Adibah Hanim, Ismail@ Daud
(2008)
Use Of HbA 1 C In The Diagnosis of
Diabetes mellitus Type 2 In High Risk
Patient Attending Outpatient Clinic
(KRK)HUSM.
Universiti Sains Malaysia.
(Submitted)
Abstract
Introduction : For many years diagnosis of diabetes mellitus has dependent primarily
on results of OGTT. Fasting hyperglycaemia, a late manifestation of diabetes is not
generally useful for evaluating the presence or severity of glucose tolerance. OGTT for
the diagnosis of diabetes is inconvenient and require a great deal of patient cooperation. It
is known to be poorly reproducible and is often not performed. To improve patient
compliance with testing, use ofHbA1c to diagnose diabetes has been suggested.
Objectives : To evaluate the use of HbA1c as a diagnostic test for diabetes in high
risk groups attending Klinik Rawatan Keluarga, HUSM. It is also to determine the
sensitivity and specificity of HbA1c as compared to FPG and OGTT to diagnose type 2
diabetes and the optimal cutoff point of HbA 1 c for the diagnosis of type 2 diabetes.
Methodology : This was a cross sectional study conducted from March 2005 to January
2006. Patient age 35 years and above with one or more risk factors for type 2 diabetes
which includes BMI 2: 23, hypertension, history of GDM or big baby (2: 4.0 kg), family
history of diabetes in first degree relatives, hyperlipidaemia and dyslipidaemia, who
consented for the study were included. OGTT and HbAlc were performed in 402
asymptomatic high-risk subjects with positive screen using capillary blood glucose ~
5.6mmol/l. Data was analyzed using SPSS version 11.5.
Result :The mean age and BMI for study samples were 51.6 ±_9.2 and 26.8 ±._ 4.8
respectively. The mean FPG level was 5.6 ± 2.2mmo/l, mean 2h-PP level was 9.6 ±
5.3mmol/l and mean HbA1c was 6.0 ±1.5%. Of 402 patients, 45.3% (n = 182), was
diagnosed as normal glucose tolerance, 22.6% (n = 91) had impaired glucose tolerance or
impaired fasting glucose and 32.1% (n = 129) had diabetes mellitus. Patients with
abnormal glucose tolerance had a higher percentage of HbA 1 c than subjects with normal
glucose tolerance (p< 0.001). HbA1c of 7.0% gave an optimal sensitivity of 81% and
specificity of 91% to predict a FPG of 7.0mmo/l. Whereas; HbA1c of 6.4% with
sensitivity and specificity of 68% and 89% respectively was an optimal value to predict
2h-PP 1l.lmmol/l. Finally, HbA1c of 6.4% gave an optimal sensitivity of 68% and
specificity of90% to predict FPG 7.0mmol/l and/or 2h-PP ll.lm.mol/1.
Conclusion : HbA 1 c measurement in high risk group of patients is a highly specific
test and convenient alternative to fasting plasma glucose or oral glucose tolerance test for
diagnosis oftype 2 diabetes.
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