annual lecture PowerPoint for clinical biochemistry department /j.A. armed forces hospital/Kuwait. 4/8/2021

1. HbA1c Test
Noura Almaslamani
JABER AL-AHMAD ARMED FORCES HOSPITAL
CLINICAL BIOCHEMISTRY DEPARTMENT

2. There are many types of diabetes mellitus,
the common types are:
• D.M type 1 : caused by insulin deficiency, can
develop at any age but occurs most frequently
in children and adolescents.
• D.M type 2 : caused by insulin resistance, more
common in adults.
• Gestational diabetes : occurs in pregnancy due
to abnormality in insulin response.

3. What is a hemoglobin A1c (HbA1c) test?
A hemoglobin A1c (HbA1c) test measures the
amount of blood sugar (glucose) attached to
hemoglobin.
What is hemoglobin?
HB is the red pigmented protein located in
the RBCs, Its main function is to transport
oxygen and carbon dioxide in blood, the RBCs
life span of approximately 100-120 days,
that’s why HbA1c measures the sugar for the
last 3 months .

4. Types of Hemoglobin :
1. Hemoglobin A2 normal range of 1.5–
3.5%.
2. Hemoglobin F (fetal hemoglobin) less
than 0.6% .
3. Hemoglobin A The most common with a
normal amount over 95%
HbA1c represents 70–90% of HbA1,
and is the glycated form of HbA1.

5. HbA1c is formed by the irreversible non enzymatic
reaction of glucose with the N terminal amino group
of the beta-chain of (HbA), The first step is reversible
and yields labile HbA1c, then labile HbA1c is
rearranged to form stable HbA1c in a second
reaction step.

6. Glycated or glycosylated?
• Glycation and glycosylation are two mechanisms which add
(sugars) to the proteins, But glycation is non-enzymatic and
glycosylation is an enzymatic process.
• the sugars added by glycation are Glucose, fructose or galactose
while the sugars added by glycosylation are glycans, mannose or
xylose .

7. Advantages of HbA1c testing over glucose measurement:
1. Reflects the average blood glucose level during the
preceding 2 to 3 months rather than daily variations in
blood glucose levels .
2. Has less biological variability .
3. Used as a diagnostic test for diabetes mellitus and as an
assessment test for glycemic control in people with
diabetes.
4. Predicts the development of diabetic complications in
diabetes patients.
5. Does not require fasting or timed samples.

8. SPECIMEN:
• EDTA whole blood.
• The minimum volume
required for analysis directly
from collection tubes is 1 mL of
whole blood.
• Mix the sample before use.

9. Stability:
• 3 days at 15-25°C.
• 7 days at 2-8°C.
• 6 months at – 15˚ to -25˚C.
• Freeze only once.

10. In our lab we have tow
different machines:
•Cobas c501:
The HbA1c determination is based
on the turbidimetric inhibition
immunoassay (TINIA) for
hemolyzed whole blood.

11. •Tosoh G8:
The HbA1c determination is based on
the HPLC (High performance liquid
chromatography).
The advantage of using HPLC method
is that, it not only provides an A1c
value but also identifies the commonly
occurring hemoglobin variant traits
that can potentially interfere with A1c
results.

12. Reference Interval according to the
American Diabetes Association, are as
follows :
• Hba1c between (20-38 mmol/mol) 4.0-5.6% is
normal.
• HbA1c between (39 -46 mmol/mol) 5.7–6.4% :- is
prediabetes.
• HbA1c greater than or equal to 6.5% (48
mmol/mol) diabetes .
• For patients with diabetes mellitus, the goal of
therapy, in general, is a level below 7.0% (53
mmol/mol).

13. Limitations - interference
1- conditions that change the lifespan of red blood cells (RBC) and
decrease in Hba1c values:
- Patients with Hb variants. (e. g. HbSS, HbCC or HbSC,HbE) .
- Hemolytic anemia(thalassemia trait , homozygous sickle cell trait , other
hemolytic diseases.
- Recent significant or chronic blood loss.
- Pregnancy( Pregnant women exhibit altered RBC kinetics, increased
erythropoiesis and hemodilution).
- Blood donation .
2- Conversely, higher-than-expected levels can be seen in people with a
longer red blood cell lifespan, such as with vitamin B12 or folate
deficiency

14. THANK YOU