Effect of Multiple Daily Insulin Injections on the Course of Diabetic Retinopathy

Forty-two diabetic patients on insulin once a day in the early stage of diabetic retinopathy were randomly assigned to one of two kinds of insulin regimen, i.e., single or multiple daily injections. Retinal changes were quantitatively estimated by counting the microaneurysms (MAs) observed on fluorescein angiograms at the posterior pole of the more diseased eye. Baseline characteristics of the two groups were not significantly different. These included duration of diabetes, age at diagnosis, daily dose of insulin, amount of urinary sugar excreted in 24 hours, fasting blood sugar (FBS), and number of MAs. During the follow-up (mean duration of three years) the mean yearly progression in the number of MAs was significantly less in the multiple- than in the single-injection groups: 1.8 +/- 0.7 versus 7.2 +/- 1.9 (p less than 0.01; nonparametric test: p less than 0.02). Final values were, respectively, MAs: 15.2 +/- 4.9; 33.0 +/- 7.9; glycosuria (gm./24 hrs): 20.6 +/- 2.5; 27.5 +/- 4.3; FBS (mg./100 ml.): 154 +/- 15; 195 +/- 11. P values comparing the two groups were less than 0.02, less than 0.02, and less than 0.05. Thus, in this clinical trial, made under routine treatment conditions, the use of divided daily insulin injections was effective in improving diabetic control and delaying retinal changes.