VOLUME 8 NUMBER 3 • SEPTEMBER 2011
111
SA JOURNAL OF DIABETES & VASCULAR DISEASE
ACHIEVING BEST PRACTICE
Key messages
MPV in pregnancy may:
• indicate future CVD risk
• improve follow up of women with GDM and GIGT.
Diabetes is an established risk factor for CVD; therefore, the
subset of women with GDM who develop type 2 diabetes mellitus
are at an increased risk of developing CVD in the future.
8,9
It is
uncertain, however, whether normoglycaemic women with a history
of GDM or GIGT who do not develop type 2 diabetes mellitus later
are also at increased risk of future CVD.
Women with a history of GDM, although normoglycaemic
after pregnancy, have increased insulin resistance and decreased
endothelium-dependent vasodilation.
28,29
Such data suggest that
GDM may represent the transient unmasking of a latent metabolic
syndrome that may become clinically apparent later in life as CVD.
Vascular dysfunction is another independent risk factor for CVD
andwomenwith prior GDMmay have impaired vascular function.
30,31
In their study, Anastasiou
et al
.
29
concluded that women with a
history of GDM have impaired endothelial function as assessed by
flow-mediated dilatation. Another study on this issue
31
showed that
women with prior GDM have impaired acetylcholine-induced skin
vasodilatation after the postpartum period (2–4 years), assessed
by laser Doppler flow, when compared with normal controls. The
changed balance between prostacyclin and thromboxane observed
in vessels of diabetic patients might serve as an explanation for the
vascular modifications mentioned above.
32
This imbalance between
prostacyclin and thromboxane is responsible for hypercoagulability
in diabetic patients and could result in foetal loss – one of the most
important complications of GDM. Hypercoagulability and vascular
dysfunction cause microthrombosis on placental bed vessels and
placental infarctions. Consequently, this generates an impairment
in the foetomaternal circulatory system, that results in low placental
perfusion and finally in the loss of the foetus.
33
Platelets play an important role in the integrity of normal
homeostasis, and MPV is the indicator for their function.
34
The
large platelets contain more dense granules, are more potent than
the smaller platelets, and are hence more thrombogenic.
35-37
An
increase in MPV has been documented in patients with metabolic
syndrome, stroke and diabetes mellitus.
36
Increased MPV is now
emerging as an independent risk factor for thromboembolism and
MI.
13,14,38,39
Yin
et al
.
40
compared platelet counts and MPV values for
pregnant women with GDM in the last trimester with the values for
healthy pregnant women. Women with GDM were found to have
a lower platelet count on average and a higher MPV. Nevertheless,
this finding was not statistically significant.
Bozkurt
et al
.
41
demonstrated that the MPV of their GDM group
was significantly higher than the MPV of healthy pregnant women,
but no statistically significant difference was observed in the
platelet count between the GDM and normal pregnant women.
Additionally, an inverse relationship was observed between platelet
number and MPV. We found similar results to Bozkurt
et al
. GDM
cases had a lower platelet count on average and a higher MPV.
There was no difference between groups in terms of platelet count,
but the MPV of our GDM group was significantly higher than the
healthy group. An inverse relationship between platelet count and
MPV levels was also observed. This knowledge may be important
for prevention of thrombotic complications related to increased
MPV in patients with GDM that can result in impairment in the
foetomaternal circulatory system. Anticoagulant therapy such as
low-dose aspirin may improve pregnancy outcome by blocking the
action of cyclo-oxygenase in platelets, thereby inhibiting platelet
thromboxane synthesis and preventing thrombosis of the placental
vasculature.
There is a relationship between MPV values and blood glucose
levels. MPV changes with alteration of blood glucose and can be
used as an effective marker for blood glucose level.
42
In a study
group of 22 patients with diabetes mellitus, MPV values were
found to be higher initially, but with the decrease of blood glucose,
a significant decrease in MPV values was also observed.
42
De Pablos-Velasco
et al
.
43
showed that patients with GIGT had
higher prevalence of certain cardiovascular risk factors than patients
with normal glucose tolerance in a white population. In our study
MPV was found to be increased in the GIGT group. Although this
increase was not statistically significant, it may be an early sign of
risk for future CVD.
Conclusion
Glucose intolerance during pregnancy may be an early sign of
metabolic disease later in life. Becoming pregnant is a good challenge
for women to assess their metabolic state. Because pregnancy itself
contains excessive metabolic changes, women who tolerate these
changes successfully (healthy pregnant women) can be accepted as
having a lower CVD risk for the future if no other risk factors are
present. Women with GDM would be expected to be at greater
risk of future CVD. Our findings suggest that GDM may serve as a
marker of increased risk for future CVD.
Another important finding in our study was the presence of
higher MPV in GIGT than in normal OGl cases. This means that
GIGT may be a risk factor for CVD also. Because MPV in GIGT was
only slightly elevated and the increase not statistically significant, we
concluded that the risk for MPV-related CVD and thromboembolism
was not considerably elevated.
The MPV value can contribute to improvement of follow up
and management of GDM and GIGT. It may aid in decreasing the
complications of glucose intolerance and insulin resistance through
early realisation of future CVD risk. Further studies with larger series
and long-term follow up of these cases are needed to confirm this
evidence. Such evidence might lead women to take preventive
measures now and in the future, such as lifestyle changes or
prophylactic pharmacological interventions.
References
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Jimenez-Moleon JJ, Bueno-Cavanillas A, Luna-Del-Castillo JD,
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