Determination of Reference Intervals of HbA1C (DCCT/NGSP) and HbA1C (IFCC) in Adults
Navapun Charuruks, MD*, Anna Milintagas, BSc**, Phandee Watanaboonyoungcharoen, MD*, Chomsri Ariyaboonsiri, MD*
Affiliation : * Department of Laboratory Medicine, Faculty of Medicine, Chulalongkorn University ** Department of Laboratory Medicine, King Chulalongkorn Memorial Hospital, Thai Red Cross
Objective : To establish HbA1C reference intervals according to DCCT/NGSP (HbA1C DCCT/NGSP) and IFCC
(HbA1C IFCC) in adults.
Study
Design : The study was a descriptive study.
Materials and Methods : The study was done in 144 subjects, with 99 males and 45 females, aged between 19
to 78 years old. All subjects had normal vital signs, physical examination, chest X-ray. Subjects who had
hyperglycemia, renal problem, liver problem, anemia, and/or hemoglobinopathy were excluded from the
present study.
Results : Reference intervals of HbA1C (DCCT/NGSP) is 5.47% (4.79-6.15) and HbA1C (IFCC) is 3.66%
(2.88-4.44). The authors also found very high correlation between HbA1C (DCCT/NGSP) and HbA1C (IFCC)
of total, male, female, < 35 years old, and > 35 years old, r = 0.9995, 09997, 0.9992, 0.9988, and 0.9999,
respectively.
Conclusion : The authors found that HbA1C (DCCT/NGSP) and HbA1C (IFCC) are not affected by sex but are
influenced significantly by age group. Since HbA1C (IFCC) will be widely used in routine diabetes manage-
ment, the authors recommend all laboratories provide the results of HbA1C in both DCCT/NGSP and IFCC
methods during this interim period.
Keywords : HbA1C (DCCT/NGSP), HbA1C (IFCC), Reference intervals
