Impaired glucose tolerance in pregnancy--is it of consequence?

The Relationship between Maternal Gestational Impaired Glucose Tolerance and Risk of Large-for-Gestational-Age Infant: A Meta-Analysis of 14 Studies

OBJECTIVE

To explore, by conducting a meta-analysis, whether gestational impaired glucose tolerance (IGT) is an independent predictor of neonatal large for gestational age (LGA) or not.

METHODS

Medline, Embase, and Cochrane Library databases were searched to identify published epidemiological studies (cohort and case-control studies) investigating the association between gestational IGT and neonatal LGA. Calculations of pooled estimates were conducted in random-effect models or fixed-effects models. Heterogeneity was tested by using chi-square test and I2 statistics. Egger's test (linear regression method) and Begg's test (rank correlation method) were used to assess potential publication bias.

RESULTS

Fourteen observational studies were included in the meta-analysis. The overall risk for the effect of IGT on LGA was 2.09 (1.56, 2.78). Stratified analyses showed no differences regarding different geographic regions or the analysis of overall adjusted odds ratios. No evidence of publication bias was observed in either Egger's test or Begg's test results.

CONCLUSION

Gestational IGT is an independent predictor of neonatal LGA.

The effects of adjuvant insulin therapy among pregnant women with IGT who failed to achieve the desired glycemia levels by diet and moderate physical activity

OBJECTIVE

Evaluation of adjuvant insulin therapy effects on glycemic control, perinatal outcome and postpuerperal glucose tolerance in impaired glucose tolerance (IGT) pregnant women who failed to achieve desired glycemic control by dietary regime.

METHODS

A total of 280 participants were classified in two groups: Group A patients continued with dietary regime and Group B patients were treated with adjuvant insulin therapy. Glycemic control was assessed by laboratory and ultrasonograph means. Pregnancy outcomes were evaluated by prevalence of pregnancy induced hypertension (PIH), high birth weight, neonatal hypoglycemia and caesarean section rates. Postpuerperal glucose tolerance was assessed by oral glucose tolerance test (oGTT).

RESULTS

All laboratory and ultrasound indicators of glycemic control had significantly lower values in Group B. Group A women were more likely to develop the EPH (Edema, Proteinuria, Hypertension) syndrome, 20% versus 7.86% (p = 0.003). High birth weight occurred more frequently in Group A, but the difference was not significant (p = 0.197). Higher rate of caesarean delivery was in Group A than in Group B, 16.43% versus 26.43% (p = 0.041). The difference in neonatal hypoglycemia was not significant (p = 0.478). Pathological oGTT results were observed in 73 Group A patients and in 15 Group B patients.

CONCLUSION

Lower caesarean section rates and the EPH syndrome incidence are the benefits of adjuvant insulin therapy in IGT patients.

Diagnostic criteria for gestational diabetes mellitus

AIM

To answer two questions: is there a threshold for pathological hyperglycaemia after 24 weeks of gestation? What are the diagnostic criteria for gestational diabetes mellitus?

MATERIALS AND METHODS

Review of the literature considering the relationships between glucose values and complications during pregnancy in women without specific care for this condition. Only the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study meets sufficient quality criteria.

RESULTS

Increasing glucose values during pregnancy, either at fasting and after a 75-g oral glucose tolerance test, are independently associated according to a continuum with an increased risk of maternal-foetal complications, especially birth weight above the 90th percentile for gestational age, Caesarean delivery and foetal hyperinsulinemia. There is no obvious threshold at which risks increase. The International Association of Diabetes Pregnancy Study Group has proposed the following criteria, considering the glycemic values associated with a 1.75-fold increased risk of macrosomia, foetal hyperinsulinemia and adiposity in the HAPO study: fasting plasma glucose ≥ 0.92 g/L (5.1 mmol/L) and/or 1-hour plasma glucose value ≥ 1.80 g/L (10.0 mmol/L) and/or 2-hour plasma glucose value ≥ 1.53 g/L (8.5 mmol/L).

CONCLUSION

The choice of glycemic thresholds for defining gestational diabetes mellitus is necessarily arbitrary because of a continuum (NP2). Only experts may propose definition criteria.

The relationship between pregnancy weight gain and glucose tolerance status among black and white women in central North Carolina

OBJECTIVE

The objective of the study was to examine weight and its relationship to glucose intolerance during pregnancy.

STUDY DESIGN

Women were classified into mutually exclusive glucose tolerance groups; impaired glucose tolerance of pregnancy defined as 1 high value on the oral glucose tolerance test, gestational diabetes mellitus as 2 high values, and normal glucose tolerance as a normal value on the universal screen test. Logistic regression was used to examine the relationship between prepregnancy body mass index and weight gain, and glucose tolerance status and predicted probabilities were calculated.

RESULTS

Weight gain ratio (observed/expected) was significantly higher for women with gestational diabetes mellitus, compared with women with normal glucose tolerance. The likelihood of developing gestational diabetes mellitus was significantly increased by both prepregnancy overweight (odds ratio 2.2, 95% confidence interval 1.1-4.3) and obese status (odds ratio 3.7, 95% confidence interval 2.2-6.3) but only marginally by weight gain ratio. In contrast, the likelihood of developing impaired glucose tolerance was increased by weight gain ratio for women who started pregnancy overweight.

CONCLUSION

Prepregnancy weight was strongly associated with gestational diabetes mellitus, whereas weight gain during pregnancy was associated with impaired glucose tolerance only among overweight women.

Comparison of maternal-fetal outcomes in gestational diabetes and lesser degrees of glucose intolerance+

AIM

To determine the relationships between maternal and fetal outcomes and gestational diabetes mellitus (GDM), impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), respectively.

METHODS

A retrospective cohort study design was used with 149 patients with abnormal oral glucose tolerance test (OGTT) and 149 normal patients. Statistical analysis used was the chi-squared test, Fisher's exact test or the Student's t-test, as appropriate. P < 0.05 was considered significant.

RESULTS

The level of hyperglycemia according to the OGTT (World Health Organization criteria) was associated with pre-eclampsia, polyhydramnios and macrosomia in GDM patients. There was no increase in the complications of preterm labor and premature rupture of membranes, despite the increased risk of polyhydramnios. Although treated with insulin, macrosomia still occurred in patients with GDM, but there was no shoulder dystocia as there was an increase in the incidence of cesarean section (CS). The IGT group was not associated with adverse fetal or maternal outcomes, but there was an increase in intervention and the incidence of CS. The IFG group was associated with a significantly increased risk of pre-eclampsia and macrosomia. These findings challenge the concept of IFG being a lesser pathology than GDM. Further prospective studies with a larger number of patients are needed to ascertain the significance of these findings.

CONCLUSION

There was an increased risk of pre-eclampsia and macrosomia in both the GDM and IFG patients, but IGT was not associated with adverse fetal or maternal outcomes.

Effect of macronutrient intake on the development of glucose intolerance during pregnancy

BACKGROUND

Dietary intake influences glucose tolerance status, yet the relation between macronutrient intake and the development of glucose intolerance during pregnancy has not been adequately examined.

OBJECTIVE

We examined the relation between macronutrient intake early in pregnancy and the development of glucose intolerance.

DESIGN

Data are from 1698 women in the Pregnancy, Infection, and Nutrition Study. Dietary intake during the second trimester was assessed with a food-frequency questionnaire. Women were classified into 1 of 3 glucose categories: gestational diabetes mellitus (GDM), impaired glucose tolerance (IGT), and normal glucose tolerance. Multivariate logistic regression was used to calculate the relative risk of IGT and GDM, with adjustment for potential confounders. A series of models were specified to test alternate hypotheses about the relation of diet to risk of IGT or GDM.

RESULTS

The overall prevalences of IGT and GDM in the cohort were 2.6% and 5.2%, respectively. The addition model showed that adding 100 kcal from carbohydrates to the diet was associated with a 12% decrease in risk of IGT and a 9% decrease in risk of GDM. The substitution model showed that substituting fat for carbohydrates (per each 1% of total calories) resulted in a significant increase in risk of both IGT and GDM [relative risk = 1.1 (95% CI: 1.02, 1.12) and 1.1 (1.02, 1.10), respectively]. Predicted probabilities of IGT and GDM were reduced by one-half with a 10% decrease in dietary fat and a 10% increase in carbohydrate.

CONCLUSIONS

This study found an association between increased fat intake and the development of glucose abnormalities in pregnancy.

Epidemiology of gestational diabetes mellitus and its association with Type 2 diabetes

Gestational diabetes (GDM) is defined as carbohydrate intolerance that begins or is first recognized during pregnancy. Although it is a well-known cause of pregnancy complications, its epidemiology has not been studied systematically. Our aim was to review the recent data on the epidemiology of GDM, and to describe the close relationship of GDM to prediabetic states, in addition to the risk of future deterioration in insulin resistance and development of overt Type 2 diabetes. We found that differences in screening programmes and diagnostic criteria make it difficult to compare frequencies of GDM among various populations. Nevertheless, ethnicity has been proven to be an independent risk factor for GDM, which varies in prevalence in direct proportion to the prevalence of Type 2 diabetes in a given population or ethnic group. There are several identifiable predisposing factors for GDM, and in the absence of risk factors, the incidence of GDM is low. Therefore, some authors suggest that selective screening may be cost-effective. Importantly, women with an early diagnosis of GDM, in the first half of pregnancy, represent a high-risk subgroup, with an increased incidence of obstetric complications, recurrent GDM in subsequent pregnancies, and future development of Type 2 diabetes. Other factors that place women with GDM at increased risk of Type 2 diabetes are obesity and need for insulin for glycaemic control. Furthermore, hypertensive disorders in pregnancy and afterwards may be more prevalent in women with GDM. We conclude that the epidemiological data suggest an association between several high-risk prediabetic states, GDM, and Type 2 diabetes. Insulin resistance is suggested as a pathogenic linkage. It is possible that improving insulin sensitivity with diet, exercise and drugs such as metformin may reduce the risk of diabetes in individuals at high risk, such as women with polycystic ovary syndrome, impaired glucose tolerance, and a history of GDM. Large controlled studies are needed to clarify this issue and to develop appropriate diabetic prevention strategies that address the potentially modifiable risk factors.

False-Positive 1-Hour Glucose Challenge Test and Adverse Perinatal Outcomes

OBJECTIVE

To determine whether a false-positive 1-hour glucose challenge test (GCT) is associated with perinatal complications.

METHODS

We performed a retrospective cohort study of 1825 eligible pregnant women among a cohort of 1998 patients. Patients were screened for gestational diabetes mellitus (GDM) with the 1-hour 50-g GCT at 24-28 gestational weeks. A false-positive GCT was defined as a result greater than or equal to 135 mg/dL followed by a normal 3-hour glucose tolerance test (GTT). We compared the negative GCT and false-positive GCT cohorts for a composite perinatal outcome variable that included fetal macrosomia, antenatal death, shoulder dystocia, chorioamnionitis, preeclampsia, intensive care nursery admission, and postpartum endometritis. Secondary outcomes included cesarean delivery and each component variable of the composite. Unadjusted, stratified, and multiple logistic regression analyses were used to investigate the association between a false-positive GCT and the development of perinatal complications.

RESULTS

We identified 164 patients with a false-positive GCT and 50 patients with GDM. The false-positive GCT cohort on average was older, of higher parity, had a higher body mass index, and more frequently had chronic hypertension, sickle cell trait, and elevated midtrimester human chorionic gonadotropin levels. The false-positive GCT cohort more frequently had adverse perinatal outcomes, including the composite perinatal outcome (odds ratio [OR] 5.96, 95% confidence interval[CI]1.47,24.16), macrosomia greater than 4500 g (OR 3.66, 95% CI 1.30, 10.32), antenatal death (OR 4.61, 95% CI 0.77, 27.48), shoulder dystocia (OR 2.85, 95% CI 1.25, 6.51), endometritis (OR 2.18, 95% CI 1.03, 4.63), and cesarean delivery (OR 1.76, 95% CI 0.99, 3.14).

CONCLUSION

A false-positive GCT is an independent risk factor for adverse perinatal outcomes.

The association between impaired glucose tolerance and birth weight among black and white women in central North Carolina

OBJECTIVE

This study examines the relationship of glucose intolerance during pregnancy to birth weight among black and white participants of the Pregnancy, Infection, and Nutrition Study.

RESEARCH DESIGN AND METHODS

This prospective cohort study recruited women from prenatal clinics in central North Carolina at 24-29 weeks' gestation. A 1-h 50-g glucose challenge test (GCT) and 100-g oral glucose tolerance test (OGTT) were conducted. Impaired glucose tolerance (IGT) was defined as one high value on the OGTT, gestational diabetes mellitus (GDM) as two or more high values, and normal glucose tolerance (NGT) was defined as a low or high value on the GCT screen but no high values on the OGTT. Women with known glucose status and birth outcome information were included in this analysis (n = 2055).

RESULTS

Black women with IGT had higher rates of both macrosomia (38.5%) and large for gestational age (LGA) (53.9%) compared with white women (10.0% and 13.2%). Black infants' birth weights (3800 g) and prevalence of macrosomia and LGA were significantly higher among mothers with IGT compared with NGT women (birth weight, 3184 g; macrosomia, 7.0%; LGA, 11.6%). In contrast, among white infants, there was no significant increase in birth weight, macrosomia, or LGA associated with the mother's glucose tolerance status. In addition, there was no effect of GDM on birth weight in either group.

CONCLUSIONS

This study suggests that, independent of maternal prepregnant weight, there may be significant increased risk of macrosomia among black IGT women but not among white IGT women. Further investigations into factors that may contribute to the observed results are needed.

Women with impaired glucose tolerance during pregnancy have significantly poor pregnancy outcomes

OBJECTIVE

This article tests the hypothesis that women with impaired glucose tolerance (IGT) have the same pregnancy outcomes as those of their counterparts with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

From December 1998 to December 1999, 84 of 90 antenatal care base units (ACBUs) under the Tianjin Antenatal Care Network in China participated in the first screening program for gestational diabetes mellitus (GDM). A total of 9,471 pregnant women under the care of participating ACBUs were screened. Of the women screened, 154 were positive for IGT. Of the 154 women, 102 opted for conventional obstetric care. The comparison group was 302 women of normal glucose tolerance (NGT). The initial screening consisted of a 50-g 1-h glucose test, and was carried out at 26-30 gestational weeks. Women with a serum glucose > or =7.8 mmol/l were followed up with a 75-g 2-h oral glucose tolerance test. The World Health Organization's diagnostic criteria for GDM were used.

RESULTS

Women with IGT were at increased risk for premature rupture of membranes (P-ROM) (odds ratio [OR] 10.07; 95% CI 2.90-34.93); preterm birth (6.42; 1.46-28.34); breech presentation (3.47; 1.11-10.84); and high birth weight (90th percentile or 4,000 g) (2.42; 1.07-5.46); adjusting for maternal age, pregravid BMI, hospital levels, and other confounding factors.

CONCLUSIONS

The presence of IGT in pregnancy is predictive of poor pregnancy outcomes.

HAPO Study Cooperative Research Group. The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study

OBJECTIVE

The objective of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study is to clarify unanswered questions on associations of maternal glycemia, less severe than overt diabetes mellitus, with risks of adverse pregnancy outcome. This report describes the background and design of the HAPO Study.

METHODS

HAPO is a 5-year investigator-initiated prospective observational study that will recruit approximately 25000 pregnant women in 10 countries. HAPO utilizes a Central Laboratory for measurement of key metabolic variables, a Clinical Coordinating Center, a Data Coordinating Center, and an independent Data Monitoring Committee. Glucose tolerance is assessed by a 75 g 2-h OGTT at 24-32 weeks' gestation. Results are unblinded to the woman and her caregivers if: fasting plasma glucose >5.8 mmol/l, 2-h plasma glucose >11.1 mmol/l or any plasma glucose <2.5 mmol/l. Random plasma glucose measurement is performed at 34-37 weeks or if symptoms suggest hyperglycemia; results are unblinded for values > or = 8.9 mmol/l. Sociodemographic and health history data are collected via questionnaire and medical record abstraction. Maternal blood is obtained for measurement of serum C-peptide and hemoglobin A1c (HbA(1C)), cord blood for serum C-peptide and plasma glucose, and a capillary specimen is taken between 1 and 2 h following delivery for neonatal plasma glucose. Neonatal anthropometrics are obtained, and follow-up data are collected at 4-6 weeks post-delivery. The primary outcomes to be assessed in relation to maternal glycemia are cesarean delivery, increased fetal size (macrosomia/LGA/obesity), neonatal morbidity (hypoglycemia), and fetal hyperinsulinism.

Gestational diabetes mellitus in women of single gravidity in Tianjin City, China

OBJECTIVE

The aim of this study was to investigate the prevalence of gestational diabetes mellitus (GDM) and risk factors for the development of GDM in pregnant women in Tianjin, China, where the prevalence of GDM is still unknown.

STUDY DESIGN AND METHODS

A total of 9,471 pregnant women living in the six urban districts of Tianjin, China, took part in the initial screening between December 1998 and December 1999. The screening test consisted of a 50-g 1-h glucose test. Women with a reading > or =7.8 mmol/l at the initial screening were invited to undergo a 75-g 2-h oral glucose tolerance test (OGTT). GDM was confirmed using the World Health Organization's diagnostic criteria.

RESULTS

At the initial screening test, 888 women had a glucose reading of > or =7.8 mmol/l. A total of 701 (79%) women took a subsequent OGTT. Of these, 174 women were confirmed to have GDM (154 with impaired glucose tolerance [IGT] and 20 with diabetes). The prevalence of GDM was 2.31% (2.03% for IGT and 0.28% for diabetes), adjusting for serum glucose levels at the initial screening test. Independent predictors for GDM were maternal age, stature, prepregnancy BMI, weight gain in pregnancy before screening, diabetes in first-degree relatives, and habitual cigarette smoking during pregnancy. Women who smoked or had a short stature are more likely to develop GDM than their counterparts.

CONCLUSIONS

The prevalence of GDM in pregnant women in the city of Tianjin, China, was 2.31%. Short stature and smoking in pregnancy were additional risk factors for GDM.

Gestational diabetes diagnosed in third trimester pregnancy and pregnancy outcome

BACKGROUND

The clinical significance of gestational diabetes diagnosed in the third trimester is unclear. A prospective observational study was performed on a cohort of women without pre-existing gestational diabetes or other medical disorders to examine the effect of gestational diabetes on pregnancy complications and infant outcome.

METHODS

Four hundred and eighty-nine consecutive women were assessed at 28-30 weeks by random glucose screening and/or a 75 g oral glucose tolerance test. The subsequent management was according to established departmental protocols. The outcome of pregnancy was compared among the groups with negative screening, positive screening but normal glucose tolerance, and gestational diabetes which was controlled with diet therapy.

RESULTS

Women with gestational diabetes (n=67 or 13.7%) had significantly increased maternal age, pre-pregnancy weight and body mass index, hemoglobin levels at booking and at 36-38 weeks, and incidences of parity >1, pre-eclampsia, and female infants, while the gestational age was shorter and there was no significant difference in the birthweight outcome or neonatal morbidity.

CONCLUSIONS

Despite diet treatment, gestational diabetes diagnosed in the last trimester is associated with increased risk of pre-eclampsia and shorter length of gestation, and this is likely to reflect a pathological process rather than the physiological effect of pregnancy on maternal glucose tolerance.