RELATIONSHIP BETWEEN PRORENIN, IGF-I, IGF-BINDING PROTEINS AND RETINOPATHY IN DIABETIC-PATIENTS

Plasma prorenin and renin, serum insulin-like growth factor I (IGF-I) and IGF-binding protein (IGFBP-2 and IGFBP-3) concentrations were meas ured in 22 randomly selected male and female patients with insulin dep endent diabetes mellitus (IDDM) or non-IDDM (NIDDM). Plasma prorenin c oncentration was significantly elevated in patients with proliferative retinopathy (1869.5+/-785.0 mUL(-1), mean+/-SEM) compared to patients with nonproliferative retinopathy (325.5+/-73.2 mUL(-1), P<0.003) and those without retinopathy (318.6+/-47.3 mUL(-1), P<0.007). Similarly, serum insulin like growth factor-I (IGF-I) concentration in patients with proliferative retinopathy (216.3+/-21.5 mu gL(-1)) was significan tly higher than in patients with nonproliferative retinopathy (126.3+/ -14.85 mu gL(-1), P<0.004) and without retinopathy (135.2+/-37.26, P<0 .05). There was moderately strong positive correlation between plasma prorenin and serum IGF-I concentrations (r=0.56, P<0.01). Plasma prore nin concentration was uninfluenced by change in renal function (creati nine clearance, serum creatinine or BUN), but IGF-I levels were invers ely related to creatinine clearance (r=0.67, P<0.002). There was no de monstrable relationship between IGF-binding proteins and prorenin or r enin concentrations, In view of some overlap between plasma prorenin a nd serum IGF-I concentrations in diabetic patients with proliferative and nonproliferative retinopathy, measurement of both markers may be m ore useful in predicting the development of proliferative retinopathy in patients with diabetes mellitus than either measurement alone.