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REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
54
VOLUME 8 NUMBER 2 • JUNE 2011
Diabetes care in pregnancy
RR GREEN-THOMPSON
Abstract
T
he incidence of diabetes mellitus has increased
dramatically over the last four decades, particularly
type 2 and gestational diabetes. This is a consequence
of obesity. Great strides have been made in the areas of
diagnosis and management of hyperglycaemia in pregnancy/
gestational diabetes mellitus (GDM), for example the
ACHOIS, MiG and HAPO trials, as well as the IADPSG panel
consensus statement and the NICE, SIGN and ADA guidelines
for the management of diabetes in pregnancy.
The IADPSG statement is a bold step in achieving an
international norm, thereby enabling standard diagnostic
criteria for hyperglycaemia in pregnancy, as well as research
comparisons. Certain oral hypoglycaemic agents have been
shown to be as safe and effective as the mainstay insulin
therapy (in the short term). However, long-term safety
data are lacking. The latter advances have enabled better
pregnancy outcomes as well as improving long-term health
for both mother and baby.
Introduction
Diabetes mellitus is one of the commonest medical problems
affecting South African women. The prevalence of diabetes in the
general South African female population is 3.7%.
1
Worldwide, the
incidence of diabetes among pregnant women is increasing rapidly,
affecting 2 to 5% of pregnant mothers. In developed countries,
pre-existing diabetes accounts for 12.5% and gestational diabetes
for 87.5% of diabetes in pregnancy.
2,3
The epidemic of obesity of
recent decades is rapidly adding to the increased burden of diabetes
in pregnancy, especially type 2 diabetes.
4
The goal of management is euglycaemia or normoglycaemia so
that ‘a pregnancy outcome for women with diabetes that equates
with that of women without diabetes’ is achieved.
5,6
This goal,
however, remains currently out of reach. The great variation in
guidelines and paucity of good evidence further complicates the
management of the pregnant diabetic mother.
The aim of this article is to provide a brief review of the
management of diabetes in pregnancy, concentrating mainly on
gestational diabetes mellitus and its associated controversies.
Pathophysiology of hyperglycaemia in pregnancy
Cellular metabolism requires glucose to meet energy needs. Glucose
is sourced from the diet, glycogenolysis and gluconeogenesis.
7
The metabolic effects of insulin are outlined in Table 1.
7
Pre-
and postprandial glucose levels are controlled by hepatic
gluconeogenesis and glucose uptake by muscle cells, respectively.
Pregnancy is a diabetogenic state. The change in carbohydrate
metabolism results from a decrease in tissue insulin sensitivity.
Insulin resistance results from the increased levels of hormones,
such as human placental lactogen (HPL), cortisol and growth
hormone during pregnancy.
7
Also, some women have pre-existing
insulin resistance [such as obese patients or women with polycystic
ovarian syndrome (PCOS)]. The overall result is an impaired state of
glucose homeostasis. The patients with pre-existing diabetes may
require additional therapy to maintain acceptable glucose levels.
Gestational diabetes (GDM)
There is no clear consensus regarding screening and diagnostic
levels. Even the term gestational diabetes is felt by certain authors
to have ‘outlived its usefulness’.
8
For the purposes of this review,
gestational diabetes is defined as ‘any degree of glucose intolerance
with onset or first recognition during pregnancy’.
9
The controversy regarding the definition has flowed from the
Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) trial,
which demonstrated ‘strong, continuous associations of maternal
glucose levels below those diagnostic of diabetes, with increased
birth weight and increased cord-blood serum C-peptide levels’.
10
This applies to the primary outcomes (birth weight
>
90th percentile,
cord C-peptide
>
90th percentile and primary caesarean delivery) as
well as the secondary outcomes [pre-eclampsia, shoulder dystocia,
neonatal intensive care unit (NICU) admission and pre-term birth].
10
The conclusion is that we healthcare professionals managing
pregnant mothers may have missed many ‘gestational diabetics’
and the associated potentially preventable poor peri-natal
outcomes. The term preferred by certain authors is ‘hyperglycaemia
in pregnancy’ (HGP).
8
Risk factors for GDM
The recognised independent risk factors for gestational diabetes
are:
• obesity (BMI
>
30 kg/m
2
)
• previous macrosomic baby
Correspondence to: RR Green-Thompson
Department of Obstetrics and Gynaecology, Grey’s Hospital, Pietermaritzburg
e-mail: randolph.greenthompson@kznhealth.gov.za
S Afr J Diabetes Vasc Dis
2011;
8
: 54–57.
Table 1.
Insulin metabolic effects
7
Liver
Liver
↓
Glycogenolysis
↑
Glycogen synthesis
↓
Gluconeogenesis
↑
Fat synthesis
↓
Ketogenesis
Adipose
Adipose
↓
Lipolysis
↑
Fat synthesis
↑
Glycerol synthesis
Muscle
Muscle
↓
Protein breakdown
↑
Glucose uptake
↑
Glycogen synthesis
↑
Protein synthesis
