Use of complementary markers in assessing glycaemic control in people with diabetic kidney disease undergoing iron or erythropoietin treatment

Abstract

AIMS: HbA(1c) values are unreliable in patients with diabetes who have chronic kidney disease who receive iron and/or erythropoiesis stimulating agents. The study aimed to evaluate the utility of the complementary glycaemic markers glycated albumin, fructosamine and 1,5 anhydroglucitol in this group of patients. METHODS: A prospective study of patients with Type 2 diabetes and chronic kidney disease stage IIIB/IV undergoing intravenous iron or erythropoiesis-stimulating agent therapy. Glycaemic control was monitored using HbA(1c), seven-point daily glucose thrice weekly, continuous glucose monitoring, glycated albumin, fructosamine and 1,5 anhydroglucitol. RESULTS: Fifteen patients [9 men; median age 72 years (interquartile range 68-74), follow-up period (16.4 ± 3.7 weeks)] received parenteral iron; 15 patients [11 men; 70 years (interquartile range 62-75), (17.3 ± 3.3 weeks)] received erythropoiesis-stimulating agent. HbA(1c) fell following treatment with both iron [57 mmol/mol (7.4%) to 53 mmol/mol (7.0%), P < 0.001] and erythropoiesis-stimulating agent [56 mmol/mol (7.3%) to 49 mmol/mol (6.6%), P = 0.01] despite mean blood glucose remaining unchanged (iron: 9.55 to 9.71 mmol/l, P = 0.07; erythropoiesis-stimulating agent: 8.72 to 8.78 mmol/l, P = 0.89). Unlike HbA1c , the glycated albumin, fructosamine and 1,5 anhydroglucitol levels did not change following iron [glycated albumin (16.8 to 16.3%, P = 0.10); fructosamine (259.5 to 256 μmol/l, P = 0.89); 1,5 anhydroglucitol (54.2 to 50.9 μmol/l, P = 0.89)] or erythropoiesis-stimulating agent [glycated albumin (17.9 to 17.5%, P = 0.29), fructosamine (324.3 to 306.0 μmol/l, P = 0.52), 1,5 anhydroglucitol (58.2 to 46.7 μmol/l, P = 0.35)]. Despite this, HbA(1c) was consistently the marker most closely related to mean blood glucose before and after each treatment (R range 0.7-0.88). CONCLUSIONS: These data indicate that HbA(1c) was statistically most closely related to mean blood glucose, but clinical trends in glycaemia in patients undergoing iron or erythropoiesis-stimulating agent therapy are likely best assessed by including one of these additional glycaemic markers.