Association of Erythrocyte Aldose Reductase Activity with Diabetic Complications in Type 1 Diabetes Mellitus

Erythrocyte aldose reductase was isolated and its activity measured in 72 Type 1 (insulin dependent) diabetic patients and 21 age and sex matched non‐diabetic subjects. The diabetic patients were categorized into two groups in terms of presence (n = 29) or absence (n = 43) of severe diabetic complications. Age, sex, duration of diabetes and HbA_1c levels were matched between the diabetic groups. Erythrocyte aldose reductase (mean ± SEM) was increased in patients with Type 1 diabetes compared to the non‐diabetic subjects (7.22 ± 0.24 vs 5.66 ± 0.19 Ul‐erythrocytes^‐1, < 0.0001). There was a four‐fold variation in its activity among the diabetic patients (3.38‐12.23 Ul‐erythrocytes^‐1). The enzyme activity was significantly higher in patients with complications than those without (8.17 ± 0.39 vs 6.58 ± 0.26 Ul‐erythrocytes^‐1, p < 0.002). When the patients were stratified by duration of the disease, the enzyme activity was highest in patients who had developed complications with a duration of less than 20 years and lowest in those without complications for 20 years or longer (8.54 ± 0.48 vs 6.46 ±p± 0.33 Ul‐erythrocytes^‐1, p < 0.002). Patients who had an aldose reductase activity greater than the mean + 2SD of that seen in non‐diabetic controls were four times more likely to have diabetic complications than those whose enzyme activity fell within 2SD of non‐diabetic individuals (p < 0.0005). We conclude that the activity of aldose reductase varies among Type 1 diabetic patients and the differences in its activity may result in a variable susceptibility of these patients to the complications of the disease. 1993 Diabetes UK