Fasting plasma glucose as a screening test for gestational diabetes mellitus : a hospital-based, cross sectional study of 370 antenatal patients in Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia, 1999-2000
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Date
2002-11
Authors
Mohd Noor, Nor Haznita
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Objective:
To evaluate fasting plasma glucose as a screening test for gestational diabetes mellitus.
Further objectives were to determine demographic distribution of gestational diabetes
mellitus and to assess the proportions of gestational diabetes mellitus picked up by
selective screening using historical risk factors alone.
Methods:
A hospital-based, cross-sectional study was carried out at University Hospital,
Universiti Sains Malaysia (HUSM), Kubang Kerian, Kelantan, from July 1999 till
October 2000. Baseline data from 461 women who agreed to participate in the study
with gestational ages less than 28 weeks and no previous diagnosis of diabetes were
collected. A standardized 2-h 75-g oral glucose tolerance test was performed in 370
women. Gestational diabetes and its subcategories-diabetes and gestational impaired
glucose tolerance-were defined according to the Definition, Diagnosis and
Classification ofDiabetes Mellitus and its Complications. Part !:Diagnosis and
Classification of Diabetes Mellitus Provisional Report of a WHO Consultation.
Screening properties of fasting plasma glucose were evaluated by calculating
sensitivity and specificity with receiver operator characteristic curves.
Results:
In this study, fasting plasma glucose level of~7.0 mmol/1 has a very low sensitivity
(17.8%) in detecting gestational diabetes mellitus as a whole. The sensitivity (62.5%)
improves if the cut-off level is used to detect subcategory gestational diabetes mellitus.
However, fasting plasma glucose level of'?:.7.0 mmoVl is highly specific (>98%) in
detecting both conditions. Impaired fasting glucose or IFG was found to have
sensitivity of only 1. 8% and specificity of 97.1% in detecting subcategory gestational
impaired glucose tolerance.
Based on this study, fasting plasma glucose of 4.4 mmol/1 or more is able to reach a
sensitivity of75.3% and a specificity of66.3% in detection ofGDM as a whole.
Taking 4.3 mmol/1 as the upper limit of normal and 7.0 mmol/1 or more as confirmed
gestational diabetes mellitus, oral glucose testing in 61.9% of patients could be
eliminated. By using this strategy, 19 or 5.1% were misclassified with 18 or 4.9%
being false negative.
Advancing age was significantly associated with increase incidence of GDM.
Although the proportions of patients who were grandmultiparous and great
grandmultiparous (25 .1%) were high, it was not shown to be significantly associated
with GDM. Majority of those diagnosed as GDM were Malay as majority of patients
in this study were Malay. Although slight increase in incidence of GDM were shown
with increase BMI in this study but it was not statistically significant. There was also
no significant difference in incidence of GDM among various income groups.
Using historical factors as a screening, 45.3% of normal patients were noted to have
one or more risk factor for developing GDM, which means that nearly half of normal
or 36.4% of all patients would undergo unnecessary oral glucose testing. Furthermore,
30.1% ofGDM without a risk factor would be totally missed out.
detecting both conditions. Impaired fasting glucose or IFG was found to have
sensitivity of only 1. 8% and specificity of 97.1% in detecting subcategory gestational
impaired glucose tolerance.
Based on this study, fasting plasma glucose of 4.4 mmol/1 or more is able to reach a
sensitivity of75.3% and a specificity of66.3% in detection ofGDM as a whole.
Taking 4.3 mmoVI as the upper limit of normal and 7.0 mmol/1 or more as confirmed
gestational diabetes mellitus, oral glucose testing in 61.9% of patients could be
eliminated. By using this strategy, 19 or 5.1% were misclassified with 18 or 4. 9%
being false negative.
Advancing age was significantly associated with increase incidence of GDM.
Although the proportions of patients who were grandmultiparous and great
grandmultiparous (25.1 %) were high, it was not shown to be significantly associated
with GDM. Majority of those diagnosed as GDM were Malay as majority of patients
in this study were Malay. Although slight increase in incidence of GDM were shown
with increase BMI in this study but it was not statistically significant. There was also
no significant difference in incidence of GDM among various income groups.
Using historical factors as a screening, 45.3% of normal patients were noted to have
one or more risk factor for developing GDM, which means that nearly half of normal
or 36.4% of all patients would undergo unnecessary oral glucose testing. Furthermore,
30.1% ofGDM without a risk factor would be totally missed out.
Conclusions:
While previously neglected as a screening test for GDM, in our population the FPG
offers a potentially simple, practical algorithm to screen for GDM by being costeffective
and patient friendly.
Description
Keywords
Fasting plasma glucose