The effect of continuous insulin infusion as compared with conventional insulin therapy in the evolution of diabetic retinal ischaemia. Two years report

Continuous subcutaneous insulin administration (CSII) is known to provide a better glucose control than conventional insulin treatment (CIT). Early anecdotal reports claimed that diabetic retinopathy could be dramatically reversed by CSII treatment. More prolonged studies were however less enthusiastic: only slightly better retinal outcome was observed in those diabetic patients in CSII regimen. The aim of the present study was to investigate the mid-term effects of CSII, as compared with conventional treatment, on the evolution of the ischaemic retinal changes in a group of diabetic subjects. A multicentre prospective study was designed by the Italian CNR and carried out by the Universities of Padua, Milan, Perugia and the Fidia Research Laboratories. Thirty-eight Type I insulin-dependent diabetic patients were blindly assigned by paired randomization to CSII or CIT after matching for sex, age, duration of diabetes and retinal status. To assess the evolution of retinopathy, fluoroangiographic changes of ischaemic areas were blindly evaluated and reported as improved, stable and worsened. The degree of ischaemia was also scored by means of a quantitative method (Dokumator). At the baseline metabolic parameters were not statistically different between the two treatment groups. After 24 mo, CSII patients reached a better glycaemic control than those treated by CIT (daily glucose profile, glycosylated haemoglobin were significantly lower in the CSII group). While qualitative evaluation of retinal changes showed a slightly but not significantly better outcome in the CSII patients, quantitative assessment demonstrated a significantly lower deterioration in the CSII group. Furthermore, an evident correlation was observed between systolic blood pressure and retinal deterioration. In conclusion, our results support the point of view that, even though CSII does not prevent the development of proliferative retinopathy, the deterioration of retinal microangiopathy, even at a relatively advanced stage such as ischaemic retinopathy, could be retarded by strict metabolic control achieved by CSII.