Reference Range of Hemoglobin A1c in
Ibrahim A Ai1*, Hisham M Abdel Rahim1, Babiker Almobasher1, Rihab M Badi2, Abdarahiem Alborai3, Abdelmohisen Hussein4, Kamal M Awad4, Elmoataz H Taha5, Aamir A Elmagzoub1 and Omer A Musa1
1Department of Physiology, National Ribat University, Sudan
2Department of Physiology, University of Khartoum, Sudan
3Department of Physiology, Omdurman Islamic University, Sudan
4Department of Physiology, Gadarif University, Sudan
5Department of Physiology, Dongola University, Sudan
Submission: February 28, 2018; Published: March 19, 2018
*Corresponding author: Ibrahim Abdelrhim Ali, Department of Physiology, Faculty of Medicine, National Ribat University, Sudan,
How to cite this article: Ibrahim A Ai, Hisham M Abdel Rahim, Babiker Almobasher, Rihab M Badi, Abdarahiem Alborai, Abdelmohisen Hussein. Kamal M
Awad,Reference Range of Hemoglobin A1c in Khartoum State. Anatomy Physiol Biochem Int J: 2018; 4(4): 555644. DOI: 10.19080/APBIJ.2018.04.555644.
Introduction:Hb A1c is now used largely for DM control, the normal values of Hb A1c in Sudanese must be established for the clinical diagnosis and follow up of DM. The normal value used in Sudanese laboratories is up to 6.5% which is Caucasians.
Objective:The study aimed to establishing the normal Sudanese reference range for Hb A1c in Khartoum state.
Methods: A Cross sectional study was conducted between 2016-2018 in Khartoum state capital of Sudan on healthy Sudanese subjects of both sexes with age group 20 -60years. 444 Sudanese adult volunteers were included – 91 males 353 were females. All of them were assessed by a questionnaire covering age, gender, past medical history, family history, physical activity, daily caloric intake, smoking history, and body mass index (BMI) was calculated by standard techniques followed by complete clinical examinations. A sample of five ml venous blood was taken for fasting blood glucose to exclude DM and Hb A1c was measured using modified ELISA reader known as COPAS Integra 800.
Results:The mean of age was 25.4±9.2 %. The mean of Hb A1c was 4.2±1.8% SD and with range of 1.2-6.5%.
Conclusion: This study showed significant variations in the level of Hb A1c of healthy Sudanese in comparison with the reference ranges of international parameters. The study results revealed an urgent need to build national reference ranges for all hematological and other physiological parameters for Sudanese population in the near future
Abbrevations: ADA: American Diabetes Association; MENA: Middle East and North Africa; FBG: Fasting Blood Glucose; FMOH: Federal Ministry of Health in Sudan; NRU: National Ribat University; ELISA: Enzyme Linked Immunosorbent Assay; FBS: Fasting Blood Sugar
Hb A1c, is a glycated hemoglobin formed by the glycosylation of hemoglobin. The term glycated hemoglobin represents the glycaemic status of a person over the last two to three months [1-5]. According to the American Diabetes Association (ADA) Guidelines 2007, the value of Hb A1c should be kept below 7% in all diabetics and according to the same guidelines, Hb A1c is now referred to as A1c . Hemoglobin A1c was first separated from other forms of hemoglobin by Huisman and Meyering in 1958 using a chromatographic column . About 50 years ago Glycated haemoglobin (Hb A1c) was initially identified as an “unusual” haemoglobin in diabetic patients by Samuel Rahbar in 1969, then he noticed significance increase in the level of Hb A1c in diabetes . Another cross sectional study conducted
later by Rahbar et al.  at Tehran University found a similar abnormality in 57 diabetic patients.
After that discovery, numerous small studies were conducted correlating the Hb A1c level to the blood glucose level resulting in the idea that Hb A1c could be used as a positive objective factor to measure the glycaemic control. In a larger study of diabetic patients, Trivelli et al.  found a two-fold increase of Hb A1c over values observed in non-diabetic subjects. Thus, by the mid 1970s, it was clear that Hb A1c was elevated in humans with diabetes mellitus, although the mechanism of this abnormality was not understood. In 1976 Koenig et al.  proposed the idea to use HbA1c level for monitoring the degree of control of glucose metabolism in diabetic patients and described. HbA1c as a useful mean for monitoring the glycaemic
control in diabetic patients. Hb A1c was introduced into clinical
use in the 1980s and subsequently has become an important test
in Clinical practice . Different studies have shown variation
in the normal ranges of Hb A1c.
In Brazil, Buffarini et al.  performed a two cohort studies
in 1982and 1993 which were published later in 2016. It aimed at
describing the distribution of Hb A1c levels according to earlylife
and contemporary factors in adolescents and adults without
diabetes mellitus and found the distribution of the Hb A1c was
approximately 5.10% (±0.43), and 4.89% (±0.50) respectively.
In United Kingdom in 1989, Simon et al.  reported the
distribution of Hb A1c in 3240 healthy adult population. They
found that the approximately normal distribution of Hb A1c was
5.03% (±0.53). In England at 2001 Gulliford and Ukoumunne
performed a Cross-sectional survey and found a mean Hb A1c
of 6.34% (±0.85) in a general population of 9,772 non-diabetic,
white European subjects aged 16 years and older . In 2010
Ghazanfari et al.  in Iran performed a study to measure the
association between Hb A1c and Fasting Blood Sugar (FBS)
through a cross-sectional population-based study, and found
the mean of Hb A1c in non-diabetics was 5.61 %(±0.73) and in
diabetics was7.88% (±1.92).
In 2011 Nathan et al. in UK reported the normal range of Hb
A1c for non diabetic people was found to be between 3.6 – 5.5 %
. According to a report published in 2009 by an International
Expert Committee on the role of Hb A1c in the diagnosis of
diabetes, Hb A1c can be used to diagnose diabetes and that the
diagnosis can be made if the Hb A1c level is 6.5% or more and
Hb A1c level below 6% is considered normal , although in
Iran Hb A1c in diabetics was found to be 7.88 % (±1.92) .
Hb A1c results in the UK have usually been aligned to the assay
used in the Diabetes Control and Complications Trial (DCCT),
expressed as a percentage (DCCT-Hb A1c)-non-diabetic ‘normal’
range being 4-6% [19,20]. Diagnostic criteria for diabetes that
made by (WHO report 2011) determined that Hb A1c of 6.5%
was considered as the cut-off point for diagnosing diabetes.
A value <6.5% does not exclude diabetes diagnosed using
glucose tests. Faerch et al. & Gulliford et al. [15,21] both found
somewhat higher levels of Hb A1c in men compared to women,
but other studies found no sex-related differences in Hb A1c
[22,23]. According to report published by the international
diabetes fedaration- The IDF - Middle East and North Africa
(MENA), there was over 1.4 million cases of diabetes in Sudan
in 2015 . Although the HbA1c reference intervals for the
general population in western countries are well established,
reference intervals for healthy Sudanese people are not clearly
defined. Most of the studies about Hb A1c that conducted in
Sudan was pilot studies that done in small samples or studies
considering abnormal Hb A1c such as Hb A1c in Diabetes
Mellitus, anemia, pregnancy, or patient with abnormal Hb
structure. These abnormal values of Hb A1c were compared to
the international normal one.
It is well known that the normal values used in Sudanese
laboratories are mainly derived from European studies.
Differences in the normal values in Sudan have been documented
in some hematological values  and respiratory function tests
parameters . As Hb A1c is now used largely for DM control,
the normal values of Hb A1c in Sudanese must be established
for the clinical diagnosis and followup of DM. In Khartoum state
at 2016 Ali et al. performed a Cross-sectional study on 20 nondiabetic
adult males of ages between 35-45 years and found a
mean Hb A1c of 3.8 % ±1.17 with a range of (1.2%-5.4 %) .
Another cross-sectional study also done in Khartoum state at
2016 by Fadul et al.  on 20 non-diabetic adult females, their
ages was between 35-45 years and found a mean Hb A1c of 3.43
% ±1.17 with a range of (1.4-5.3%). Despite this variation the
normal level of Hb A1c was generally taken as less than 6% and
these values were applied to diabetic patients in Sudan, could
there be a difference in the normal level of Hb A1c in Sudanese
population is clearly a valid a question.
In this study, the normal level in healthy Sudanese people
will be investigated. Most of the studies about normal Hb A1c
were obtained in Western countries. These countries have
totally different environment, ethnic groups, nutritional habits
and body mass index, compared to Sudan. Currently, there are
no known big scale studies conducted to investigate the normal
reference range of Hb A1c in Sudanese people, and the normal
reference range of Hb A1c in Sudanese hospitals and clinics
is obtained from non-Sudanese subjects depending on the
international American and British Guidelines.
A Cross sectional study conducted in Khartoum state capital
of Sudan between 2016-2018 on Healthy Sudanese subjects of
both sexes with age group 20 -60 years. 444 Sudanese adult
volunteers were included – 91 males, 353 were females. All
subjects had normal fasting blood glucose (FBG). The exclusion
criteria of this study include Pregnant ladies , abnormal FBG ,
Diabetes mellitus, Hypertension , Renal failure, Liver disease,
Cancer, Chronic diseases (cardiac diseases, TB, asthma,
thyroid disorders), Hematological disorders., Recent acute
diseases (Malaria, typhoid fever …etc), Lactation, History of
recent surgery (splenectomy), History of schistosomiasis and
Subjects not consenting. Written consents were obtained from
all participants after fully explaining to them the project. A
questionnaire was filled by all volunteers to obtain the data
about name, age, address, medical history, drug use, and lifestyle.
Weight, height, and blood pressure were measured with
standard techniques. Complete clinical examination was
performed. After informed consent, five ml of venous blood
was collected by a standard procedure from each participant under complete aseptic conditions in the morning and after
an overnight fasting. 2.5ml was placed in fluoride oxalate
containers, and then used for FBG measurement with auto
analyzer A15. The other 2.5ml was placed in EDTA container
and used for Hb A1c analysis. (Icteric, lipemic, hemolyzed or
bacterially contaminated samples were not used). Hb A1c was
measured using modified ELISA reader known as COPAS Integra
800 using commercial reagent kits from Roche Company. All
techniques and equipment were standardized. All data collected
in this study was analyzed using the SPSS computer programs,
(t-test for mean and p. value P≤0.05 for significance).
Ethical Approval of this study was obtained from the Federal
Ministry of Health in Sudan (FMOH) and The National Ribat
University (NRU). The objectives of the study were explained to
all individuals participating in the study. An informed consent
was obtained from each participant in the study.
In previous pilot studies we have found that HbA 1c level
was lower in sudanese compared to the international values
[27,28]. The result of this study in khartoum state with a bigger
sample has confirmed that the Hb A1c in sudanese is lower than
the international. In this study the normal mean distribution
of HbA1c in Sudanese adult males was 4.2% (±1.8%) and the
range was 1.2-6.5% which is lower than in international range
(3.6-6.5%) [18-20]. These differences may be due to ethnic
and genetic differences because all these comparable studies
were performed in Western countries, although the nutritional
differences need further investigations. This study showed
that the normal mean distribution of Hb A1c is not different
between the males and females which is in contrast to Faerch et
al. & Gulliford et al. [15,21] who found somewhat higher levels
of Hb A1c in men compared to women, but in agreement with
Kilpatrick et al. & Modan et al. [22,23].
These variations can be related to exact physiological role
of Hb A1c which has not been addressed. In conclusion, this
study showed significant variations in the level of Hb A1c of
healthy Sudanese in comparison with the reference ranges of
international parameters. The study results re¬vealed an urgent
need to build national reference ranges for all hematological
and other physiological parameters for Sudanese population
in the near future. Further studies to confirm these results and
establish reference range for Hb A1c in different age groups, Hb
A1c in pregnancy, Hb A1c in different category of BMI, Hb A1c
in different Sudanese tribes and Hb A1c in atheletes are highly