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ABSTRACT
Objectives:
The aim of this study was to investigate whether
HbA1c testing can be used as a predictor for the
presence of diabetic retinopathy as an example
of long term diabetic complications.
Methods: A prospective
study was conducted at Prince Ali Hospital in
Southern Jordan. 120 diabetic patients attending
internal medicine clinic were investigated for
their HbA1c level. Patients were divided into
four categories according to HbA1c level (more
than 9%, 7 to 9 %, 5 to 7 %, and less than 5%).
Patients were referred to the ophthalmology clinic
and investigated for the presence and severity
of diabetic retinopathy. Inclusion criteria included
patients with type 2 diabetes and duration of
illness of more than 10 years. Patients with other
medical illness were excluded from the study.
Results: The mean
age of patients was 59.3 years. Forty patients
were found to have diabetic retinopathy; thirty
of them had non proliferative changes and ten
had proliferative retinopathy. HbA1c of more than
9% was associated with the most severe form of
retinopathy. The mean duration of diabetes was
11.6 years.
Conclusion: HbA1c
measurement is a useful test for predicting and
monitoring the risk of progression of diabetic
retinopathy as an example of long term diabetic
complications.
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INTRODUCTION
Diabetic retinopathy is the
leading cause of visual disability in the industrialized
countries. Duration of diabetes, type of diabetes, control
of blood sugar, associated systemic conditions, age
and sex are known risk factors associated with retinopathy
and its progression1-3.
The HbA1c, glycated hemoglobin
test, or glycohemoglobin is an important blood test
used to determine how well diabetes is being controlled.
It provides an average of blood glucose control over
a 6 to 12 week period. It is recommended that glycaemic
control be strongly promoted and that HbA1c investigations
routinely carried out4.
The aim of this study was to
investigate whether HbA1c testing can be used as a predictor
for the presence of diabetic retinopathy as an example
of long term diabetic complications.
METHODS
A prospective study was conducted
at Prince Ali Hospital in Southern Jordan. 120 diabetic
patients attending the internal medicine clinic were
investigated for their HbA1c level. Inclusion criteria
included patients with type 2 diabetes and duration
of illness of more than 10 years. Patients were divided
into four categories according to HbA1c level (more
than 9%, 7 to 9 %, 5 to 7 %, and less than 5%). Patients
were referred to the ophthalmology clinic and investigated
for the presence and severity of diabetic retinopathy.
Patients with other medical illness were excluded from
the study.
RESULTS
The mean age of patients was
59.3 years with a mean duration of diabetes of 11.6
years.
Forty patients (33.3%) were found to have diabetic retinopathy;
thirty of them (25%) had non proliferative changes and
10 (8.3%) had proliferative retinopathy. HbA1c of more
than 9% was associated with the most severe form of
retinopathy. Among the 10 patients with proliferative
retinopathy 8 had HbA1c > 9% and 2 had HbA1c between
7 and 9 %. Patients with HbA1c of less than 5% were
not found to have proliferative retinopathy. The 30
patients with non proliferative changes were also found
to have a higher level of HbA1c (Table 1).
Table 1 Number and percentage
of patients with the severity of retinopathy and its
relationship with HbA1c level.
| Stage |
HbA1c
> 9% |
HbA1c
7 - 9% |
HbA1c
5 -7% |
HbA1c
< 5% |
Total |
| Non proliferative
retinopathy |
18
(15%) |
8
(6.7%) |
3
(2.5%) |
1(0.8%) |
30
(25%) |
| Proliferative retinopathy |
8 (6.7%) |
2 (1.7%) |
- |
- |
10 (8.3%) |
| Total |
26 (21.7%) |
10 (8.4%) |
3(2.5%) |
1(0.8%) |
40 (33.3%) |
DISCUSSION
Global projections suggest that
20% of diabetic cases will develop diabetic retinopathy.
Reported factors with high risk of retinopathy are age
of the patient, duration of diabetes, presence of ischemic
heart disease, a high systolic blood pressure, a high
diastolic blood pressure, and an increased level of
fasting capillary glucose level5-6. Patients with type
1 diabetes are known to have higher risk of diabetic
retinopathy than those with type 2 diabetes7. HbA1c
levels of more than 9% have higher rates of diabetic
retinopathy. When diabetes is not controlled, sugar
builds up in the blood and combines with haemoglobin,
becoming "glycated." Therefore, the average
amount of sugar in the blood can be determined by measuring
an HbA1c level. If glucose levels have been high over
recent weeks, HbA1c test will be higher. The amount
of HbA1c will reflect the last several weeks of blood
glucose levels, typically encompassing a period of 120
days8.
For people without diabetes,
the normal range for the HbA1c is between 4% and 6%9. Because studies have repeatedly shown that out-of-control
diabetes results in complications from the disease10-11,
the goal for people with diabetes is an HbA1c less than
7%. This study confirmed that the higher the HbA1c,
the higher the risks of developing diabetic retinopathy.
Patients with HbA1c level of less than 7% were most
likely to have mild retinopathy compared to patients
with HbA1c level of more than 9% who developed the most
severe complications. Patients with HbA1c level between
7-9% were intermediate in risk of progression but did
not significantly differ from those with HbA1c less
than 7%. The conclusion is that patients with levels
above 9% are the group with highest risk of progression.
In conclusion, HbA1c level should
be done routinely for diabetic patients. It is considered
a useful test for predicting and monitoring the risk
of progression of diabetic retinopathy.
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