Amniotic fluid insulin levels identify the fetus at risk of neonatal hypoglycaemia

Is There a Correlation between Apelin and Insulin Concentrations in Early Second Trimester Amniotic Fluid with Fetal Growth Disorders?

INTRODUCTION

Fetal growth disturbances place fetuses at increased risk for perinatal morbidity and mortality. As yet, little is known about the basic pathogenetic mechanisms underlying deranged fetal growth. Apelin is an adipokine with several biological activities. Over the past decade, it has been investigated for its possible role in fetal growth restriction. Most studies have examined apelin concentrations in maternal serum and amniotic fluid in the third trimester or during neonatal life. In this study, apelin concentrations were examined for the first time in early second-trimester fetuses. Another major regulator of tissue growth and metabolism is insulin.

MATERIALS AND METHODS

This was a prospective observational cohort study. We measured apelin and insulin concentrations in the amniotic fluid of 80 pregnant women who underwent amniocentesis in the early second trimester. Amniotic fluid samples were stored in appropriate conditions until delivery. The study groups were then defined, i.e., gestations with different fetal growth patterns (SGA, AGA, and LGA). Measurements were made using ELISA kits.

RESULTS

Apelin and insulin levels were measured in all 80 samples. The analysis revealed statistically significant differences in apelin concentrations among groups (p = 0.007). Apelin concentrations in large for gestational age (LGA) fetuses were significantly lower compared to those in AGA and SGA fetuses. Insulin concentrations did not differ significantly among groups.

CONCLUSIONS

A clear trend towards decreasing apelin concentrations as birthweight progressively increased was identified. Amniotic fluid apelin concentrations in the early second trimester may be useful as a predictive factor for determining the risk of a fetus being born LGA. Future studies are expected/needed to corroborate the present findings and should ideally focus on the potential interplay of apelin with other known intrauterine metabolic factors.

Biomarkers for Macrosomia Prediction in Pregnancies Affected by Diabetes

Large birthweight, or macrosomia, is one of the commonest complications for pregnancies affected by diabetes. As macrosomia is associated with an increased risk of a number of adverse outcomes for both the mother and offspring, accurate antenatal prediction of fetal macrosomia could be beneficial in guiding appropriate models of care and interventions that may avoid or reduce these associated risks. However, current prediction strategies which include physical examination and ultrasound assessment, are imprecise. Biomarkers are proving useful in various specialties and may offer a new avenue for improved prediction of macrosomia. Prime biomarker candidates in pregnancies with diabetes include maternal glycaemic markers (glucose, 1,5-anhydroglucitol, glycosylated hemoglobin) and hormones proposed implicated in placental nutrient transfer (adiponectin and insulin-like growth factor-1). There is some support for an association of these biomarkers with birthweight and/or macrosomia, although current evidence in this emerging field is still limited. Thus, although biomarkers hold promise, further investigation is needed to elucidate the potential clinical utility of biomarkers for macrosomia prediction for pregnancies affected by diabetes.

Maternal physical activity before and during early pregnancy as a risk factor for gestational diabetes mellitus

The aim of this study was to assess whether the levels of physical activity before and during early pregnancy are associated with the prevalence of gestational diabetes mellitus (GDM). The study group included 160 puerperas. Among them, 40 (25%) diagnosed as having GDM during their recent pregnancy, whereas the remaining 120 (75%) served as controls. The international physical activity questionnaire (IPAQ-Greek version) was applied twice, in an attempt to estimate the level of physical activity before and during early pregnancy. Women who were "inactive" before or during early pregnancy had odds ratio (OR) 7.9 [95% confidence interval (CI) 3.7-16.56] and 1.3 (95% CI 1.2-1.4) of developing GDM, compared to "minimally active" or "active" women, respectively. Pregnancy resulted in a decrease in the level of physical activity (P < 0.005) during early pregnancy, independently of the diagnosis of GDM and morbidity during early pregnancy. We conclude that physical inactivity before and during early pregnancy is associated with increased risk for developing GDM in late pregnancy.

Gestational diabetes mellitus: developments in diagnosis and treatment

After many years of uncertainty regarding the true pathological nature of mild gestational diabetes and the possible benefits of treatment, the situation appears to have been resolved by the publication of the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS). It is now appropriate for obstetric units to review their treatment and screening programs for gestational diabetes mellitus. Furthermore, with the publication of the Metformin in Gestational Diabetes (MiG) trial, consideration should be given as to whether metformin should be the first choice when diet fails to maintain glycemic control.

Management of diabetes in pregnancy: comparison of guidelines with current practice at Austrian and Australian obstetric center

AIM

To compare Austrian and Australian national guidelines for gestational and pre-gestational diabetes and estimate the level to which physicians comply with their country's guidelines.

METHODS

Austrian (ODG, Austrian Diabetes Society) and Australian guidelines (ADIPS, Australasian Diabetes in Pregnancy Society) for the treatment of gestational diabetes and pre-gestational diabetes were systematically reviewed. Current practices in two obstetric centers in Austria and Australia were assessed by interviewing key stakeholders through questionnaires assessing different components of diabetes care. For gestational diabetes, these components were screening, abnormal oral glucose tolerance test values (mmol/L), abnormal values for diagnosis, further management when abnormal values are detected, monitoring/glucose targets (mmol/L), further management and indications for insulin therapy, route and timing of delivery, and postpartum management and counseling. For pre-gestational diabetes, the components were management during the preconceptional period, glucose target values, medical surveillance, obstetric surveillance, medication used, route and timing of delivery, and postpartum management and counseling.

RESULTS

More variation was found in the management of gestational than pre-gestational diabetes. There were differences in oral glucose tolerance test and cut-off levels for diagnosing gestational diabetes in both centers and guidelines. Australian guidelines recommended two-stage screening for gestational diabetes, while Austrian guidelines recommended one-stage screening. At the Austrian obstetric center, amniocentesis was recommended for determining the start of insulin treatment in pregnant women with gestational diabetes. This approach was neither used at the Australian obstetric center nor recommended by any of the two guidelines.

CONCLUSION

Our study showed that it was difficult to standardize screening criteria and diagnostic methods for gestational and pre-gestational diabetes. National and international consensus has yet to be achieved in the management of diabetes in pregnancy.

Urinary excretion of inositol phosphoglycan P-type in gestational diabetes mellitus

OBJECTIVE

The mechanisms underlying insulin resistance during normal pregnancy, and its further exacerbation in pregnancies complicated by gestational diabetes mellitus (GDM), are generally unknown. Inositolphosphoglycan P-type (P-IPG), a putative second messenger of insulin, correlates with the degree of insulin resistance in diabetic subjects. An increase during normal pregnancy, in maternal and fetal compartments, has recently been reported.

METHODS

A cross-sectional study was carried out in 48 women with GDM and 23 healthy pregnant women. Urinary levels of P-IPG were assessed spectrophotometrically by the activation of pyruvate dehydrogenase phosphatase in urinary specimens and correlated with clinical parameters.

RESULTS

Urinary excretion of P-IPG was higher in GDM than in control women (312.1 +/- 151.0 vs. 210.6 +/- 82.7 nmol NADH/min/mg creatinine, P < 0.01) with values increasing throughout pregnancy in control subjects (r2 = 0.34, P < 0.01). P-IPG correlated with blood glucose levels (r(2) = 0.39, P < 0.01 for postprandial glycaemia and r2 = 0.18 P < 0.01 for mean glycaemia) and birthweight in the diabetic group (r2 = 0.14, P < 0.01).

CONCLUSIONS

Increased P-IPG urinary excretion occurs in GDM and positively correlates with blood glucose levels. P-IPG may play a role in maternal glycaemic control and, possibly, fetal growth in GDM.

Gestational Diabetes: A Review of the Current Literature and Guidelines

Despite large numbers of original research studies spanning 4 decades there is still no consensus on the subject of gestational diabetes. Should all pregnant women be screened or only those with risk factors? Or is it safe not to screen at all? Which screening test and which diagnostic test are the most reliable? Which cutoff values should we use? What are the risks involved for mother and baby and can treatment improve outcome? What is the connection between gestational diabetes and diabetes mellitus type II? Are there disadvantages to screening? A review of relevant articles shows that definitive answers to these questions are not yet available. There is no gold standard screening test and no threshold glucose value above which complications are markedly increased. On the contrary, there appears to be a continuum of slowly increasing risks with rising blood glucose values, where it seems difficult to draw a clear line between pathology and physiology. Moreover, treatment has thus far not been shown to significantly improve outcome. There seems to be an indistinct area between the diagnosis of gestational diabetes and diabetes mellitus type II, where women with risk factors for one are also predisposed to develop the other, thereby confusing the diagnosis. Finally, the disadvantages to diagnosing and treating women without a clearly proven benefit seem to be significant. Therefore it seems defensible to suspend all screening and treatment for gestational diabetes, or at least significantly raise the threshold for making a positive diagnosis and initiating treatment, until further research has proven a clear benefit.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize that there is still no worldwide consensus on the diagnosis, management, and adverse effects of Gestational Diabetes Mellitus (GDM); explain that all methods of screening vary in sensitivity and depend on very strict preparations for screening; state that there is no agreement on ideal levels of blood glucose to prevent untoward effects; and recall that there are two very large prospective studies that clarify the dark waters and that we should await their results.

Can ultrasound fetal biometry predict fetal hyperinsulinaemia at delivery in pregnancy complicated by maternal diabetes?

OBJECTIVE

The aim of this study was to determine whether there is an association between ultrasound fetal biometry and amniotic fluid insulin levels at delivery in women with pre-existing diabetes or impaired glucose tolerance in pregnancy.

STUDY DESIGN

This retrospective cohort study identified 93 women who had amniotic fluid insulin levels measured at time of delivery. Standardised estimated fetal weight and fetal growth velocity were calculated from serial third trimester fetal ultrasound measurements.

RESULTS

Women with pre-existing diabetes had significantly greater mean growth velocity [1.39 (95% CI: 0.43-2.23) versus 0.39 (95% CI: -01.7-0.95); p=0.04], significantly greater mean estimated fetal weight (EFW) Z score prior to delivery [2.36 (95% CI: 1.82-2.9) versus 1.38 (95% CI: 1.02-1.74); p=0.002] and greater mean birthweight centile [82 (95% CI: 0.74-0.89) versus 67 (95% CI: 58-76); p=0.02] than those with GDM/IGT. Amniotic fluid insulin levels demonstrated a similar significant difference between the pre-existing and GDM/IGT groups [20.5 (95% CI: 12.9-28.1) versus 8.5 (95% CI: 5.4-11.7); p=0.001]. An association between fetal growth and size and amniotic fluid insulin was observed in women with pre-existing diabetes. Positive likelihood ratios were 1.67 and 2.08, respectively, for the prediction of liquor insulin greater than the 95th centile in women with pre-existing diabetes.

CONCLUSION

Ultrasound measures of fetal size and growth used in this study are not sufficiently accurate to predict those infants likely to be at risk from the adverse effects of fetal hyperinsulinaemia.

Pregnancy in women with pre-existing diabetes: management issues

Despite significantly increased input from multidisciplinary teams during the antenatal period, pregnancy outcomes for women with type 1 and type 2 diabetes remain substantially worse than that of the general obstetric population. Regarding fetal congenital malformations, these are likely to be preventable only by strategies introduced prior to pregnancy. The relationship between fetal macrosomia and glycaemic control is complex, and reducing the incidence of macrosomia may be possible only by novel management strategies that address the wide fluctuations in blood glucose over a 24-hour period. Irrespective of pregnancy diabetes control, the complication of neonatal hypoglycaemia can largely be avoided by tight control of glucose values during labour and delivery. The continued lack of understanding of the pathophysiology of late fetal death in diabetic pregnancies and the shortcomings of current methods of antenatal fetal surveillance make it likely that infants of diabetic mothers will continue to be delivered preterm, with the attendant implications of neonatal morbidity and cost.

Flexible treatment of Gestational Diabetes modulated on ultrasound evaluation of intrauterine growth: a controlled randomized clinical trial

OBJECTIVES

In order to prevent abnormalities of fetal growth still characterizing pregnancies complicated by Gestational Diabetes (GDM), in the present study we evaluated a therapeutic strategy for GDM based on ultrasound (US) measurement of fetal insulin-sensitive tissues.

METHODS

All GDM women diagnosed before 28th week immediately started diet and self-monitoring of blood glucose; after 2 weeks they were randomized to conventional (C) or modified (M) management. In C the glycemic target (GT) was fixed at 90 fasting/120 post-prandial mg/dl; in M GT varied, according to US measurement of the Abdominal Circumference (AC) centile performed every 2 weeks: 80/100 if AC > or =75th, 100/140 if AC<75th. Therapy was tailored to mean fasting (FG) and postprandial glycemia (PPG).

RESULTS

Globally, 229 women completed the study, 78 in C, 151 in M. Use of insulin was 16.7% in C, 30.4% in M (total groups), significantly more frequent in M than in C (59.7% vs 15.4%) when considering only women with AC > or =75th c. Mean metabolic data were similar in the 2 groups, but in M a tightly-optimized subgroup, resulting from the lowering of GT due to AC > or =75th, coexisted with a less-controlled one, whose higher GT was justified by AC<75th. Pregnancy outcome was better in M, with lower (p<0.05*) rate of LGA* (7.9% vs 17.9%), SGA (6.0% vs 9.0%) and Macrosomia* (3.3% vs 11.5%).

CONCLUSIONS

Our data show the value of a flexible US-based approach to the treatment of GDM. This model does not necessarily involve a generalized aggressive treatment, allowing to concentrate therapeutical efforts on a small subgroup of women showing indirect US evidence of fetal hyperinsulinization. Such a selective approach allowed to obtain a near-normalization of fetal growth, with clear advantages on global pregnancy outcome.

Screening for gestational diabetes mellitus

OBJECTIVE

The purpose of this document is to briefly review the existing data regarding the effect of a diagnosis of gestational diabetes mellitus (GDM), the different screening and diagnostic practices for GDM, and, finally, outline the recommended options for GDM screening in Canada.

OPTIONS

Consideration has been given to the existing screening practices for GDM including universal screening, risk factor-based screening, and the option of not screening for GDM.

OUTCOMES

The short- and long-term maternal-fetal outcomes in GDM were reviewed with emphasis given to examination of the data regarding the effect of diagnosis and treatment of GDM on these outcomes.

EVIDENCE

A comprehensive search of the literature from 1990 through April 2002 using MEDLINE and the Cochrane Database and a review of randomized controlled trials (RCTs) was undertaken. Additional studies and clinical guidelines published outside this time frame but with specific clinical relevance were also reviewed. The level of evidence of the recommendations in this document has been determined using the criteria described by the Canadian Task Force on the Periodic Health Examination.

RECOMMENDATIONS

I. A single approach of testing for GDM cannot be recommended at the present as there is not enough evidence-based data proving the beneficial effect of a large screening program. Until a large prospective RCT shows a clear clinical benefit for screening and consequently treating GDM, recommendations will by necessity be based on consensus or expert opinion. Each of the following approaches is acceptable. a. Routine screening of women at 24-28 weeks of gestation may be recommended with the 50 g glucose challenge test (GCT), using a threshold of 7.8 mmol/L (140 mg/dL), except in those women who fulfill the criteria for low risk, which includes the following: * maternal age < 25 * Caucasian or member of other ethnic group with low prevalence of diabetes * pregnant body mass index (BMI) </= 27 * no previous history of GDM or glucose intolerance * no family history of diabetes in first-degree relative * no history of GDM-associated adverse pregnancy outcomes. The diagnostic test can be the 100 g oral glucose tolerance test (OGTT), as recommended by ACOG, or the 75 g OGTT, according to the American Diabetes Association (ADA) criteria. Use of the World Health Organization (WHO) criteria will approximately double the number of women diagnosed with GDM without an apparent clinical benefit. (III-C) b. A small but significant number of Canadian obstetricians and centres have a policy of non-screening for GDM. Until evidence is available from large RCTs that show a clear benefit from screening for glucose intolerance in pregnancy, the option of not screening for GDM is considered acceptable. Conversely, there are no compelling data to stop screening when it is practiced. (III-C) c. The clinician should consider the recommendation of the Fourth International Workshop-Conference that women considered at high risk for GDM should undergo a diagnostic test as early in pregnancy as possible and that testing should be repeated at 24-28 weeks if initial results are negative. (III-C) d. If GDM is diagnosed, glucose tolerance should be re-assessed with a 75 g OGTT 6-12 weeks postpartum in order to identify women with persistent glucose intolerance. (III-C)2. A large RCT is needed to quantify the advantages and dis-advantages of routine screening for GDM. Furthermore, the need for universally accepted, outcome-based diagnostic criteria for GDM is emphasized. (III-C) VALIDATION: This guideline was reviewed by the SOGC Maternal-Fetal Medicine Committee.

SPONSOR

The Society of Obstetricians and Gynaecologists of Canada.