Authors: A. PINTIAUX, N. CHABBERT BUFFET, JM. FOIDART
Department of Obstetrics and Gynecology, University of Liège- CHR de la Citadelle
Boulevard du 12 ème de Ligne 1- 4000 LIEGE- This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Keywords : diabetes mellitus, gestational diabetes, pregnancy, HAPO study,  hyperglycemia

Methods for screening, diagnosis and treatment of gestational diabetes have not reached  a consensus so far. The benefits of treatment of this disorder  of glucose tolerance is even denied by some(1).However the impact of gestational diabetes on maternal and fetal health, as well as the positive impact of glucose blood levels control has been increasingly recognized (2, 3, 4)

The criteria for diagnosis of gestational diabetes developed there over 40 years by O'Sullivan and still used until now, had been determined not by the pregnancy outcomes but on the risk of developing diabetes after pregnancy(5) .

The impact of gestational hyperglycemia have finally been confirmed in the largest prospective study ever conducted, the  HAPO study (Hyperglycemia and Adverse Pregnancy Outcomes)(6).

A total of 25 505 pregnant women underwent 75 grams oral glucose-tolerance testing (OGTT) at 24 to 32 weeks of gestation.

Data were unblinded  only in patients whose fasting glucose level was above 105 mg / dl (5.5 mmol / l) and whose  2-hour plasma glucose level was greater than 200 mg / dl (11.1 mmol / l), these values considered as overt diabetes (National Diabetes Data Group criteria).

This study was primarily aimed to observe the impact of maternal blood glucose level on birth weight above the 90th percentile for gestational age , the rate of cesarean section, the occurrence of clinically diagnosed neonatal hypoglycemia and the cord- blood serum C-peptide level above the 90th percentile.

The secondary objective of the study was to correlate the impact of maternal blood glucose to the rate of preeclampsia, premature delivery, shoulder dystocia or birth trauma, neonatal hyperbilirubinemia and neonatal intensive care stay.

The study shows a strong continuous association between maternal glucose level with, increased birth weight, cord- blood serum C-peptide  as well as neonatal adiposity(7, 6, 8, 9).

Trends towards an increase in the prevalence of overweight and obesity, as well as increasing mothers’age are currently observed at least in western countries (10, 11).

Increase in age and overweight, the two main risk factors for diabetes, will further increase  the prevalence of gestational diabetes. In this specific high risk context, it is important to test blood glucose in the first trimester of pregnancy, as early as possible.

First trimester fasting glucose level reviewed in 6000 patients, showed an important and graded relationship with the rate of cesarean, the risk of gestational diabetes and the risk of large-for-gestational-age neonates(12).

The interest of the management of hyperglycemia in pregnancy was enlightened in particular by the ACHOIS (Australian Carbohydrate Intolerance Study in Pregnant Women) trial.

It evaluated prospectively 1000 patients with hyperglycemia below the usual criteria for diabetes and randomly assigned women between 24 and 34 weeks’ gestation to intervention ( dietary advice, blood glucose monitoring and insulin therapy as needed) or routine care.

A significant reduction of severe neonatal complications in the treated group  was observed without cesarean rate increase. Moreover, psychological well-being and quality of maternal life scores were increased. This suggested   the absence of  increase in maternal  anxiey associated to GD care, once diagnosis has been established. Preeclampsia  rates were  also reduced in patients receiving specific care, compared to routine care(2).

The economic analysis of the ACHOIS study  showed evidence of cost-effectiveness as well, (savings of 13 000 UK pounds per avoided serious perinatal event).(13).

Because of the importance of recent publications in the field and the evolution of societal risk of gestational hyperglycemia, a panel of experts met to establish new rules for the diagnosis of hyperglycemia during the pregnancy(14).

As the increase in adverse pregnancy outcomes continuously increase with increasing blood glucose levels  , the role of experts was to define thresholds of blood glucose level beyond which specific care is efficient in reducing maternal and fetal risk.

Early screening showing in the first trimester  fasting plasma glucose (FPG) levels reaching  92 mg / dl (5,1 mmol/l) or over, or hemoglobin A1C greater than or equal to 6.5% or random glucose level greater than or equal to 2 g / l (11,1 mmol/l) should  lead to specific care.

This attitude will allow the diagnosis of preexisting diabetes (type II), early impaired glucose tolerance and  will allow  the organization of early and appropriate care.

The hemoglobin A1C is fully justified to evaluate the level of  pre-gestational  hyperglycemia and will allow us to  adopt an appropriate attitude. Indeed, facing a bad glycaemic control detected early in the  pregnancy, the patient can be informed of the risks of congenital malformation  and will have the opportunity to terminate the pregnancy.

In other cases, intensive management has to be proposed to minimize the risk of hyperglycemia during the first trimester.

We can hope, through this new strategy, to have a real impact on the short-and long-term outcomes of the pregnancy.

In case the  first trimester fasting blood glucose is  under 92 mg / dl (5,1 mmol/l),  a 75 g  oral glucose tolerance test (OGTT) is recommended to be done  between 24 and 28weeks' gestation.

The new pathological thresholds of the OGTT are : fasting plasma glucose greater than or equal to 92 mg / dl (5,1 mmol/l) ; 1 hour plasma glucose greater than or equal to 180 mg / dl ( 10 mmol/l) and 2 hour plasma glucose greater than or equal to 153 mg / dl (8,5 mmol/l). One single pathological value defines gestational hyperglycemia.

Despite advances in knowledge following the ACHOIS and HAPO studies, some key uncertainties remain to be  solved  about    screening, which may be either universal or specific. Currently each physician or care center should choose systematic or personalized screening depending the characteristics of  the corresponding  patient population.

Further information is required from the HAPO study on gestational diabetes usual risk  factors in each glucose category, to allow a choice between universal screening or personalized screening based on risk factors(15). This will also allow a better evaluation of cost effectiveness of screening.

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