2015 Volume 58 Issue 2 Pages 121-127
The HbA1c level is widely used as an indicator of glycemic control. However, this parameter does not accurately reflect the degree of glycemic control in patients with variant hemoglobin or various types of anemia. We experienced two cases of variant hemoglobin in which the patients received the administration of oral hypoglycemic agent (s) due to spuriously high levels of HbA1c. The HbA1c levels measured using immunoassays were high in both cases, although the patients did not exhibit hyperglycemia. The administration of a sulfonylurea induced hypoglycemia in one case but not the other case, in which the patient received treatment with a DPP-4 inhibitor and biguanides. After stopping the doses of the oral hypoglycemic agent (s), one patient showed borderline glucose tolerance, while the other demonstrated normal glucose tolerance, as evaluated according to oral glucose tolerance tests. We found the same heterozygous mutation on an analysis of the globin gene in each case and diagnosed the patients with hemoglobin Himeji [β140Ala→Asp]. From these experiences, the diagnosis of diabetes mellitus should not be made based only on the HbA1c level.
