Degree of discrepancy between HbA1c and glycemia in variant hemoglobin is smaller when HbA1c is measured by new-type Arkray HPLC compared with old-type HPLC

Objectives: Although variant hemoglobin mainly demonstrates inappropriate HbA1c values measured by high-performance liquid chromatography (HPLC), these values differ depending on the HPLC model. In the 1990s, old-type HPLC models were replaced with new-type HPLC models which could separate stable HbA1c from labile HbA1c and modified hemoglobin. This study compared HbA1c values in subjects with variant hemoglobin measured using old-type Arkray HPLC (HA-8150) and new-type Arkray HPLC (HA-8160 or HA-8180).

Design and methods: This study included non-diabetic subjects with apparently low HbA1c values who had variant hemoglobins due to a β-chain heterozygous mutation. HbA1c was measured by old-type HPLC in 28 subjects with 12 variant hemoglobins (group 1) and new-type HPLC in six subjects with four variant hemoglobins (group 2). When HbA1c was measured by HPLC (HPLC-HbA1c), HbA1c measured by immunoassay (IA-HbA1c) and glycated albumin (GA) were also measured.

Results: IA-HbA1c and GA did not significantly differ between both groups. However, HPLC-HbA1c in group 2 was significantly higher than that in group 1 (group 1: 2.9 ± 0.7% vs. group 2: 3.7 ± 0.2%, P = 0.006).

Conclusions: When HbA1c in subjects with variant hemoglobin is measured by new-type Arkray HPLC, the degree of discrepancy between HbA1c and glycemia is smaller compared with that measured by old-type HPLC.