Objective: To investigate the effects of glycosylated hemoglobin A1c (HbA1c) from the patients with double heterozygotes Hb Q-H and Hb J-Bangkok combined with β-thalassemia on the results of different HbA1c detection systems. Methods: Blood samples from 20 healthy adults and 20 patients with type 2 diabetes mellitus (T2DM) were collected to assess the results of five glycosylated hemoglobin detection systems. Blood samples from one Hb Q-H patient and one Hb J-Bangkok patient with β-thalassemia were also collected, and they were performed hemoglobin capillary electrophoresis with Capillarys2 and globin gene analysis by gap-PCR, PCR-RDB and DNA sequencing. The levels of HbA1c in all samples were detected by BioRad VARIANT Ⅱ (VⅡ), BioRad VARIANT ⅡTurbo2.0 (V Ⅱ-T2.0), Capillarys 2 Flex Piercing (C2FP), Primus Ultra2 (Ultra2) and Roche PPI 800 (PPI 800) glycosy lated hemoglobin detection instruments, respectively. For the samples with double heterozygotes, the levels of HbA1c were detected for 3 times each sample, and the results were preserved and analyzed. Results: The genotype of the Hb Q-H sample was --α QT /--SEA;β N /β N , and HbA1 CD74 G＞C mutation occurred in globin α1 chain, forming Hb Q-Thailand hemoglobin variant without normal α-globin peptide chain. The genotype of Hb J-Bangkok combined with β-thalassemia was αα/αα;βCD56/βCD41-42, and the point mutation of GGC＞GAC occurred at codon 56 of globin β-chain, forming Hb J-Bangkok hemoglobin variant without normal β-globin peptide chain. For the Hb Q-H sample, HbA1c results were reported by 3 of 5 HbA1c detection systems. The chromatograms of VⅡ and VⅡ-T2.0 detection systems were obviously different from normal chromatograms, and HbA1c results were not reported. However, the chromatograms of the C2FP system were similar to normal chromatograms, and the result of HbA1c was 3.7%. The Ultra2 system and PPI system reported the HbA1c results, 5.3% and 5.7%, respectively, without abnormal alarm. For the Hb J-Bangkok with β-thalassemia sample, HbA1c results were also reported by 3 of 5 HbA1c detection systems. The chromatograms of VⅡ and Sebia detection systems were obviously different from normal chromatograms, and HbA1c results were not reported. However, the chromatograms of VⅡ-T2.0 system were different from normal chromatograms, and a P4 peak (84.9%) was found. The HbA1c result was reported as 4.7%. The Ultra2 system and PPI system reported the HbA1c results, 4.7% and 3.8%, respectively, without abnormal alarm. Conclusion The samples from the Hb Q-H patient and the Hb J-Bangkok patient with β-thalassemia do not contain normal HbA, and there should be no HbA1c results. The chromatograms of VⅡ and VⅡ-T systems are obviously abnormal, indicating that the results can not be reported. The C2FP system is interfered obviously by Hb Q-H, but reports the HbA1c results, while it does not report the HbA1c results of Hb J-Bangkok combined with β-thalassemia. Both of Hb Q-H and Hb J-Bangkok have obvious interference to PPI and Ultra2 detection systems.