Two-year experience with continuous subcutaneous insulin infusion in relation to retinopathy and neuropathy

Thirty patients with insulin-dependent diabetes mellitus (IDDM) who had advanced background retinopathy were randomized to unchanged conventional treatment (UCT) or to continuous subcutaneous insulin infusion (CSII). They were followed prospectively for 2 yr. The mean blood glucose and hemoglobin A1C (HbA1C) were significantly lower in the CSII group than in the UCT group. The mean blood glucose and HbA1C did not change from the first to the second year in either of the treatment groups in spite of less frequent home-monitoring of blood glucose and less frequent outpatient visits during the second year. Four patients in the CSII group and five in the UCT group developed proliferative retinopathy. However, a marginally significant trend was found toward more frequent improvement of retinal morphology in the CSII group (47%) than in the UCT group (13%). Beat-to-beat variation was found to deteriorate significantly with UCT compared with a nonsignificant improvement with CSII therapy. Vibration sense was unchanged in both treatment groups. It is concluded that near-normal blood glucose levels can be maintained with CSII therapy in spite of less frequent home-monitoring of blood glucose and outpatient visits. Furthermore, established background retinopathy may progress to proliferative retinopathy in spite of 2 yr of near-normal blood glucose levels. However, a marginally significant trend toward more frequent improvement of retinal morphology was found among CSII-treated patients compared with conventionally treated patients. Large-scale, prospective, randomized studies are needed to confirm these results.