Assessment of markers of glycaemic control in diabetic patients with chronic kidney disease using continuous glucose monitoring

Aim: Due to altered red blood cell survival and erythropoietin therapy glycated haemoglobin (HbA1c) may not accurately reflect long-term glycaemic control in patients with diabetes and chronic kidney disease (CKD). Glycated albumin (GA) and fructosamine are alternative markers of glycaemia. The aim of this study was to investigate the accuracy of HbA1c, GA and fructosamine as indicators of glycaemic control using continuous glucose monitoring. Methods: HbA1c, GA and fructosamine concentrations were measured in 25 subjects with diabetic nephropathy (CKD stages 4 and 5 (estimated glomerular filtration rate < 30 mL/min per 1.73 m2)) matched with 25 subjects with diabetes and no evidence of nephropathy. Simultaneous real-time glucose concentrations were monitored by continuous glucose monitoring over 48 h. Results: GA correlated significantly to mean glucose concentrations in patients with and without CKD (r = 0.54 vs 0.49, P < 0.05). A similar relationship was observed with fructosamine relative to glucose. A poor correlation between HbA1c and glucose was observed with CKD (r = 0.38, P = ns) but was significant in the non-CKD group (r = 0.66, P < 0.001). The GA/HbA1c ratio was significantly higher in diabetic patients with CKD compared with controls (2.5 +/- 0.4 vs 2.2 +/- 0.4, P < 0.05). HbA1c values were significantly lower in CKD patients, relative to non-CKD patients at comparable mean glucose concentrations. Conclusion: HbA1c significantly underestimates glycaemic control in patients with diabetes and CKD stages 4 and 5. In severe CKD, GA more accurately reflects glycaemic control compared with fructosamine and HbA1c and should be the preferred marker of glycaemic control.