Effect of glycemic control on microvascular complications in patients with type I diabetes mellitus

The relation between the control of blood glucose levels and the progression of early diabetic retinopathy and the width of skeletal muscle capillary basement membrane was studied in 54 insulin-dependent diabetic patients. After initial ophthalmologic evaluation including seven-field fundus photography and fluorescein angiography and measurement of levels of glycosylated hemoglobin and width of skeletal muscle capillary basement membrane, the patients were divided into two groups: an experimental group of 30 patients who were treated with continuous subcutaneous insulin infusion and a control group of 24 patients who continued to receive conventional treatment-usually two injections of insulin daily. After a mean follow-up period of 31.4 months, the experimental group had a significant decrease in glycosylated hemoglobin levels as compared with baseline values (mean ± SEM, 7.2 ± 0.3 percent versus 10.1 ± 0.4 percent), reflecting improved control of blood glucose levels. The conventional treatment group had no change in glycosylated hemoglobin levels after a mean of 33.5 months of follow-up. With use of either a modified Early Treatment Diabetic Retinopathy Study grading system or macular microaneurysm counts, the experimental treatment group showed significantly less progression of retinopathy (p <0.05). The skeletal muscle capillary basement membrane width was significantly reduced only in the experimental treatment group with stable or improved retinopathy and was unchanged in the control group. There was a tendency for skeletal muscle capillary basement membrane width to increase in thickness over time in those patients whose retinopathy worsened irrespective of treatment. It is concluded that meticulous diabetic control may slow the progression of early diabetic retinopathy. Changes in skeletal muscle capillary basement membrane width may reflect the course of diabetic retinopathy.