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RESEARCH ARTICLE
SA JOURNAL OF DIABETES & VASCULAR DISEASE
8
VOLUME 18 NUMBER 1 • JULY 2021
for exploring population-specific risk factors other than those
stated in the WHO guidelines or those from high-income countries.
Women attending private hospitals are generally perceived as
having a higher socio-economic status and more likely to adopt
a diet rich in refined foods and a sedentary lifestyle than their
counterparts. By including private ANCs, we anticipated showing
that this group would tend to be more obese and have a higher
risk of developing GDM. Our findings though were contrary to this
expectation as there was no difference in terms of nutritional status
between women from government facilities and those from private
hospitals. Furthermore, women at private ANCs were less likely to
have GDM than those in government hospitals.
Dietary differences between the two groups were not explored
in particular but it appears that the risk that may be conferred
by sedentary habits or a Westernised diet may be balanced by
better health-seeking behaviour and ready access to screening and
diagnostic services in private hospitals.
RBG measurements were largely normal as only three women
had RBG levels > 11.1 mmol/l and 75% of the study population
had an RBG level below 5.5 mmol/l. Other than the RBG test being
an insensitive screening tool, it was also observed on random
questioning that many of the women at the health centres had not
eaten for some time before the measurement, particularly those
who had to leave their homes early in the morning to attend the
clinic on time. Their results may reflect a fasting rather than RBG
level and may explain the large proportion of women with normal
RBG levels. There was no correlation between RBG level and GDM
diagnosed by OGTT or risk factors for GDM. The RBG test may
therefore not be a sensitive screening tool or used as a proxy for
OGTTs in this population.
The prevalence of GDM of 1.6% using WHO criteria was lower
than that described in other African studies using the 1999 WHO
diagnostic criteria (8.8% in South Africa and 13.9% in Nigeria),
11,12
but comparable with what was expected by local obstetricians who
estimated prevalence between 2 and 3% among women attending
ANCs (B Makanani pers commun). GDM was rare, even among
those with traditional risk factors for GDM, suggesting there may
be a unique environmental or genetic influence on risk factors for
GDM in this population.
Using IADPSG criteria, the prevalence of GDM was 12 times
higher compared to WHO criteria and, interestingly, showed a
higher prevalence in government ANCs compared to private ANCs.
We anticipated finding a higher prevalence of GDM using
IADPSG criteria compared to WHO criteria, as has been described
in other studies. There are no other published studies from African
populations for comparison. Many studies have compared prevalence
using the two criteria, with some finding the two to be comparable.
19
The decision to change the criteria depends on performing careful
cost analysis and weighing the risk–benefit ratio, particularly in a
population that is different from the HAPO population.
17,18,26
In a low-
income setting, priority should probably be placed on treating those
diagnosed with GDM based on WHO criteria.
There was a large loss to follow up among the women diagnosed
with GDM, which precludes definitive conclusions on outcome. The
causes of the four miscarriages among the women diagnosed with
GDM were not explored further.
Limitations
The study had several limitations. The study population, being urban,
may have been unrepresentative as it excluded older women in rural
settings likely to have risk factors for GDM. Older and multiparous
women are less likely to attend formal ANCs. Family history of DM
was likely under-reported as most DM in Malawi is undiagnosed.
Loss to follow up precluded making meaningful conclusions on
outcomes on the already small population of women diagnosed
with GDM. Digital instruments used for measuring anthropometric
and biochemical data, including glucometers, BP machines and the
weight scale, although readily accessible for use in the practical sense,
are not always standardised and may be inappropriately calibrated,
which could affect quality and reproducibility of data collected.
Being descriptive, definite causal relationships cannot be
established. A larger prospective study with OGTTs performed on all
women, exploring risk factors for GDM and comparing outcomes
between the WHO and IADPSG criteria would reflect better on the
usefulness of diagnosing GDM in this population.
Conclusion
Using the WHO criteria, GDM was relatively uncommon in women
in Blantyre presenting to ANCs, even among those with traditional
risk factors for GDM. This low prevalence has been demonstrated
in other sub-Saharan countries and we anticipated that the
prevalence would be similar in the Malawian population in general.
The implication of the higher prevalence found when the IADPSG
criteria were used remains to be explored.
Increasing age, parity and being at government hospitals were
associated with GDM in this population. Alternative risk factors
other than the traditional known risk factors need to be explored.
Maintaining optimal weight should be encouraged as this is the
single modifiable risk factor for GDM that was identified in this
study. Should screening for GDM be performed, the RBG test is not
a sensitive screening tool and risk factor-based screening may be
more feasible and cost effective.
Acknowledgements
The authors thank the ANC patients, clinicians and nurses at Queen
Elizabeth Central Hospital, Chilomoni Health Centre, Limbe Health
Centre, Mwaiwathu and Blantyre Adventist hospitals, Mr Henry
Feluzi, Mr Mavuto Mukaka and Miss Elasma Milanzi.
This study was carried out with funding from the World Diabetes
Foundation, grant number WDF 09-451. The funder had no role in
the study design, data collection, analysis, interpretation or writing
the manuscript.
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