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REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
56
VOLUME 8 NUMBER 2 • JUNE 2011
• treatment modalities that may be used during pregnancy (diet
and hypoglycaemic agents)
2
• antenatal care plan
• intrapartum management and possible complications, e.g. LGA
baby
• postnatal management, including a six-week postnatal oral
glucose-tolerance test (OGTT) to exclude type 2 diabetes
• possibility of transient neonatal admission.
2
Diet:
The aims of dietary management are: optimising glycaemic
control,
2
preventing large variations in blood glucose levels, and
providing sufficient nutrition to facilitate appropriate foetal growth.
2
Patients with a BMI
≥
27 kg/m
2
should be advised to reduce
their caloric intake to
≤
25 kCal/kg/day.
2
Moderate exercise (e.g.
brisk walking) should be done for at least 30 minutes daily. Care
should be taken in patients where exercise may be hazardous. The
targeted glycaemic levels are:
• fasting level of 3.5 to 5.9 mmol/l
2
• two-hour postprandial level of
<
7.0 mmol/l.
18
The NICE guideline does advise a one-hour postprandial level of
≤
7.8 mmol/l.
2
It is particularly important to control postprandial
blood glucose levels to prevent adverse pregnancy outcomes.
It is important to note that NICE advises that the HbA
1c
level
should not be routinely used for assessing the glycaemic control in
the second and third trimesters.
2
The IADPSG strategy does utilise
the HbA
1c
level for the diagnosis of overt diabetes in pregnancy.
12
Hypoglycaemic agents:
Should lifestyle modification and dietary
measures fail to optimise glycaemic control, then hypoglycaemic
agents are required. Approximately 10 to 20% of GDM patients
will require either oral hypoglycaemics or insulin therapy.
2
These are
outlined below under the treatment of diabetes in pregnancy.
Pre-existing diabetes in pregnancy
Preconception care
Preconception care has evolved over the last four decades.
19
It has
resulted in women with pre-existing diabetes having improved
peri-natal outcomes. What is concerning is that less than 33%
of pre-existing diabetics get preconception care.
19,20
This results
in persistently poor peri-natal outcomes for these patients, with
increased peri-natal mortality (four-fold increase)
19
and increased
congenital malformations.
19
Most preconception clinics have been reduced from a large
multidisciplinary team to a small team involving only a physician
and a specialist diabetic nurse educator.
19
The obstetric involvement
is minimal. The current aims of preconception care should be
inclusivity, especially participation of the woman and her partner in
decision-making regarding the pregnancy
19
Dietary supplements should be administered during pregnancy
in all diabetic patients – especially folic acid 5 mg daily until the end
of 12 weeks to reduce the incidence of neural tube defects. There
should also be a modification of medication to reduce the risk of
teratogen exposure.
19
Type 2 diabetics have been shown to have
poorer preconception care attendance than type 1 diabetics.
It is not possible to definitively state that preconception care
reduces the risk of spontaneous miscarriages.
19
Pre-term birth in
diabetics has not been reduced following preconception care.
19
The site of care (inpatient or outpatient) has shown no difference
between the two sites with regard to improved peri-natal outcome.
19
There are large cost savings to be gained from preconception care
in that the costs for providing this service are less than the total
costs of adverse pregnancy outcomes.
21
Patients with optimal HbA
1c
levels (
<
6.5%) can be advised to
conceive. Pregnancy is strongly discouraged if HbA
1c
>
10%.
19
Diet
The dietary requirements as outlined above under GDM should be
applied. There should also be vitamin D supplementation in the
obese pregnant diabetic patient. It is important to note that weight
loss is not advised for obese pregnant women.
4
Weight gain is important to control as excessive weight gain
has been associated with adverse pregnancy outcomes.
4
The
recommendations for weight gain in pregnancy (as recommended
by the Institute of Medicine) are in Table 3.
4,22
Hypoglycaemic agents
Hypoglycaemic therapy needs to be initiated in patients with GDM
where exercise and diet have failed to obtain satisfactory glycaemia
within seven to 14 days.
2
Oral hypoglycaemic agents
: the drugs that have been extensively
researched are second-generation sulphonylureas (glyburide
and glibenclamide) and the biguanide metformin. These are the
most commonly used drugs in pregnancy. There are few data
recommending the safe utilisation of other drugs such as the
glitinides and thiazolinediones.
23
The MiG trial has shown that the peri-natal outcomes for
metformin are no different from those achieved by utilising insulin.
It was also found, not surprisingly, that the women in this trial
preferred oral metformin to insulin therapy.
24
Rowan
et al
. have
shown that target blood sugar levels may be lower than previously
thought.
25
The lowest complication rates were found with a pre-
prandial level
<
4.9 mmol/l (capillary) and post-prandial
<
6.5
mmol/l (capillary).
25
Similar outcomes (maternal and clinical) were
demonstrated by Dhulkotia
et al
. in their meta-analysis of insulin
and oral hypoglycaemic agents.
26
Caution does need to be exercised with regard to the use of oral
hypoglycaemic agents in pregnancy as there are ‘no randomised
controlled trials of oral agents versus insulin on long-term outcomes
of GDM in pregnancy’.
14
In certain centres locally, there appears to
be limited or no use of oral hypoglycaemics in pregnancy. Local trials
in South Africa (preferably randomised, controlled) are required to
guide the management of pregnant diabetic women.
Insulin therapy:
the optimal therapy for achieving normoglycaemia
in pregnancy is insulin therapy.
27
The goals of the insulin therapy
regimen decided upon should be to address two issues, namely,
the external source of glucose (food), and endogenous glucose
(hepatic).
27
This is the basis for the basal bolus dose regimen – a
combination of a rapid-acting insulin (for postprandial control) and
Table 3.
Institute of Medicine Recommendations for weight gain in
pregnancy.
4,22
Pre-pregnancy BMI
(kg/m
2
)
Total weight gain
range (kg)
Mean weight gain in
2nd and 3rd trimester
(kg/week)
Underweight (< 18.5)
12.5–18
0.51
Normal (18.5–24.9)
11.5–16
0.42
Overweight (25–29.9)
7–11.5
0.28
