Gestational diabetes mellitus. Influence of race on disease prevalence and perinatal outcome in a U.S. population

Prevalence of gestational diabetes in the United States and Canada: a systematic review and meta-analysis

BACKGROUND

An understanding of the prevalence of gestational diabetes mellitus among pregnant women is essential at local, national and international level so that appropriate health care interventions can be planned, financed and delivered.

METHODS

A systematic review and meta-analysis of primary research reporting the prevalence of gestational diabetes mellitus in Canada or the United States were carried out according to Meta-analysis of Observational Studies in Epidemiology guidelines. Four electronic databases were systematically searched in June 2023 to identify articles that reported gestational diabetes mellitus prevalence using universal screening in pregnant women from eligible general population samples. Estimates were combined using a random effects model, and the effects of moderator variables analysed.

RESULTS

There were 36 separate samples of women or deliveries (total sample size 1,550,917). Overall mean prevalence of gestational diabetes mellitus was 6.9% (95% CI: 5.7-8.3); 13.7% (95% CI: 10.7-17.3) in studies using a one-step screening strategy, and 5.2% (95% CI: 4.4-6.1) in those using a two-step strategy. Heterogeneity in technical methods between studies produced differences in estimates, as did different diagnostic thresholds used.

CONCLUSIONS

The meta-analysis suggests a slightly higher prevalence of gestational diabetes mellitus in Canada and the United States, compared to Europe, but highlights the need for standardised protocols for estimating gestational diabetes mellitus prevalence.

Risk of obstetric and neonatal morbidity in gestational diabetes in a single institution: A retrospective, observational study

Gestational diabetes mellitus (GDM) is defined as a carbohydrate intolerance with onset or first recognition occurring during pregnancy and GDM could be risk factor for various maternal fetal complications. This study aimed to investigate risks of maternal and neonatal outcomes according to GDM and normal glucose tolerance. This retrospective, observational study included singleton pregnant women who had received a 50-g oral glucose challenge test in 2nd trimester of gestation and gave birth at National Health Insurance Service Ilsan Hospital. Maternal and neonatal complications were compared between GDM and non-GDM groups. Among the 682 women, 56 were diagnosed with GDM and 626 were non-GDM group. Maternal age was older and prepregnant body mass index was higher in GDM. The rate of cesarean delivery, preeclampsia, and transfusion was similar; however, the incidence of preterm birth was higher in GDM. Multivariate analysis, however, showed that GDM was independent risk factor only for preterm birth in <37 weeks (adjusted odds ratio, 2.25; 95% confidence interval, 1.16-4.36). Regarding neonatal morbidities, APGAR score <7 at 5 minutes and the rate of macrosomia were similar; however, the rates of neonatal intensive care unit (NICU) admission, large for gestational age (LGA), and intubation were higher in GDM. Multivariate analysis, however, showed that GDM was not independent risk factor for LGA, NICU admission, and intubation rate. Compared with the non-GDM group, GDM was associated with an increased likelihood of preterm birth <37 weeks, however, did not increase cesarean delivery, postpartum hemorrhage, LGA, and NICU admission rate. This study showed that the majority of women with GDM delivered with similar maternal and neonatal outcomes in non-GDM women.

Influence of Pre-Pregnancy Underweight Body Mass Index on Fetal Abdominal Circumference, Estimated Weight, and Pregnancy Outcomes in Gestational Diabetes Mellitus

This study aimed to determine the influence of pre-pregnancy body mass index on pregnancy outcomes in gestational diabetes mellitus (GDM), comparing underweight patients with GDM with normal weight patients with GDM. Maternal baseline characteristics, ultrasonographic results, and pregnancy and neonatal outcomes were reviewed in 946 women with GDM with singleton pregnancies. Underweight patients with GDM showed a benign course in most aspects during pregnancy, except for developing a higher risk of giving birth to small for gestational age neonates. Underweight women with GDM required less insulin treatment, had a higher rate of vaginal delivery, and had a lower rate of cesarean delivery. In addition, their neonates were more likely to have fetal abdominal circumference and estimated fetal weight below the 10th percentile both at the time of GDM diagnosis and before delivery. Notably, their risk for preeclampsia and macrosomia were lower. Collectively, our data suggest that underweight women with GDM may require a different approach in terms of diagnosis and management throughout their pregnancy.

Racial and ethnic disparities in chronic health conditions among women with a history of gestational diabetes mellitus

Background: This study aims to examine and determine the role of race/ethnicity in chronic conditions in women diagnosed with gestational diabetes mellitus (GDM) during any of their previous pregnancies. Methods: We used the National Health and Nutrition Examination Survey (NHANES) from2007-2016 to identify women who self-reported prior GDM and chronic disease diagnoses such as cardiovascular disease, hypertension, depression, and type 2 diabetes mellitus (T2DM).We used bivariate analysis using the chi-square test (χ²) and multiple logistic regressions to perform statistical test for associations, taking into consideration design and sample weight. Results: Among participants with prior GDM diagnoses, black women had a 74.4% prevalence of chronic disease, followed by Whites, 58.5% Hispanics, 58.0%, and Asians, 51.9% (P=0.009).Black women with prior GDM diagnoses had 2.4 odds of having chronic conditions compared to Whites (adjusted odds ratio [AOR]=2.40, 95% confidence interval [CI] = 1.28-4.50). In addition, they had higher odds of being former smokers (AOR=1.73, 95% CI=1.01-2.96),current smokers (AOR=1.96, 95% CI=1.06-3.61), having a body mass index (BMI) of 25-29.9(AOR=2.55, 95% CI=1.10-5.87), or a BMI ≥30 (AOR=4.09, 95% CI = 2.05-8.17) compared to their White counterparts. Hispanic women had lower odds of being diagnosed with GDM and associated chronic diseases. Conclusion: Black women with GDM were disproportionally affected and at higher risk to be diagnosed with chronic conditions. Smoking and obesity were strongly associated with chronic disease diagnoses. Our findings also suggest a 'Hispanic Paradox', requiring further study. These findings inform primary care clinicians and Obstetricians, and Gynecologists of at-risk patients who could benefit from lifestyle modification recommendations and counseling.

Comparison of criteria of International Association of Diabetes and Pregnancy Study Groups (IADPSG) with National Institute for Health and Care Excellence (NICE) for diagnosis of gestational diabetes mellitus

BACKGROUND

Different screening procedures and diagnostic criteria are being followed in the same as well as in different countries with no single standard criteria established for diagnosis of GDM. So far, there are no studies in the Indian population comparing IADPSG with NICE criteria.

OBJECTIVE

To compare International Association of Pregnancy and Study Groups (IADPSG) criteria with the National Institute for Health and Care Excellence (NICE) for diagnosis of gestational diabetes mellitus and its influence on maternal and perinatal outcomes.

METHOD

This prospective observational study was conducted in the Department of Obstetrics and Gynaecology of a tertiary care institute in South India from March 2017 to October 2018. Six-hundred and eighty women with or without risk factors for GDM were recruited in the study and screened for GDM based on IADPSG and NICE criteria. Women with preexisting diabetes mellitus or with fasting plasma glucose ≥ 126 mg/dl were excluded.

RESULTS

The overall prevalence of GDM in our study was 27.2% by either IADPSG/NICE criteria. In this study, 25.1% women and 11.6% women were diagnosed as GDM using IADPSG and NICE criteria, respectively. The level of agreement between the two diagnostic criteria was found to be poor in our study and was statistically significant (kappa = 0.429, p < 0.001). Women testing IADPSG-positive NICE-negative had a higher risk of GHTN, abortions, PROM, preterm delivery, caesarean section and congenital anomalies, meconium-stained liquor, and low Apgar scores at 1 min when compared to non GDM group. In addition, except for preterm delivery, women diagnosed as GDM by both IADPSG and NICE criteria had adverse outcomes such as preeclampsia, urinary tract infection, and polyhydramnios. Women diagnosed as GDM in IADPSG-negative NICE-positive had no significant adverse maternal or perinatal outcomes.

CONCLUSIONS

IADPSG criteria appear to be more robust than NICE criteria for diagnosis of GDM. Women with substantial risk of maternal and perinatal outcomes are better identified by IADPSG criteria who would have been missed if NICE criteria was used.

Relationship Between Pregnancy Complications and Subsequent Coronary Artery Disease Assessed by Coronary Computed Tomographic Angiography in Black Women

BACKGROUND

Maternal pregnancy complications, particularly preeclampsia and gestational diabetes mellitus, are described to increase the risk for subsequent coronary artery disease (CAD). In addition, black women are at higher risk for CAD. The objective of this study was to compare the prevalence and extent of CAD as detected by coronary computed tomographic angiography (CCTA) in black women with and without a history of prior pregnancy complications.

METHODS

We retrospectively evaluated patient characteristics and CCTA findings in groups of black women with a prior history of preterm delivery (n=154), preeclampsia (n=137), or gestational diabetes mellitus (n=148), and a matched control group of black women who gave birth without such complications (n=445). Univariate and multivariate analyses were performed to assess risk factors of CAD.

RESULTS

All groups with prior pregnancy complications showed higher rates of any (≥20% luminal narrowing) and obstructive (≥50% luminal narrowing) CAD (preterm delivery: 29.2% and 9.1%; preeclampsia: 29.2% and 7.3%; and gestational diabetes mellitus: 47.3% and 15.5%) compared with control women (23.8% and 5.4%). After accounting for confounding factors at multivariate analysis, gestational diabetes mellitus remained a strong risk factor of any (odds ratio, 3.26; 95% CI, 2.03-5.22; P<0.001) and obstructive CAD (odds ratio, 3.00; 95% CI, 1.55-5.80; P<0.001) on CCTA.

CONCLUSIONS

Black women with a history of pregnancy complications, particularly gestational diabetes mellitus, have a higher prevalence of CAD on CCTA while only a history of gestational diabetes mellitus was independently associated with any and obstructive CAD on CCTA.

Screening for gestational diabetes mellitus: a Caribbean perspective

Gestational diabetes mellitus (GDM) is defined as a glucose intolerance first recognised in pregnancy. The World Health Organization (WHO) in 2015 revised the definition into either diabetes in pregnancy (DIP) which includes pre-existing diabetes (type 1 or type 2) that antedates pregnancy or diabetes diagnosed during pregnancy with the WHO diagnostic criteria for diabetes mellitus (DM) in the non-pregnant state, and GDM for milder forms of hyperglycaemia in pregnancy. The main purpose of the screening and diagnosis of GDM is to identify pregnancies in which the foetus is at a high risk of an adverse perinatal outcome, and the mother and the offspring are of serious long-term sequelae. This review of the literature provides an overview of associated prevalence, risk factors and diagnosis of GDM. It also addresses the benefits of screening with supportive evidence. Based on this review, we recommend especially in low-resourced countries such as the Caribbean, adoption of a universal screening with the two-step method.

PECULIARITIES OF THE COURSE OF GESTATION AND PREGNANCY OUTCOMES IN WOMEN WITH GESTATIONAL DIABETES MELLITUS

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with high frequency of obstetric complications, such as gestosis, polyhydramnios, urogenital infection, premature birth. An increase in the number of cases of detection of GDM in pregnant women living in Kazakhstan is noted recently.

OBJECTIVE

This research was carried out in order to see the influence of GDM on the course of the third trimester of pregnancy, outcomes and fetal status in women of Kazakh ethnic group.

RESEARCH DESIGN

Cohort observational study.

SUBJECTS AND METHODS

The main group of research consisted of 61 pregnant women with GDM (Meanage= 32.8±6.314), the control group included 39 pregnant women with normal glucose tolerance (Meanage=30±5.432 years). The pregnant women in both groups were examined by calculation of body mass index (BMI), determination of fasting plasma glucose and the system of hemostasis. Also, the fetal ultrasound was implemented and the uterine-placental, fetal-placental blood flow were evaluated using the Doppler mode.

RESULTS

In the main group initial BMI was equal to Mean=31.1±7.433 kg/m2; we revealed manifestation of gestational hypertension in 36.1%, 95%CI (2.52, 48.6); preeclampsia was diagnosed in 14.8% (95%CI (8; 25.7); the disorders of uteroplacental and fetoplacental blood flow recorded significantly more frequently in main group RR=6.393, 95%CI (1.581-25.840), like the diabetic fetopathy RR=5.115, 95%CI (1.240-21.033). The premature delivery, the prevalence of induction of delivery and intranatal trauma were significantly more frequent in women with GDM.

CONCLUSIONS

GDM significantly worsens course of gestation.

Emergency Room Utilization After Medically Complicated Pregnancies: A Medicaid Claims Analysis

BACKGROUND

Women with pregnancy complications benefit from closer monitoring postpartum and beyond. Increased postpartum emergency room (ER) use may indicate unmet need for outpatient obstetrics and primary care. The purpose of this study was to evaluate whether women with pregnancy complications (gestational diabetes [GDM], gestational hypertension, and preeclampsia) have increased ER use in the first 6 months postpartum, compared with women without these complications.

METHODS

We conducted a retrospective population-based cohort study using a 2003-2010 Maryland Medicaid managed care claims data set, linked with U.S. Census data. Data included claims for outpatient and ER visits for women aged 12-45 years who were continuously enrolled in Medicaid for at least 100 days of pregnancy and 90 days postpartum. We used logistic regression to calculate the association between pregnancy complications and having ≥1 ER visit in the 6 months postpartum.

RESULTS

We identified 26,074 pregnancies, of which 20% were complicated by GDM, gestational hypertension, or preeclampsia. Of these complicated pregnancies, 42.1% had GDM, 35.4% had gestational hypertension, and 42.5% had preeclampsia (diagnoses were not mutually exclusive). In the 6 months postpartum, 25% of women had ≥1 ER visits. Of the complicated pregnancy group, 27.7% had ≥1 ER visit, versus 23.6% of the comparison group (p<0.0001). In adjusted analyses, women with a pregnancy complication were more likely to have ≥1 ER visit compared with women without these complications (odds ratio [OR]1.14, 95% confidence interval [CI] 1.05-1.23). The strength of association was highest in women under age 25 (OR 1.20, 95% CI 1.09-1.33). Preconception medical comorbidities (type 2 diabetes, chronic hypertension, obesity, asthma, mental health, and substance abuse diagnoses) were also strongly associated with postpartum ER use (OR 1.61, 95% CI 1.51-1.73).

CONCLUSIONS

Pregnancy complications increased ER utilization during the 6 months postpartum, especially among women under age 25 years. Interventions that improve discharge planning and early postpartum care may decrease ER use.

Racial/Ethnic Differences in Insulin Resistance and Beta Cell Function: Relationship to Racial Disparities in Type 2 Diabetes among African Americans versus Caucasians

Both biological and sociocultural factors have been implicated in the well-documented racial disparity in incidence and prevalence of type 2 diabetes (T2D) between African Americans (AA) and non-Hispanic whites (NHW). This review examines the extent to which biological differences in glucose metabolism, specifically insulin resistance and beta cell function (BCF), contribute to this disparity. The majority of available data suggests that AA are more insulin resistant and have upregulated BCF compared to NHW. Increasing evidence implicates high insulin secretion as a cause rather than consequence of T2D; therefore, upregulated BCF in AA may specifically confer increased risk of T2D in this cohort. Racial disparities in the metabolic characteristics of T2D have direct implications for the treatment and health consequences of this disease; therefore, future research is needed to determine whether strategies to reduce insulin secretion in AA may prevent or delay T2D and lessen racial health disparities.

The effect of impaired 50-gram oral glucose challenge test on fetal abdominal wall thickness

BACKGROUND

Patients with impaired 50-g oral glucose challenge test (OGCT) have not been investigated for fetal anterior abdominal wall thickness until now. We aimed to investigate patients with impaired 50-g OGCT, but not gestational diabetes and match them with healthy uneventful pregnant participants for anterior abdominal wall thickness, estimated fetal weight, fetal gender, biparietal diameter, femur length and abdominal circumference.

METHODS

A total of 99 pregnant women between 26 and 28 weeks of gestation were enrolled in the study. These patients were divided into two groups according to their 50-g OGCT results. Fifty-one pregnant women with uncomplicated healthy singleton pregnancies constituted our control group, and 48 singleton pregnant women with impaired 50-g OGCT but normal 100-g oral glucose tolerance test constituted our study group.

RESULTS

We detected statistically significant high body mass index in impaired 50-g glucose test group. Biparietal diameter, femur length, abdominal circumference and estimated fetal weight values were not significantly different between groups; however, anterior abdominal wall thickness value was significantly width in impaired 50-g glucose test group. Moreover, there were no statistically significant differences between two groups for gender of fetuses.

CONCLUSION

Impaired 50-g glucose test in pregnancy is related not only to increased maternal body mass index but also to fetal fat distribution. Although fetal abdominal circumference measurement and estimated fetal weight were not different between study and control group, increased anterior abdominal wall thickness can be detected in impaired 50-g OGCT group.

Diabetes in low-resourced countries

Maternal and newborn health poses one of the greatest health challenges in the developing world. Many low-income countries are now experiencing a demographic and epidemiological transition and changing of lifestyles. Thus, apparent "Western" diseases such as diabetes and obesity have been reaching the Third World countries. There is a paucity of reliable data on diabetes in pregnancy in many low-income countries. Adequate information about maternal and perinatal mortality and morbidity as a consequence of diabetes in pregnancy is scarce. This chapter presents evidence of the magnitude and impact of diabetes in pregnancy. Additionally, we discuss interventions in screening and managing diabetes in pregnancy in these specific patient populations.

A comparison of fasting plasma glucose and glucose challenge test for screening of gestational diabetes mellitus

Glucose challenge test (GCT) has been used as an effective screening test for gestational diabetes mellitus (GDM), though it has its own limitations. Hence, we assessed the effectiveness of fasting plasma glucose (FPG) as a simpler alternative procedure. A prospective study was done in 500 pregnant women with gestational age between 22 and 37 weeks. FPG, GCT and GTT were performed in all patients using the glucose oxidase/peroxidase method. The overall sensitivity and specificity of GCT were 75.0% and 92.0%, respectively and the corresponding values for FPG were 88.8% and 95.2%. The positive predictive value and negative predictive value were 42.2% and 97.9% for GCT and 59.2% and 99.1% for FPG, respectively. We conclude that FPG can be used as an effective screening tool for gestational diabetes mellitus.

Advancements and challenges in generating accurate animal models of gestational diabetes mellitus

The maintenance of glucose homeostasis during pregnancy is critical to the health and well-being of both the mother and the developing fetus. Strikingly, approximately 7% of human pregnancies are characterized by insufficient insulin production or signaling, resulting in gestational diabetes mellitus (GDM). In addition to the acute health concerns of hyperglycemia, women diagnosed with GDM during pregnancy have an increased incidence of complications during pregnancy as well as an increased risk of developing type 2 diabetes (T2D) later in life. Furthermore, children born to mothers diagnosed with GDM have increased incidence of perinatal complications, including hypoglycemia, respiratory distress syndrome, and macrosomia, as well as an increased risk of being obese or developing T2D as adults. No single environmental or genetic factor is solely responsible for the disease; instead, a variety of risk factors, including weight, ethnicity, genetics, and family history, contribute to the likelihood of developing GDM, making the generation of animal models that fully recapitulate the disease difficult. Here, we discuss and critique the various animal models that have been generated to better understand the etiology of diabetes during pregnancy and its physiological impacts on both the mother and the fetus. Strategies utilized are diverse in nature and include the use of surgical manipulation, pharmacological treatment, nutritional manipulation, and genetic approaches in a variety of animal models. Continued development of animal models of GDM is essential for understanding the consequences of this disease as well as providing insights into potential treatments and preventative measures.

Gestational diabetes, pre-pregnancy obesity and pregnancy weight gain in relation to excess fetal growth: variations by race/ethnicity

AIMS/HYPOTHESIS

The escalating rate of childhood obesity is a public health concern worldwide, with children in certain ethnic groups being disproportionately affected. Our objective was to examine the joint effects of pre-pregnancy adiposity, pregnancy weight gain and gestational diabetes (GDM) in relation to excess fetal growth and to identify susceptible races or ethnic populations.

METHODS

The risk for delivery of a large-for-gestational-age (LGA) infant, specific to race and fetal sex, was evaluated in 105,985 pregnancies in the Consortium on Safe Labor from 2002-2008. Generalised estimating equations were used to estimate the risk for delivery of LGA infants. Joint effects were employed to evaluate the interplay of three risk factors. Models were stratified by racial group considering one, two or three factors (i.e. pre-pregnancy adiposity, pregnancy weight gain and GDM, with 0 factors as the reference group).

RESULTS

Greater pre-pregnancy adiposity, pregnancy weight gain and GDM were independently associated with increased risk of giving birth to an LGA infant across all races (except GDM among non-Hispanic whites), in both underweight and normal-weight women. Among non-Hispanic white, non-Hispanic black and Hispanic women, the three-factor joint effect was associated with substantially increased odds of LGA (OR [95% CI] 11.27 [8.40, 15.11], 7.09 [4.81, 10.45] and 10.19 [6.84, 15.19], respectively). However, for Asian women the joint effect of all three factors (OR [95% CI] 5.14 [2.11, 12.50]) was approximately the same as any of the two factors.

CONCLUSIONS/INTERPRETATION

GDM, pre-pregnancy obesity and excessive pregnancy weight gain were jointly associated with elevated risk of giving birth to an LGA infant and the effects varied by race. This suggests that those involved in public health efforts aimed at preventing LGA deliveries should consider variations in racial groups when devising effective strategies.

Maternal racial origin and adverse pregnancy outcome: a cohort study

OBJECTIVE

To examine the association between maternal racial origin and a wide range of adverse pregnancy outcomes after adjustment for confounding factors in obstetric history and maternal characteristics.

METHODS

This was a retrospective study in women with singleton pregnancies attending their first routine hospital visit at 11 + 0 to 13 + 6 weeks of gestation. Data on maternal characteristics, and medical and obstetric history were collected and pregnancy outcomes ascertained. Regression analysis was performed to examine the association between racial origin and adverse pregnancy outcomes including pre-eclampsia (PE), gestational hypertension (GH), gestational diabetes mellitus (GDM), preterm delivery (PTD), small-for-gestational age (SGA), large-for-gestational age (LGA), miscarriage, stillbirth and elective and emergency Cesarean section (CS).

RESULTS

The study population included 76 158 singleton pregnancies with a live fetus at 11 + 0 to 13 + 6 weeks. In addition to maternal characteristics and obstetric history, Afro-Caribbean racial origin was associated with increased risk for miscarriage, stillbirth, PE, GH, spontaneous PTD, GDM, SGA and CS. In women of South Asian racial origin there was increased risk for PE, GDM, SGA and CS, and East Asian race contributed to the prediction of GDM and SGA.

CONCLUSION

Maternal racial origin should be combined with other maternal characteristics and obstetric history when calculating an individualized adjusted risk for adverse pregnancy outcome.

Birth injury in a subsequent vaginal delivery among women with a history of shoulder dystocia

AIM

To examine risk factors for birth injury in a subsequent vaginal delivery among women with a prior delivery complicated by shoulder dystocia.

METHODS

Population-based retrospective cohort study, Washington State (1987-2007). Logistic regression was used to assess risk factors associated with subsequent birth injury.

RESULTS

Of 9232 women who met inclusion criteria, 223 (2.4%) had a subsequent vaginal delivery with birth injury. Birth injury in an index delivery, adjusted odds ratio (aOR) 2.6 [95% confidence interval (CI) 1.7-4.1] and factors in subsequent delivery: birth weight ≥4000 g, aOR 4.4 (95% CI: 3.0-6.3), gestational diabetes, aOR 1.9 (95% CI: 1.2-3.2), Hispanic ethnicity aOR 1.9 (95% CI: 1.2-2.9), and maternal obesity, aOR 1.8 (95% CI: 1.3-2.6) were associated with birth injury.

CONCLUSION

Among women with prior delivery complicated by shoulder dystocia, the risk factors identified in this study should be carefully considered prior to deciding upon route of delivery - cesarean vs. vaginal delivery.

Disparities in the risk of gestational diabetes by race-ethnicity and country of birth

Little information exists on the association between maternal country of birth and risk of gestational diabetes (GDM). We examined within each race-ethnicity group whether the risk of GDM differs between women born inside and outside the US. The study was a cohort study of 216 089 women who delivered an infant between 1995 and 2004 with plasma glucose data from the screening 50-g glucose challenge test and the diagnostic 100-g, 3-h oral glucose tolerance test. The age-adjusted prevalence of GDM varied by race-ethnicity and was lowest for non-Hispanic white (4.1%) and highest among Asian Indians (11.1%). In multivariable models, being born outside of the US was associated with an increased risk of GDM among black, Asian Indian, Filipina, Pacific Islanders, Chinese, Mexicans and non-Hispanic white women, whereas, Japanese and Korean foreign-born women had a decreased risk of GDM. Clinicians should be aware that among certain race-ethnicity groups women born outside the US may be at increased risk of GDM and may warrant special preventive and culturally sensitive care.

Establishing diagnosis of gestational diabetes mellitus: Impact of the hyperglycemia and adverse pregnancy outcome study

The diagnosis of gestational diabetes mellitus (GDM) remains controversial, without universal acceptance of a particular set of diagnostic criteria, and, in fact, a lack of consensus as to whether this is an entity worth diagnosis. Some of the debate derives from differences of opinion about what degree of glucose intolerance should be labeled as GDM. Therefore, it is to be expected that there are different viewpoints on how to detect and screen for GDM. It is believed that early diagnosis will result in a significant improvement in perinatal outcome in these patients. In this review, we discuss the current data concerning screening for GDM and new strategies for GDM diagnosis in light of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study.

Gestational diabetes: diagnosis and management

PURPOSE

To review the diagnosis and management of gestational diabetes.

EPIDEMIOLOGY

In the United States, approximately 2 to 5% of all pregnant women have gestational diabetes. Those women with a family history of type 2 diabetes mellitus, Asian or native American race, Latina ethnicity or obesity are at higher risk for developing gestational diabetes.

CONCLUSION

Women with gestational diabetes who are treated appropriately can achieve good outcomes in the majority of pregnancies. Frequent blood glucose monitoring, nutrition counseling and frequent physician contact allow for individualized care to achieve optimal outcomes. Such treatment includes diet, exercise and insulin. The use of oral hypoglycemic agents is controversial and there is some concern about worse maternal and neonatal outcomes as compared to treatment with insulin. Evolving technologies promise to provide more therapeutic options.

Does physical activity during pregnancy reduce the risk of gestational diabetes among previously inactive women?

BACKGROUND

Gestational diabetes affects approximately 7 percent of all pregnancies in the United States; its prevalence may have increased among all ethnic groups since the early 1990 s. Our study examined whether physical activity during pregnancy reduced the risk of gestational diabetes among women who were physically inactive before pregnancy.

METHODS

We used data from the 1988 National Maternal and Infant Health Survey (NMIHS), a nationally representative sample of mothers with live births. The NMIHS obtained mothers' gestational diabetes diagnoses from care providers and mothers reported their physical activity before and during pregnancy, including the number of months with physical activity and types of physical activity. We developed a physical activity index, the product of the number of months with physical activity, and average metabolic equivalents for specific activities. The analysis included 4,813 women who reported being physically inactive before pregnancy, with singleton births and no previous diabetes diagnosis.

RESULTS

Gestational diabetes was diagnosed in 3.5 percent of the weighted sample in 1988. About 11.8 percent of these previously inactive women began physical activity during pregnancy. Women who became physically active had 57 percent lower adjusted odds of developing gestational diabetes than those who remained inactive (OR 0.43, 95% CI 0.20-0.93). Women who had done brisk walking during pregnancy had a lower adjusted risk of gestational diabetes (OR 0.44, CI 0.19-1.02) and women with a physical activity index score above the median had 62 percent lower odds of developing gestational diabetes than the inactive women (CI 0.15-0.96).

CONCLUSIONS

Results suggest that physical activity during pregnancy is associated with lower risk for gestational diabetes among previously inactive women.

Risk assessment does not explain high prevalence of gestational diabetes mellitus in a large group of Sardinian women

BACKGROUND

A very high prevalence (22.3%) of gestational diabetes mellitus (GDM) was recently reported following our study on a large group of Sardinian women. In order to explain such a high prevalence we sought to characterise our obstetric population through the analysis of risk factors and their association with the development of GDM.

METHODS

The prevalence of risk factors and their association with the development of GDM were evaluated in 1103 pregnancies (247 GDM and 856 control women). The association of risk factors with GDM was calculated according to logistic regression. Sensitivity and specificity of risk assessment strategy were also calculated.

RESULTS

None of the risk factors evaluated showed an elevated frequency in our population. The high risk patients were 231 (20.9%). Factors with a stronger association with GDM development were obesity (OR 3.7, 95% CI 2.08-6.8), prior GDM (OR 3.1, 95% CI 1.69-5.69), and family history of Type 2 diabetes (OR 2.6, 95% CI 1.81-3.86). Only patients over 35 years of age were more represented in the GDM group (38.2% vs 22.6% in the non-GDM cases, P < 0.001). Type 2 diabetes in second-degree relatives was equally represented in GDM and non-GDM subjects, while prior poor obstetrical outcomes mostly characterized non-GDM women (17.5% vs 10.6%, P < 0.001). The "average risk" assessment better characterized non-GDM patients (76.8% vs 57.8%, P < 0.001). The logistic regression analysis confirmed that Type 2 diabetes in second-degree relatives, prior poor obstetrical outcomes and the "average risk" definition did not predict the development of GDM.

CONCLUSION

Such a high prevalence of GDM in our population does not seem to be related to the abnormal presence of some known risk factors, and appears in contrast with the prevalence of Type 2 diabetes in Sardinia. Further studies are needed to explain the cause such a high prevalence of GDM in Sardinia. The "average risk" definition is not adequate to predict GDM in our population.

Periodontal pathogens and gestational diabetes mellitus

In previous cross-sectional or case-control studies, clinical periodontal disease has been associated with gestational diabetes mellitus. To test the hypothesis that, in comparison with women who do not develop gestational diabetes mellitus, those who do develop it will have had a greater exposure to clinical and other periodontal parameters, we measured clinical, bacteriological (in plaque and cervico-vaginal samples), immunological, and inflammatory mediator parameters 7 weeks before the diagnosis of gestational diabetes mellitus in 265 predominantly Hispanic (83%) women in New York. Twenty-two cases of gestational diabetes mellitus emerged from the cohort (8.3%). When the cases were compared with healthy control individuals, higher pre-pregnancy body mass index (p=0.004), vaginal levels of Tannerella forsythia (p=0.01), serum C-reactive protein (p=0.01), and prior gestational diabetes mellitus (p=0.006) emerged as risk factors, even though the clinical periodontal disease failed to reach statistical significance (50% in those with gestational diabetes mellitus vs. 37.3% in the healthy group; p=0.38).

Gestational diabetes as a risk factor for pancreatic cancer: a prospective cohort study

BACKGROUND

Diabetes is known to be associated with cancer of the pancreas, though there is some debate as to whether it is a cause or a consequence of the disease. We investigated the incidence of pancreatic cancer in a cohort of 37926 Israeli women followed for 28-40 years for whom information on diabetes had been collected at the time they gave birth, in 1964-1976, in Jerusalem. There were 54 cases of pancreatic cancer ascertained from the Israel Cancer Registry during follow-up.

METHODS

We used Cox proportional hazards models to adjust for age at baseline and explore effects of other risk factors, including ethnic groups, preeclampsia, birth order and birth weight of offspring.

RESULTS

We observed no cases of pancreatic cancer in the women with insulin dependent diabetes; however, there were five cases in the women with gestational diabetes. The interval between the record of diabetes in pregnancy and the diagnosis of pancreatic cancer ranged from 14-35 years. Women with a history of gestational diabetes showed a relative risk of pancreatic cancer of 7.1 (95% confidence interval, 2.8-18.0).

CONCLUSION

We conclude that gestational diabetes is strongly related to the risk of cancer of the pancreas in women in this population, and that gestational diabetes can precede cancer diagnosis by many years.

Does raising the glucose challenge test threshold impact birthweight in Asian gravidas?

OBJECTIVE

Some authors suggest a glucose challenge test (GCT) threshold of 150 mg/dL in Asian gravidas. The impact of such a policy on outcomes is unknown.

STUDY DESIGN

A retrospective cohort of 1705 Asian gravidas. Subjects (n=95) had a GCT of 140-150 mg/dL and underwent a 3-h glucose tolerance test (GTT). Matched controls (n=190) had a GCT of <140 mg/dL. Birthweight was the primary outcome and the secondary outcomes were cesarean delivery (CD) rate and macrosomia.

RESULTS

Eight subjects (11.9%) had gestational diabetes mellitus (GDM); none had GTT fasting values of >90 mg/dL. Mean birthweight was 3282 g in the subjects and 3238 g in the controls (P=0.39). There were no significant differences in the secondary outcomes.

CONCLUSION

Compared with controls, study patients did not deliver significantly larger infants. However, raising the GCT threshold would have missed 8 subjects (11.9%) with GDM. Raising the GCT threshold to 150 mg/dL in Asian gravidas may unacceptably lower the sensitivity of the screening test.

Gestational diabetes and the risk of breast cancer among women in the Jerusalem Perinatal Study

Gestational diabetes is becoming increasingly common; it is important to determine how it relates to future risk of disease. We investigated the relation of gestational diabetes to breast cancer in 37,926 women who had one or more live births in 1964-1976 for whom information had been collected on complications of pregnancy. In this cohort there were 1,626 cases of breast cancer reported to the Israel Cancer Registry before January 1, 2005 and 410 cases of gestational diabetes recorded from birth records. There were 29 cases of breast cancer among women diagnosed with gestational diabetes. Using Cox proportional hazards models to control for age and birth order at the first observed birth and other characteristics, we found that the incidence of breast cancer was increased among women diagnosed with gestational diabetes (relative rate = 1.5, 95% confidence interval 1.0-2.1). This effect was seen only among women 50 years and older (relative rate 1.7, 95% confidence interval 1.1-2.5) but not among women <50 (relative rate = 1.0, 95% confidence interval 0.5-2.1). The findings suggest that gestational diabetes may be an important early marker of breast cancer risk among post-menopausal women, but these results need to be confirmed in future studies.

Prevalence of gestational diabetes mellitus and the effect of weight on measures of insulin secretion and insulin resistance in third-trimester pregnant rural women residing in the Central Region of Limpopo Province, South Africa

AIMS

To examine the prevalence of gestational diabetes in third-trimester pregnant women as well as to assess their insulin secretion and insulin resistance (IR).

METHODS

Third-trimester pregnant women (n= 262) attending antenatal care at local clinics in the central region of the Limpopo Province underwent a 2-h oral glucose tolerance test (OGTT) with blood collected at 0, 30 and 120 min. Glucose and insulin were measured.

RESULTS

The prevalence of gestational impaired glucose tolerance (GIGT) and gestational diabetes mellitus (GDM) was 8.8% (7.3% GIGT; 1.5% GDM). Women with GIGT/GDM were significantly older and had more children compared with women with a normal response to the OGTT. Homeostasis model assessment(HOMA)-IR and fasting insulin were lower in the GIGT/GDM group compared with the normal group, as were measures of insulin secretion (HOMA B-cell function and insulinogenic index). Furthermore, women with body mass index (BMI)> or =30.0 kg/m2 were significantly older and had higher parity, systolic and diastolic blood pressure measurements than those with BMI 25.0-29.9 kg/m2 and BMI < 25.0 kg/m2. However,increased BMI was not associated with an increased risk of GIGT/GDM.

CONCLUSION

The present study shows that there is a high prevalence of GIGT/GDM, with most women having IGT. The GIGT/GDM present in these women is characterized by increased insulin sensitivity accompanied by reduced pancreatic B-cell function. Additionally, heavier women appear to have increased first phase insulin secretion, suggesting the presence of insulin resistance.

Ethnic differences in perinatal outcome of gestational diabetes mellitus

OBJECTIVE

Despite the high rates of gestational diabetes mellitus (GDM) among certain Pacific Islander and Asian ethnic groups in the U.S., little is known about the risk for adverse perinatal outcomes in these populations. We sought to examine ethnic differences in perinatal outcome among Asian and Pacific-Islander women with GDM.

RESEARCH DESIGN AND METHODS

A retrospective review of all women referred to the largest outpatient GDM program in the state of Hawai'i from 1995 to 2005 was conducted. Patients of Native-Hawaiian/Pacific-Islander, Japanese, Chinese, Filipino, and Caucasian ethnicity were included (n = 2,155). Treatment of all patients consisted of an outpatient education class, dietary management, self-monitoring of blood glucose, and insulin instruction (if indicated). Demographics, maternal and neonatal characteristics, and delivery information were evaluated.

RESULTS

Neonates born to Native-Hawaiian/Pacific-Islander mothers and Filipino mothers had 4 and 2 times the prevalence of macrosomia, respectively, compared with neonates born to Japanese, Chinese, and Caucasian mothers. These differences persisted after adjustment for other statistically significant maternal and fetal characteristics. Ethnic differences were not observed for other neonatal or maternal complications associated with GDM, with the exception of neonatal hypoglycemia and hyperbilirubinemia.

CONCLUSIONS

Significant ethnic differences in perinatal outcomes exist across Asian and Pacific-Islander women with GDM. This finding emphasizes the need to better understand ethnic-specific factors in GDM management and the importance of developing ethnic-tailored GDM interventions to address these disparities.

Prevalence of gestational diabetes mellitus in southern Iran (Bandar Abbas City)

OBJECTIVE

To estimate and report the prevalence of gestational diabetes mellitus (GDM) in pregnant women of Bandar Abbas, a city in southern Iran.

METHODS

From March 2002 to March 2004, 800 pregnant women underwent assessment for GDM in obstetrics clinics in Bandar Abbas. The medical history and risk factors for GDM were recorded, and the weight, height, and blood pressure were measured. All the women were screened for GDM by a 1-hour, 50-g oral glucose tolerance test (OGTT), with a cutoff point of 130 mg/dL. All patients with a "positive" screening test result underwent a 3-hour OGTT with 100 g of glucose.

RESULTS

The prevalence rate of GDM in our study was 6.3% (95% confidence interval, 4.7% to 8.4%) and 8.9% (95% confidence interval, 6.9% to 11.3%) with use of the National Diabetes Data Group and the Carpenter and Coustan criteria, respectively. The patients with GDM were significantly older than the normal group of pregnant women (28.2 +/- 5.6 years versus 24.6 +/- 5.2 years, respectively) (P<0.001). The mean number of pregnancies, systolic blood pressure, and body mass index (BMI) were significantly higher in the GDM group than in the normal pregnant women (P<0.05). Among the recorded risk factors, only age (3)25 years, history of macrosomia in previous newborns, and BMI (3)25 kg/m2 were significantly more prevalent in the GDM group than in the normal group (P<0.05). If selective screening criteria for GDM had been applied, 11.3% of patients with GDM would have been missed.

CONCLUSION

This study showed a higher prevalence of GDM in Bandar Abbas in comparison with other parts of Iran. Screening for GDM in all pregnant women in Bandar Abbas seems necessary, regardless of the presence of risk factors for GDM.

Waist circumference is the key risk factor for diabetes in Korean women with history of gestational diabetes

This study investigated relationships between various obesity indices and an onset of type 2 diabetes mellitus (TY2DM) in Korean women with history of gestational diabetes mellitus (GDM). A total of 909 women with history of GDM were enrolled from the four major hospitals, and the first postpartum follow-up examination was made at 6 weeks, and annually thereafter. During postpartum follow-up period, mean 2.13+/-1.75 years, we conducted 2h 75 g OGTT and measured glucose, insulin, c-peptide, lipid profiles, lifestyle and dietary evaluation. For obesity parameters, we measured body weight, body mass index (BMI), waist and hip circumference, subcutaneous fat thickness, body fat percent and weight using bioelectrical impedance tests. Diabetes incidence for 6 years was 12.8% and all the obesity indices were significantly higher in subjects with diabetes or glucose intolerance than those with normal glucose tolerance (p<0.001). When obesity indices were compared between <25th versus >75th percentile, the waist circumference presented with the strongest relationship (odds ratio=5.8, 95% CI 2.8-11.8). This relationship persisted, OR=3.86 (95% CI 1.8-8.2), even after adjusting for the potential confounders. This prospective study revealed that waist circumference is one of the key risk factors for the onset of diabetes in Korean women with history of GDM.

Recurrence of gestational diabetes mellitus: rates and risk factors from initial GDM and one abnormal GTT value

The recurrence rate of GDM among women in Japan who had GDM or one abnormal value on 75 g oral glucose tolerance test (OAV) during an initial pregnancy is unclear. We therefore sought to determine the recurrence rate and risk factors of recurrent GDM by evaluating 32 patients with GDM and 37 with OAV in their index pregnancies. Medical records and chemical data were compared between patients with and without GDM in their subsequent pregnancies. The recurrence rate from index GDM and OAV were 65.6% and 40.5%. Age, BMI before pregnancy, an increased weight gain between pregnancies and a short interval between pregnancies were risk factors for recurrence from the initial GDM. An increased weight gain between pregnancies and a short interval between pregnancies were risk factors of development to GDM from the initial OAV. We concluded that the control of weight gain and interval between pregnancies could be important to reduce GDM recurrence.

Screening for gestational diabetes: different cut-offs for different ethnicities?

OBJECTIVE

To examine whether screening guidelines for gestational diabetes should be modified based on ethnicity.

STUDY DESIGN

This is a retrospective cohort study of 14,565 pregnancies screened for gestational diabetes. The primary outcome of interest was the diagnosis of gestational diabetes based on the results of the 100-g glucose tolerance test. A diagnosis was determined if any 2 of the 4 values (fasting or 1-, 2-, or 3-hour postprandial) were at or above 95, 180, 155, or 140 mg/dL, respectively. Values of the 50-g glucose-loading test were examined from 130 mg/dL to 150 mg/dL. The sensitivity, specificity, false-positive rates, and positive predictive values of various glucose-loading test cut-offs were compared among whites, African Americans, Latinas, and Asians. The sensitivities and specificities were compared using receiver-operator characteristic curves.

RESULTS

Sensitivity and specificity of the glucose-loading test differ by ethnicity. Generally, African Americans achieved the highest sensitivities and specificities over the range examined. To achieve a false-positive rate of 10% for the glucose-loading test, the threshold value would be 133 mg/dL for African Americans, 140 mg/dL for whites, 143 mg/dL for Latinas, and 147 mg/dL for Asians. At the lower glucose-loading test values (130 and 135 mg/dL), Asians exhibited the highest positive predictive values (30.0% and 34.0%), whereas at higher values of the glucose-loading test (145 and 150 mg/dL), African Americans had the highest positive predictive values (46.0% and 51.5%). Throughout the glucose-loading test range, whites had the lowest positive predictive values (P < .001).

CONCLUSIONS

To maximize the sensitivity and minimize the false-positive rate of the glucose-loading test, it may be reasonable to consider varying the threshold based on ethnicity. However, modification of glucose-loading test thresholds based on maternal ethnicity merit further study to determine whether improved perinatal outcomes can be achieved.

Potential impact of American Diabetes Association (2000) criteria for diagnosis of gestational diabetes mellitus in Spain

AIMS/HYPOTHESIS

This study was carried out to determine the impact of American Diabetes Association (ADA) 2000 criteria for the diagnosis of gestational diabetes mellitus (GDM) in the Spanish population.

METHODS

Pregnant women were assigned to one of four categories: negative screenees, false-positive screenees, ADA-only-GDM (untreated) and GDM according to National Diabetes Data Group (NDDG) criteria (treated). Fetal macrosomia and Caesarean section were defined as primary outcomes, with seven additional secondary outcomes.

RESULTS

Of 9,270 pregnant women screened for GDM, 819 (8.8%) met NDDG criteria. If the threshold for defining GDM had been lowered to ADA criteria, an additional 2.8% of women would have been defined as having the condition (relative increase of 31.8%). Maternal characteristics of women with ADA-only-GDM were between those of false-positive screenees and women with NDDG-GDM. The risk of diabetes-associated complications was slightly elevated in the individuals who would have been classified as abnormal only after the adoption of ADA criteria. In addition, the ADA-only-GDM contribution to morbidity was lower than that of other variables, especially BMI.

CONCLUSIONS/INTERPRETATION

Use of the ADA criteria to identify GDM would result in a 31.8% increase in prevalence compared with NDDG criteria. However, as the contribution of these additionally diagnosed cases to adverse GDM outcomes is not substantial, a change in diagnostic criteria is not warranted in our setting.

Increasing prevalence of gestational diabetes mellitus (GDM) over time and by birth cohort: Kaiser Permanente of Colorado GDM Screening Program

OBJECTIVE

The prevalence of gestational diabetes mellitus (GDM) varies in direct proportion with the prevalence of type 2 diabetes in a given population or ethnic group. Given that the number of people with diabetes worldwide is expected to increase at record levels through 2030, we examined temporal trends in GDM among diverse ethnic groups.

RESEARCH DESIGN AND METHODS

Kaiser Permanente of Colorado (KPCO) has used a standard protocol to universally screen for GDM since 1994. This report is based on 36,403 KPCO singleton pregnancies occurring between 1994 and 2002 and examines trends in GDM prevalence among women with diverse ethnic backgrounds.

RESULTS

The prevalence of GDM among KPCO members doubled from 1994 to 2002 (2.1-4.1%, P < 0.001), with significant increases in all racial/ethnic groups. In logistic regression, year of diagnosis (odds ratio [OR] and 95% CI per 1 year = 1.12 [1.09-1.14]), mother's age (OR per 5 years = 1.7 [1.6-1.8]) and ethnicity other than non-Hispanic white (OR = 2.1 [1.9-2.4]) were all significantly associated with GDM. Birth year remained significant (OR = 1.06, P = 0.006), even after adjusting for prior GDM history.

CONCLUSIONS

This study shows that the prevalence of GDM is increasing in a universally screened multiethnic population. The increasing GDM prevalence suggests that the vicious cycle of diabetes in pregnancy initially described among Pima Indians may also be occurring among other U.S. ethnic groups.

Ethnic differences in neonatal and postneonatal mortality

OBJECTIVE

Ethnic disparities in infant mortality have been consistently documented in the United States, but these disparities are poorly understood. Although the infant mortality rate in the United States has fallen to record low rates, since 1971 the ethnic disparity between black and white infants has remained unchanged or increased. In 2001, the infant mortality rate among black infants was approximately 2.5 times higher than the rate among white and Hispanic infants. The objective of this study was to identify ethnic differences in neonatal and postneonatal mortality as well as the causes and risk factors among infants born in California.

METHODS

Secondary analysis was performed of 1,277,393 singleton infants live-born to black, Latina, and white women from the California linked birth-infant death certificate from 1995 to 1997. The dependent variables were infant death (defined as an infant who died in the first year of life [death <365 days]), neonatal death (death during the first 27 days of life), and postneonatal death (death between 28 and 364 days of life). Cause-specific neonatal and postneonatal infant mortality rates (per 100,000 live births) were calculated for each ethnic group. Chi(2) and exact test statistics were used to compare the distribution of maternal and infant characteristics and cause-of-death rates by maternal ethnicity. Logistic regression analysis was used to compute odds ratios (ORs) and 95% confidence intervals (CIs) to estimate the relationship between maternal ethnicity, maternal and infant factors, and risk of infant mortality.

RESULTS

In both the neonatal and postneonatal periods, black women had higher infant mortality rates than Latina or white women for conditions originating in the perinatal period (including respiratory distress syndrome) and symptoms, signs, and ill-defined conditions (including sudden infant death syndrome). After adjusting for maternal and infant characteristics, there were no significant ethnic differences for neonatal mortality. For postneonatal mortality, black women had a higher risk (OR: 1.25; 95% CI: 1.10-1.42) and Latina women had a lower risk (OR: 0.80; 95% CI: 0.71-0.89) compared with white women after adjusting for maternal and infant factors. In analyses of all ethnic groups combined, as well as ethnic-specific analyses, the strongest predictors of neonatal and postneonatal death were infant birth weight of <2499 g and gestational age of <33 weeks.

CONCLUSIONS

Causes of infant mortality and risk factors for infant mortality differed by maternal ethnicity, indicating a need to tailor prevention and education efforts, especially during the postneonatal period. To achieve national infant mortality goals, health professionals and policy makers should continue to emphasize the importance of early and continuous prenatal care and develop new strategies to reduce the incidence of low birth weight and premature infants. Ethnic-specific approaches may be needed to further reduce infant mortality rates and achieve our national goal to eliminate ethnic disparities in perinatal outcomes.

Prevalence of gestational diabetes mellitus in Kashmiri women from the Indian subcontinent

This prospective study was carried out to determine the prevalence of gestational diabetes mellitus (GDM) in Kashmiri women and to assess the effect of various demographic factors. Two thousand pregnant women (divided into groups A and B, being the first and last 1000 consecutive women) attending various antenatal clinics in six districts of Kashmir valley were screened for GDM by 1 h 50 g oral glucose challenge test. Four hundred and fourteen (20.8%) women (216 from group A and 198 from group B) had an abnormal screening test and proceeded to oral glucose tolerance testing. Women from group A had a 3 h 100 gram oral glucose tolerance test (OGTT) and GDM was as classified by Carpenter and Coustan. A 2 h 75 g OGTT was performed on group B subjects and WHO criteria applied for diagnosis of GDM. The overall prevalence of GDM was 3.8% (3.1% in group A versus 4.4% in group B-P-value 0.071). GDM prevalence steadily increased with age (from 1.7% in women below 25 years to 18% in women 35 years or older). GDM occurred more frequently in women who were residing in urban areas, had borne three or more children, had history of abortion(s) or GDM during previous pregnancies, had given birth to a macrosomic baby, or had a family history of diabetes mellitus. Women with obesity, hypertension, osmotic symptoms, proteinuria or hydramnios had a higher prevalence of GDM.

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.

Prevalence and risk factors for gestational diabetes assessed by universal screening

In order to evaluate the prevalence of gestational diabetes mellitus (GDM) and the presence of risk factors for GDM, we conducted a retrospective study of a cohort of Italian women. In addition, we compared universal versus selective screening to validate the ADA's recommendations in our population. From June 1st, 1995 to December 31st, 2001, universal screening for GDM was performed in 3950 women. The glucose challenge test (GCT) was positive (GCT+) in 1389 cases (35.2%). The 1-h glucose level after GCT enabled us to diagnose GDM directly in 24 pregnant women. Oral glucose tolerance test (OGTT) was performed in 1221 GCT+ women (144 cases with GCT+ dropped out) and GDM was diagnosed in 284 (23.2%) of them. OGTT was also performed in 391 randomly chosen, women from the GCT negative (GCT-) group. In this last group 25 (6.3%) women had GDM. Thus, the total number of subjects with GDM was 333 out of 3806 with a prevalence of 8.74% in the entire cohort. Assuming that the rate of GDM observed in the random sample of GCT- women is applicable to the whole group of 2561 GCT- women, then 161 GCT- patients could also have GDM. This will further increase the estimated prevalence for the whole cohort up to 12.3% (i.e. 469 out of 3806 pregnant women). There were 236 (5.6%) women with a low risk for GDM (normal weight, age less than 25 years and without a family history of diabetes). In this group we found 34 cases and five cases with positive screening test and GDM, respectively. Thus, if we excluded low risk women from the screening test, as suggested by ADA recommendations, only five women with GDM would have been missed. However, about 95% of our population were at medium or high risk for GDM and, therefore, would have been screened. The rate of GDM was significantly higher in women with a positive history of diabetes, increasing age, previous pregnancies, pre-pregnancy overweight and short stature. After logistic regression analysis, GDM diagnosis was significantly correlated with age (P<0.0001), pre-pregnancy BMI (P<0.0001), weight gain (P<0.0001) and family history of diabetes (P<0.01).

The number of abnormal plasma glucose values in the oral glucose tolerance test and the feto-maternal outcome of pregnancy

OBJECTIVE

With respect to the feto-maternal outcome of pregnancy both appropriate screening and treatment of gestational diabetes mellitus (GDM) remain a matter of debate. Furthermore, the importance of only one abnormal glucose value at the glucose tolerance test (GTT) is still discussed, including the term "gestational impaired glucose tolerance" with normal fasting but an increased 2h postprandial glucose value.

STUDY DESIGN

We have evaluated the feto-maternal outcome of pregnancy in 152 women with abnormal glucose values during the oral 100g GTT. The data were analysed with respect to the number of abnormal GTT values and compared to age- and body mass index (BMI)-matched control groups including 304 women with normal GTT values.

RESULTS

A positive family history of diabetes was found in 24.4% of the GDM women and in 16.4% of the control group. In 45.9% of the women with abnormal GTT values glucose target levels could be obtained by dietary management, 54.1% required additional insulin therapy. Insulin therapy was administered in 32.8% of the women with one abnormal GTT value, in 65.0% of the women with two abnormal values and in 83.3% of the women with three abnormal values. Compared to the age- and BMI-matched control group the percentage of women with hypertension was increased in women with one, two and three abnormal GTT values. The percentage of LGA and macrosomic infants was significantly increased only in women with three abnormal GTT values. Women with one, two or three abnormal GTT values revealed an increased percentage of caesarean section compared to the control group.

CONCLUSIONS

Our results show that women with three abnormal GTT values are at an overall increased risk with respect to the feto-maternal outcome of pregnancy. Compared to the control group also women with only one abnormal GTT value revealed an increased risk indicating a need for further control and therapy.

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.

Prevalence of gestational diabetes mellitus detected by the national diabetes data group or the carpenter and coustan plasma glucose thresholds

OBJECTIVE

In 2000, the American Diabetes Association proposed the adoption of the Carpenter and Coustan criteria for diagnosis of gestational diabetes mellitus (GDM). The Carpenter and Coustan cutoffs are lower than the previously recommended National Diabetes Data Group (NDDG) values and would result in higher prevalence of GDM. Our aim is to estimate the magnitude of change in prevalence of GDM using the Carpenter and Coustan thresholds as compared with the NDDG thresholds by age and ethnicity.

RESEARCH DESIGN AND METHODS

Cross-sectional study of 28,330 women aged 14-49 years who gave birth in 1996 and were members of the Northern California Kaiser Permanente Medical Care Program. Age, ethnicity, screening, and diagnostic test results were assessed from computerized hospitalization and laboratory systems.

RESULTS

A total of 26,481 (94%) women were screened using a 50-g, 1-h oral glucose tolerance test, and 4,190 women underwent a diagnostic 100-g, 3-h oral glucose tolerance test after an abnormal screening. Overall, the GDM prevalence among screened women was 3.2% (95% CI 3.0-3.4) by NDDG and 4.8% (95% CI 4.5-5.1) by Carpenter and Coustan criteria, and based on either threshold, it increased with age (P < 0.001). The age-adjusted GDM prevalence by NDDG and Carpenter and Coustan criteria, respectively, was 5.0 and 7.4% in Asians, 3.9 and 5.6% in Hispanics, 3.0 and 4.0% in African-Americans, and 2.4 and 3.8% in whites. Proportional increments were larger in women aged <25 years (70%) and in whites (58%).

CONCLUSIONS

-The prevalence of GDM increased, on average, by 50% with use of the Carpenter and Coustan thresholds. Relative increments were greater in low-risk age and ethnic groups. This information would be useful for clinical settings in predicting cost of GDM based on demographic characteristics of the population.