Gestational diabetes (GDM) is a potentially serious disorder requiring timely
diagnosis and management to prevent adverse maternal and fetal outcomes.
Of increasing concern today, when treating the woman with GDM, is the need
to provide every woman with an intensive management plan to optimise the
likelihood of favourable pregnancy outcomes. Early identification of those
women with GDM who require insulin therapy in addition to diet therapy would
be beneficial in the planning and standardisation of clinical management
protocols, to enhance pregnancy outcomes and increase cost benefits with
improved allocation of resources.
The aim of this study was to evaluate the ability of the fasting plasma glucose
level (FPG) at diagnosis to predict an increased risk to the fetus and the need
for insulin therapy in a pregnancy complicated by GDM.
A prospective longitudinal study design and recruitment by convenience sample
was used. Data were obtained from 327 women and their babies. Diagnosis of
GDM was made by a 75 gram oral glucose tolerance test (OGTT) using
Australasian Diabetes in Pregnancy Society (ADIPS) criteria with the exception
of seven women diagnosed on a blood glucose level >11.1mmol/l. Following
consent of the women data were collected by a self report questionnaire and
the medical record system at three points; at first intervention, following delivery
and at the postpartum OGTT. Demographic, social, medical, maternal and
neonatal outcome data were collected. The management protocol was similar
for all of the women. Following nutritional intervention any woman who could
not meet the glycemic targets of <= 5mmol/l fasting and/or <= 6.5mmol/l two hours
postprandial was commenced on insulin therapy.
The women had a mean age of 32 years, body mass index (BMI) of 25.7 and
parity of 2 (range 1-12). Diagnosis was made at an average of 30 weeks and
70 women required insulin therapy with a mean dose of 34 IU per day,
commencing at a mean of 31 weeks gestation. Mean birthweight was 3400G.
Of the babies 12% were >4000G. Congenital abnormalities occurred in 3%,
neonatal morbidities in 2% and there was 1 death in utero.
Logistic regression analysis found the following significant associations:
Increasing maternal BMI was related to increasing FPG levels at diagnosis and
the requirement of higher insulin doses. There was a negative linear
relationship to weight gain. Ethnicity was associated with maternal BMI and
ethnicity with BMI was associated with birthweight in the specific ethnic group.
BMI with insulin therapy as a covariate and the FPG value at OGTT were
predictive of persistent glucose intolerance in 14% of women postpartum.
Each value of the OGTT was a significant predictor of the need for insulin
therapy as a function of the week of gestation. The FPG level was the
statistical model of best fit. A 50% probability for requiring insulin was reached
with a FPG at diagnosis of 4.0 mmol/l if tested at 10 weeks gestation, 5.1mmol/l
at 20 weeks and 6.1 mmol/l at 30 weeks (p<.001).
These results support the substantive research aim of the study. The model
has the power to predict the probability (risk) of requiring insulin therapy based
on the maternal FPG level at the OGTT according to the week of gestation.
The study results demonstrate that glucose intolerance is linked to a number of
adverse maternal and fetal outcomes in a continuous and graded fashion. The
degree of reversibility of maternal and fetal risk through therapeutic
interventions such as nutrition therapy, blood glucose monitoring, exercise and
active patient participation aimed at improving glucose tolerance is unknown.
Therefore, the rationale for, and feasibility of, new treatment strategies such as
the application of this statistical model as a management approach require
large scale randomised intervention studies, oriented toward measuring
maternal and fetal outcomes amongst different populations.
| Identifer | oai:union.ndltd.org:ADTP/219476 |
| Date | January 1997 |
| Creators | Wright, Erica, n/a |
| Publisher | University of Canberra. Nursing |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Erica Wright |
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