Influence of metabolic control on hemoglobin level in type 1 diabetic patients with nephropathy

Background and Purpose: Diabetic patients with nephropathy show a decline of hemoglobin even at a moderate degree of kidney dysfunction which may impair cardiovascular prognosis. As main reason a disturbed synthesis of erythropoietin (EPO) has been suggested, the pathogenesis, however, is unclear. The clinical significance of metabolic control for the hemoglobin and EPO levels was investigated. Patients and Methods: The following parameters were determined in 185 type 1 diabetic patients: hemoglobin, HbA(1c), calculated creatinine clearance, urinary albumin/creatinine ratio, lipids, high-sensitive C-reactive protein (hsCRP). Serum concentration of EPO was determined in 56 consecutive patients with renal dysfunction. Results: Hemoglobin concentration decreased with declining renal function. Patients were stratified according to median HbA(1c) level (7.4%) in those with better (HbA(1c) < 7.4%) and worse metabolic control (HbA(1c) > 7.4%). In patients with kidney dysfunction, the group with better metabolic control showed higher hemoglobin concentrations than the group with worse metabolic control: 13.6 versus 12.6 g/dl at creatinine clearance < 60 ml/min (p = 0.02). Linear regression analysis revealed metabolic control aside from kidney function, gender, hsCRP and use of ACE inhibitiors as a significant influencing factor of hemoglobin concentration. In patients with renal dysfunction, EPO levels were higher in the group with better than worse metabolic control (13.0 vs. 9.8 U/l). Conclusion: The decline of hemoglobin in diabetic patients with renal dysfunction is mitigated in case of good metabolic control, possibly due to higher EPO concentrations. The results emphasize the clinical significance of a good metabolic control in diabetic patients with nephropathy.