Anemia associated with new-onset diabetes: Improvement with blood glucose control

Objective: To evaluate the mild normochromic normocytic anemia associated with new-onset diabetes in young, otherwise healthy patients. Methods: We undertook a retrospective review of medical records of patients with new-onset diabetes and unexplained anemia. Anemia was defined as a hemoglobin concentration of less than 12.5 g/dL in women and less than 14 g/dL in men. Patients with obvious causes of anemia, such as renal insufficiency, infection, pancreatitis, deficiency of glucose-6-phosphate dehydrogenase, hemolysis, or acute or chronic blood loss, were excluded from the study. Results: In 16 otherwise seemingly healthy patients with new-onset diabetes, a normochromic normocytic anemia (mean corpuscular volume, 86.4 ± 4 fL) was diagnosed at initial assessment. These 16 patients (8 men and 8 women) had a mean age of 33 ± 10 years. At diagnosis, the mean glycated hemoglobin (HbA1c) was 15.5 ± 3.4%, the mean hemoglobin concentration was 12.5 ± 0.6 g/dL, and the mean hematocrit was 36.2 ± 2%. All patients were treated with insulin. After a mean follow-up of 10.8 ± 17 months, insulin treatment resulted in a decline in HbA1c to 7.7 ± 1.7% (P<0.001; confidence interval [CI], 5.7 to 9.8). The hemoglobin concentration increased to 14.3 ± 0.9 g/dL (P<0.001; CI, 1.22 to 2.38), and the hematocrit increased to 42.1 ± 1.9% (P<0.001; CI, 3.59 to 7.04). All patients had hemoglobin AA and normal levels of hemoglobin A₂. Men and women had equal improvement in hematologic variables after improvement in glycemic control. Conclusion: Some patients with new-onset diabetes have a mild normochromic normocytic anemia that is not attributable to usual causes, such as infection, pancreatitis, or blood loss. Improvement in glycemic control tends to be associated with normalization of hemoglobin levels. The cause of such cases of anemia may be either direct "glucose toxicity" to erythrocyte precursors in the bone marrow or perhaps oxidative stress to mature erythrocytes.