Discussion
The current study assessed the clinical implications of a low glucose
180 minutes value at the 3-hour OGTT among women with a single
abnormally high OGTT value. It emerged that a suboptimal daily glucose
profile was more prevalent among the women in the study group compared
to women in the control group.
Insulin sensitivity has been shown to decline during pregnancy,
triggering an enhanced insulin release that culminates in euglycemia
after consumption of 100 gr glucose during an OGTT16.
Kuhl et al. reported that women with GDM have impaired first-phase
insulin response which may result in late occurrence of peak plasma
insulin concentrations during an OGTT17. Women with
overly impaired insulin response may experience a delayed peak in
insulin blood levels at 3 hours after glucose consumption and consequent
late hypoglycemia. Thus, hypoglycemia at 3 hours may represent
exceedingly impaired glucose tolerance.
Delibas et al. found an association between reactive hypoglycemia during
an otherwise normal OGTT and adverse perinatal outcome measures, such as
low Apgar scores, low birth weights, and prenatal admission to the
neonatal intensive care unit. 18 Since only women with
a normal OGTT were included, the daily glucose profile was not assessed.
Moreover, the sample size of their study group (pregnant women with
reactive hypoglycemia) was relatively low. We were able to demonstrate a
possible association between late hypoglycemia and compromised glucose
control since our study group included women with a daily glucose
profile that was investigated due to a single abnormal value.
To the best of our knowledge, this is the first study to describe a
possible association between a low glucose result of a 3-hour 100 g
diagnostic OGTT and maternal suboptimal glucose control. Daily glucose
control is affected by multiple factors that are related to insulin
resistance, such as fasting glucose levels during the first trimester,
BMI, gestational weight gain, and previous GDM. We carried out a
multivariate logistic regression analysis in order to assess the effect
of late hypoglycemia evidenced during an OGTT on the glucose profile. As
shown in Fig. 1, hypoglycemia at 3 hours was the only parameter
associated with suboptimal glucose control with an odds ratio of 3.1
(CI, 1.35-7.83). Earlier studies had found associations between first or
second trimester fasting glucose levels and the need for pharmacological
intervention to achieve euglycemia in women with gestational
diabetes19,20. In contrast to those findings, our
study assessed women with a single abnormal value, under strict diet
with similar first trimester fasting glucose values in both study and
control groups. Moreover, as mentioned above, fasting glucose was not
associated with suboptimal glucose control.
We anticipated that suboptimal glucose values would be reflected in the
number of women requiring pharmacological treatment to lower their blood
glucose levels, but the difference between the study and control groups
failed to reach a level of significance. About 10% of the women in the
study group needed insulin compared to 4.4% of the control group
(P =.1). This may be explained by efficient interventions, such as
diet modification and enhanced physical activity, that allowed us to
spare many women with suboptimal glucose control from the need for
treatment. Our study has some limitations that bear mention. First, its
retrospective nature makes it susceptible to selection bias, potential
recording errors, and difficulty in controlling for exposures and
outcomes. This limitation precluded us from arriving at any definitive
conclusion about the impact of late hypoglycemia during the OGTT on
perinatal parameters, we found no significant difference between the
groups in neonatal outcomes, including Apgar scores at 5 and 10 minutes
and prevalence of NICU admission. Additionally, the study was performed
in a single center that treats a relatively homogenous population of
characteristically young and multiparous women, thus generalization of
the findings may be open to question. Finally, the relatively low
numbers of participants prevented us from demonstrating the effect of
late hypoglycemia on the need for pharmacological treatment.
This study revealed a significant association between hypoglycemia at 3
hours after glucose consumption during an OGTT and suboptimal maternal
glycemic control among women with a single abnormally high value in
their OGTT. Stringent follow-up and meticulous glucose control may be
essential for this subgroup of women.
The authors report no conflict of interest.
Contribution to authorship:
Lee Reicher, Anat Lavie, Larissa Feinmesser - Manuscript writing/editing
Sharon Maslovitz, Yariv Yogev, Lee Reicher, - Protocol/project
development
Emmanuel Attali, Relly Reicher, Isca Landesberg - Data collection and
management
Guy Kern -Data analysis
Details of ethics approval: IRB TLV 0273-19 Jan 2019
This research received no specific grant from any funding agency in the
public, commercial, or not-for-profit sectors