Increased response to subcutaneous erythropoietin on type I diabetic patients on CAPD: is there a synergistic effect with insulin?

OBJECTIVE: To evaluate the effect of subcutaneous erythropoietin (SC EPO) on the treatment of anemia in diabetic and nondiabetic continuous ambulatory peritoneal dialysis (CAPD) patients. DESIGN: A resistance index was designed for measuring the relative EPO response, dividing EPO dose (U/kg/week) by the hemoglobin (Hb) increment with respect to the basal level. PATIENTS: Eleven nonselected type I diabetic patients using subcutaneous insulin compared with 16 nondiabetic controls, all on CAPD therapy. RESULTS: The two groups showed similar mean baseline hemoglobin levels (7.4 D-I and 7.7 non-D, g/dL). There was a statistically significant lower resistance index for diabetics (13.8 +/- 9.7 U/kg/g Hb increment) compared to nondiabetic (55.8 +/- 128, p < 0.001). Multivariate analysis confirmed an independent association between diabetes and resistance index. The response to EPO was slightly better among those diabetic patients with lower levels of serum parathyroid hormone (iPTH) (PTH-resistance index, correlation coefficient, r = 0.7, p < 0.05). No other differences, apart from the use of subcutaneous insulin, were found between diabetics and controls. Although diabetic patients had an increased response to EPO, they had no more frequent side effects than nondiabetics. CONCLUSIONS: According to our results, we suggest that factors related to insulin-dependent diabetes seem to be involved in a favorable response to SC EPO. Hyperinsulinemia derived from subcutaneous use of insulin might act as a comitogen with the induced increments of serum erythropoietin.