Background: Anemia (defined by the World Health Organization as a hemoglobin level of less than 13 mg/dl in men and less than 12 mg/dl in women) is common in diabetic patients, particularly in those with reduced renal function. Most studies attribute anemia in diabetic patients to kidney function impairment. There are no controlled systematic studies of the prevalence and predictors of anemia in patients with diabetes in the absence of overt nephropathy.
Objective: This retrospective cohort study was designed to measure the prevalence of anemia in diabetic patients with normal kidney function (estimated glomerular filtration rate (EGFR) greater than 90 ml/min/1.73 m2 and negative micro albuminuria) and compare it to a control group of non-diabetic patients. The study was designed to investigate diabetes as an independent risk for causing anemia.
Methods: We undertook a retrospective review of medical records of 400 patients (older than 18 years old) visiting the outpatient clinic in our institution between January and June 2015. 200 patients with diabetes (glycosylated hemoglobin (HgA1C) greater than 7) were compared to 200 non-diabetic patients (HgA1C level below 5.6), to identify the prevalence of anemia, with and without kidney disease and any other associated factors.
Results:The prevalence of anemia in all diabetic patients was 22% vs. 9% in non-diabetic group (OR: 2.69, 95% CI; 1.49 to 4.86, P = 0.001). Out of the 22% (n = 44) anemic patients, 18 patients had anemia with normal kidney function, out of those; 5 had iron deficiency anemia and one had autoimmune disease, while the remaining 12 patients (6%) did not have any obvious cause of anemia other than diabetes vs. 2 patients (1%) in non-diabetic patients who we did not find any explanation for the their anemia (OR: 6.6, 95% CI; 1.45 to 30, P < 0.015).
Conclusion: Most studies have highlighted an association between anemia and nephropathy in diabetic patients. This retrospective cohort study suggests a high incidence of anemia with unidentified pathology in the diabetic population. The mechanism of this anemia is not well understood, although direct glucose toxicity to erythrocyte precursors in the bone marrow or oxidative stress to mature erythrocytes are both possibilities. Prospective study of hemoglobin levels in patients with diabetes may help elucidate the precise mechanism of anemia in this group.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.