard to longitudinal glycemic control from onset of diabetes in relation to onset of retinopathy from 10-20 years of the disease. During the latter period 40 patients developed retinopathy (retinopathy group) whereas 38 did not (no retinopathy group). Sex ratio as well as age at onset of diabetes was similar between the two groups. Also glycemic control was similar during the first five years of diabetes as assessed from glucose determinations in urine and blood. However, during the period from 5-10 years of diabetes duration glycemic control of the retinopathy group deteriorated significantly in comparison to previous years and in comparison with the non-retinopathy group. The frequency of control visits did not differ between groups; however patients in the retinopathy group more frequently changed from one institution of treatment to another than did the other patients. This study demonstrates that glycemic control deteriorates with time in a sub-group of IDDM subjects and supports the concept that onset of retinopathy depends on cumulative exposure to hyperglycemia.