Usefulness of Plasma Glucose Adjusted #C (labile HbA1c fraction) Levels for the Screening of Variant Hemoglobin with Diabetes Mellitus

Labile HbA1c migrates in the #C fraction with modified hemoglobin (Hb) (such as carbamylated Hb, acetaldehyde Hb, and acetylated Hb) when HbA1c is measured by Arkray's high-performance liquid chromatography (HPLC). We previously reported the usefulness of #C levels for the screening of variant Hb without diabetes mellitus. Because the #C levels are affected by plasma glucose levels, we investigated the usefulness of plasma glucose adjusted #C (PGa#C) for the screening of variant Hb complicated with diabetes mellitus. In this study, nine types of variant Hb in nine diabetic patients were included. HbA1c and the #C fraction were measured by Arkray's HPLC. Furthermore, we established a calculation formula for PGa#C by using the regression equation of #C and plasma glucose of 2,299 diabetic patients without variant Hb. If the cutoff value of PGa#C for the screening of variant Hb with diabetes mellitus was set at 1.3% or lower and 2.3% or higher, sensitivity and specificity were 89% and 99.8%, respectively. The PGa#C levels in all four slow moving variant Hb with diabetes were less than 1.3%, while the PGa#C levels of fast moving variant Hb with diabetes were abnormal values in four out of five patients [high #C level in one and low #C levels in three patients]. The screening of variant Hb with diabetes with high sensitivity and high specificity was possible by using the same cutoff values for the reference range of PGa#C as the #C values reported in non-diabetic subjects.