Secondary prevention of diabetic retinopathy in type I diabetes mellitus. Dependence on retinopathy status before the intervention

Abstract

To assess prospectively the effect of improving the metabolic state on the course of diabetic retinopathy in relation to the extent of retinal changes before intervention. 140 patients with type I (insulin-dependent) diabetes mellitus (IDDM) (55 men, 85 women; mean age 30 +/- 11 years; mean duration of illness 11 +/- 8 years), underwent intensified insulin treatment and were then followed for 4 years. At the beginning of the trial fundoscopy was unremarkable in 68 patients (stage 0), a few microaneurysms and (or) punctate bleeding (stage 1) in 21, nonproliferative retinopathy (stage 2) in 27, preproliferative retinopathy (stage 3) in six, proliferative retinopathy (stage 4) in 14, and proliferative retinopathy with complications (stage 5) in four. The average retinopathy stage was 1.2 +/- 1.0, mean HbA1c value 7.0 +/- 1.3%). The retinopathy remained unchanged in 94 patients (group A), it improved in 16 (group B), and deteriorated in 30 (group C). There was no significant change in mean HbA1c value in any of the groups (A: 6.2 +/- 0.9%; B: 6.4 +/- 1.0%; C: 6.3 +/- 6.0%). There were also no differences with respect to blood glucose, M-value according to Schlichtkrull, frequency of hypoglycaemia, serum lipids, blood pressure and renal biopsy parameters. However, significant differences (P < 0.001 C vs. A and B) were found in relation to duration of diabetes (A: 9.3 +/- 7.2 years; B: 8.8 +/- 8.6 years; C: 16.9 +/- 7.8 years) and mean retinopathy stage at beginning of the study (A: 0.8 +/- 0.8; B: 1.2 +/- 0.7; C: 2.4 +/- 1.6). Decisive for the course of retinopathy in patients with IDDM of long duration and secondarily optimised metabolic state is the duration of illness and especially the degree of fundal changes when intensified insulin treatment is undertaken.