The diagnosis and classification of gestational diabetes mellitus: Is it time to change our tune?

Objective: This study was designed to determine the impact on our population of adopting the Carpenter and Coustan criteria for gestational diabetes mellitus in place of the currently used National Diabetes Data Group criteria, to review the evidence supporting replacement of the National Diabetes Data Group criteria with the Carpenter and Coustan criteria, and to propose analogous diagnostic criteria for diabetes in pregnant and nonpregnant women. Study Design: The National Diabetes Data Group criteria and the proposed Carpenter and Coustan criteria were both used to retrospectively review medical records of patients screened for gestational diabetes mellitus during 1995 and 1996 in the Kaiser Permanente Northwest Division. Computerized search was performed on automated data systems and software was used for statistical analyses. A MEDLINE review of relevant literature was conducted. Results: Of 8857 pregnant women screened for gestational diabetes in 1995 and 1996, 284 (3.21%) met the National Diabetes Data Group criteria, whereas 438 (4.95%) met the Carpenter and Coustan criteria. We estimate that in our population use of the Carpenter and Coustan criteria in 1996 could at best have reduced the prevalence of infants weighing ≥4000 g from 17.1% to 16.9% and the prevalence of infants weighing ≥4500 g from 2.95% to 2.91%. Conclusions: Replacing the National Diabetes Data Group criteria with the Carpenter and Coustan criteria would increase by 54% the number of pregnant women with a diagnosis of gestational diabetes mellitus and would also increase costs, while only minimally affecting prevalence of infant macrosomia. The medical literature does not provide compelling evidence for adopting the Carpenter and Coustan criteria. Standardization of both measurement of venous plasma glucose level and diagnostic criteria for gestational diabetes mellitus is an important goal. Parallel criteria for diagnosis and classification of diabetes mellitus in pregnant and nonpregnant women should be developed. (Am J Obstet Gynecol 1999;180:1560-71.)     

Glucose screening in Mexican-American women

OBJECTIVE: We sought to describe the predictive value for gestational diabetes mellitus (GDM) using different glucose challenge test thresholds in Mexican-American women. METHODS: A prospective population-based study of 6,857 gravid women, who were tested with a 50-g glucose challenge test at 24-28 weeks of gestation, was performed. A screening value of 130 mg/dL or greater was followed by a 3-hour, 100-g oral glucose tolerance test. Gestational diabetes mellitus was diagnosed by 2 or more abnormal values using the Carpenter and Coustan criteria. For purpose of analysis, GDM diagnosis was categorized with glucose challenge test values in 10-mg/dL increments. A comparison between Carpenter-Coustan and the National Diabetic Data Group criteria for GDM diagnosis was performed for each glucose challenge test threshold category. Sensitivity and specificity for GDM diagnosis were further calculated for different glucose challenge test thresholds (130, 135, and 140 mg/dL). RESULTS: Overall, GDM was diagnosed in 469 of 6,857 (6.8%) women, and one abnormal oral glucose tolerance test value was tested in 351 of 6,857 women (5.1%). Normal glucose challenge test results (threshold less than 130 mg/dL) were obtained in 4,316 of 6,857 women. An elevated glucose challenge test value increases the risk of GDM, but even in high glucose challenge test thresholds (more than 180 mg/dL), the predictive value for GDM was only 50%. The sensitivity and specificity for GDM diagnosis using 3 different glucose challenge test thresholds were as follows: threshold 130 mg/dL or more: 97% and 63%; threshold 135 mg/dL or more: 91% and 73%; and threshold 140 mg/dL or more: 85% and 78%, respectively. CONCLUSION: Data suggests that an elevated glucose challenge test level cannot be used as a single diagnostic tool for GDM even in high test thresholds. A threshold of 130 mg/dL may be recommended as a screening threshold for GDM in Mexican-American women. LEVEL OF EVIDENCE: II-3     

Gestational diabetes mellitus in Chinese women.

OBJECTIVE: To determine whether foreign diagnostic criteria for the diagnosis of gestational diabetes mellitus (GDM) are suitable for Chinese pregnant women. METHODS: The study participants were 340 pregnant women receiving obstetric care at the Shanghai Jiaotong University-Affiliated Sixth People's Hospital in Shanghai, China. The normal-pregnancy group comprised 190 women with no risk factor for GDM and the high-risk pregnancy group comprised 150 women who had at least one high-risk factor for GDM. All women took the diagnostic 100-g, 3-h oral glucose tolerance test (100-g 3-h OGTT) between 24 and 28 weeks of pregnancy. The results of the 100-g 3-h OGTT were classified according to three different sets of diagnostic criteria: (1) new, "Chinese" diagnostic criteria based on the results from the 100-g 3-h OGTT performed in the 190 healthy participating women; (2) the Carpenter and Coustan criteria; and (3) the National Diabetes Data Group (NDDG) criteria. Venous plasma glucose (VPG) was measured by the glucose oxidase method. A consistency check was used for analysis. Obstetric and neonatal outcomes were recorded. RESULTS: With 97.5% as the statistical cutoff value for the 100-g 3-h OGTT, the new diagnostic criteria for this study, based on data obtained from the 100-g 3-h OGTT performed on the 190 participating healthy pregnant women, were 5.2, 10.3, 8.9, and 7.7 mmol/L at 0, 60, 120, and 180 min. The e value was 0.83 for the new criteria vs. the Carpenter and Coustan criteria (P<0.001) and 0.70 for the new criteria vs. the NDDG criteria (P<0.001). In women with GDM and gestational-impaired glucose tolerance (GIGT), the incidence rates of macrosomia by the new criteria and the Carpenter and Coustan criteria were similar, but higher than the rates calculated with the NDDG criteria (P<0.05). CONCLUSION: With venous plasma glucose level measured by the glucose oxidase method, the Carpenter and Coustan criteria are applicable to Chinese pregnant women for diagnosis of GDM.     

Universal versus selective gestational diabetes screening: application of 1997 American Diabetes Association recommendations.

OBJECTIVE: We sought to evaluate the impact of the 1997 American Diabetes Association gestational diabetes mellitus screening guidelines applied to a universally screened population. STUDY DESIGN: A retrospective analysis of 18,504 women universally screened for gestational diabetes mellitus at Mayo Clinic, Rochester, between January 1, 1986, and December 31, 1997, was performed. Diabetic screening consisted of plasma glucose determination 1 hour after a 50-g oral glucose challenge. Diagnosis of gestational diabetes mellitus was based on National Diabetes Data Group criteria. RESULTS: Of 564 cases of gestational diabetes mellitus diagnosed during the study period, 17 (3.0%) would have been missed under the 1997 American Diabetes Association selective screening guidelines while exempting only 10% of this predominantly white population from screening. Screening only women >/=25 years old would have detected 90.4% of gestational diabetes mellitus cases, whereas the addition of the remaining 3 screening criteria combined would have detected only an additional 6.6% of cases. CONCLUSIONS: The proportion of patients with gestational diabetes mellitus that would remain undiagnosed under the 1997 American Diabetes Association screening guidelines would be relatively small in our population. However, implementation of these guidelines would decrease the number of screens by only 10% while adding significant complexity to the screening process. Youth appears to be the most significant protective factor for gestational diabetes mellitus in our population.     

Effects of new criteria for type 2 diabetes on the rate of postpartum glucose intolerance in women with gestational diabetes.

OBJECTIVE: Our purpose was to determine the impact of the 1997 American Diabetes Association diagnostic criteria for type 2 diabetes mellitus on the rate of postpartum glucose intolerance in women with gestational diabetes. STUDY DESIGN: Women identified as having gestational diabetes were instructed to undergo a 75-g, 2-hour glucose tolerance test 4 to 6 weeks after delivery. The results were retrospectively categorized with both the 1979 National Diabetes Data Group criteria and those recommended by the American Diabetes Association in 1997. RESULTS: Though the rate of overt diabetes mellitus did not increase when the 1997 American Diabetes Association criteria were used (7.8% vs 5.6%, P = not significant), the rate of impaired glucose metabolism was higher (20.1% vs 5%, P <.001). Most women (28/30, 93%) with a nondiagnostic glucose tolerance test result by the older criteria had abnormal results by the newer criteria. Fifty women had abnormalities of glucose metabolism under 1997 American Diabetes Association criteria; 34% of these women had fasting plasma glucose values in the normal range. Of the 25 women with impaired glucose tolerance, 16 (64%) had only an abnormal 2-hour value, with normal fasting glucose values. CONCLUSIONS: The rate of postpartum abnormalities in glucose metabolism more than doubles when the 1997 American Diabetes Association criteria are applied; more women are identified with lesser degrees of impairment. However, relying on fasting glucose levels alone, without glucose tolerance testing, may miss one third of women with such abnormalities.     

Gestational diabetes: comparision of the carpenter and the coustan thresholds with the new thresholds of Turkish women and implications of variations in diagnostic criteria

Objective: To find optimal 100-g 3-h oral glucose tolerance test (OGTT) threshold levels for diagnosis of gestational diabetes (GDM) in Turkish pregnant women. Methods: This study was conducted with 808 women screened for GDM between 24–28 weeks of gestation using the 1-h 50-g glucose challenge test (GCT) with a subsequent 3-h 100-g OGTT for confirmation if screen was positive. The glucose values obtained were analysed by both the Carpenter and Coustan (C&C criteria) and National Diabetes Data Group (NDDG) criteria for the diagnosis of GDM and IGT. Optimal OGTT cutoff values for Turkish population were calculated by ROC curve analysis. Results: The new diagnostic criteria, based on the result of the 100-g OGTT obtained from the healthy pregnant women, were 82.5, 171.5, 151.5, and 111.5?mg/dl at 0, 1, 2, and 3?h. The prevalence of GDM was 15.7% by the new criteria, 8.1% by C&C criteria, and 5.6% by the NDDG criteria. According to new criteria, 7.7% of infants of diabetic mothers had macrosomia. This ratio was 2.6% for non diabetic women. Conclusions: Ethnic differences, enviromental factors and nutritional habits may effect development of GDM. Application of some pre-determined nomograms to all races and ethnic groups can lead errors.     

The twentieth century: The century of progress and medicine

The standard criteria for the diagnosis of gestational diabetes (GDM) is based on two abnormal values of a 3-h-100-g oral glucose tolerance test (GTT). Although a markedly elevated 1 h–50-g screen value has been suggested to support a diagnosis of GDM, limited data are available to substantiate this empiric observation. Our purpose was to examine the utility of various 50-g screen cutoff values in establishing the diagnosis of gestational diabetes.

We identified 422 gravidas with a positive 50-g screen (≥135 mg/dl) who underwent additional glucose testing. GDM was defined according to the National Diabetes Data Group (NDDG) standards for the 3-h GTT. An analysis employing the criteria of Carpenter and Coustan was performed for comparison. If a patient had an elevated 50-g value and no 3-h GTT was performed, a fasting serum glucose ≥140 mg/dl was considered evidence of gestational diabetes.

One hundred twenty four (29.4%) had GDM as defined by the NDDG criteria; this increased to 161 (38%) when the diagnosis was based on Carpenter and Coustan's criteria. The mean (≥SD) gestational age at screening was 24 ± 7 weeks. As expected, the prevalence of GDM increased in relation to an increasing 50-g value. All subjects with a 50-g screen < 216 mg/dl had evidence of gestational diabetes and required insulin for glycemic control.

Patients with a 50-g screen ≥220 mg/dl do not all require a 3-h GTT. Those with a fasting serum glucose of ≥140 mg/dl may begin diet therapy, glucose monitoring, and insulin as indicated. If the fasting serum glucose is < 140 mg/dl, a 3-h GTT should be performed for confirmation of GDM. This approach will facilitate rapid therapeutic intervention and reduce the cost of care in this subset of patients. Gravidas with a very high 50-g screen are at significant risk of requiring insulin to maintain euglycemia during pregnancy.     

Comparison of glucose polymer and glucose for screening and tolerance tests in pregnancy

Forty-eight of 100 pregnant women received a 100-g (nonfasting) glucose screening test at about 28 weeks' gestation, followed by a 100-g glucose tolerance test. Another 52 received a 100-g (nonfasting) glucose polymer screening test followed by a 100-g glucose polymer tolerance test. Mean plasma glucose one hour after the glucose screening test was significantly lower than after the glucose polymer screening test. A further 178 women received a glucose polymer screening test and a glucose polymer tolerance test (230 in total). These women and the infants they delivered were studied to derive diagnostic criteria for the 100-g glucose polymer tolerance test by correlating maternal carbohydrate tolerance with indexes of neonatal metabolic performance, and to determine an adequate method of screening for carbohydrate intolerance of pregnancy (gestational diabetes). Diagnostic criteria similar to those of O'Sullivan and Mahan were also developed for the glucose polymer tolerance test. These values are up to 5% lower than those recommended by the National Diabetes Data Group (1979) for the 100-g glucose tolerance test.     

A comparison between a 75-g and 100-g oral glucose tolerance test in pregnant women.

OBJECTIVES: To test the validity of a 75-g, 2-h oral glucose tolerance test (OGTT) for diagnosing gestational diabetes mellitus (GDM) using the criteria and reference values suggested by the American Diabetes Association for the 100-g, 3-h OGTT. METHODS: The results of a 75-g, 2-h OGTT were compared with those of a 100-g, 3-h OGTT in 42 pregnant women. The women's mean+/-S.D. age and gestational age were 33.6+/-5.4 years and 28.2+/-4.2 weeks, respectively. Each subject was randomly scheduled within 1 week for both the 75-g and 100-g OGTTs. RESULTS: The mean plasma glucose concentrations at 1, 2, and 3 h during the 100-g OGTT were significantly higher than those during the 75-g OGTT. Using the Carpenter and Coustan criteria, the prevalence of GDM was 21.4% when using the 100-g, 3-h OGTT, whereas it was found to be at only 7.1% when using the 75-g, 2-h OGTT. CONCLUSIONS: Plasma glucose responses during the 75-g OGTT were found to be lower than those during the 100-g OGTT. When using the same diagnostic criteria, the prevalence of GDM was also found lower using the 75-g glucose load. It would therefore not be appropriate to use the 75-g OGTT for diagnosing GDM using the criteria and reference values of the 100-g OGTT. To give a comparable prevalence of GDM, the threshold of abnormal plasma glucose levels of the 75-g OGTT would need to be lower than that of the 100-g OGTT.     

Screening for gestational diabetes mellitus by a model based on risk indicators: a prospective study

OBJECTIVE: This study was performed to prospectively evaluate a screening model for gestational diabetes mellitus on the basis of clinical risk indicators. STUDY DESIGN: In a prospective multicenter study with 5235 consecutive pregnant women, diagnostic testing with a 2-hour 75-g oral glucose tolerance test was routinely performed in women with risk indicators and offered to women without risk indicators as part of the study. RESULTS: Forty-four percent of the women underwent testing, 43% declined participation, 6% did not speak Danish, and 7% could not be contacted. By extrapolation of the results from tested women to the whole group in question, a 2.4% prevalence of gestational diabetes mellitus was calculated. Sensitivity and specificity of the model was 80.6 (73.7-87.6) and 64.8 (63.5-66.1), respectively (95% CIs). CONCLUSION: Under ideal conditions, sensitivity of the model was comparable with universal screening by fasting glucose or a 1-hour 50-g glucose challenge test. Both screening and diagnostic testing could be avoided in two thirds of all pregnant women.     

Staying with old guidelines

Gestational diabetes mellitus is associated with increased neonatal morbidities and higher cesarean delivery rates; women with gestational diabetes mellitus are at increased risk for type II diabetes mellitus later in life. The current recommendation for screening includes a glucose tolerance test either early in pregnancy and/or at 24-28 weeks' gestation followed by a diagnostic 100-g oral 3-hour glucose tolerance test with a rate of 5%. The results of a large prospective observational study (HAPO study) and 2 randomized trials lead the International Association of Diabetes in Pregnancy Study Group to recommend a 1-stage screening and diagnosis method that includes a 75-g 2-hour glucose tolerance test that will result in an 18% gestational diabetes mellitus rate. However, there is uncertainty about the clinical implications of the adoption of the latter recommendation.     

Abnormal glucose tolerance is associated with preterm labor and increased neonatal complications in Taiwanese women

ObjectiveTo investigate the relationship between abnormal degrees of oral glucose tolerance test (OGTT) results and pregnancy outcomes.Materials and methodsA total of 7513 singleton pregnancies screened for gestational diabetes mellitus were enrolled in this retrospective observational study. The pregnancy outcomes of six different groups with different degrees of glucose intolerance using the OGTT were compared [both the National Diabetes Data Group (NDDG) and Carpenter and Coustan (C&C) criteria were used]. The pregnancies were classified into the following groups: the normal group, consisting of pregnancies with a negative 50-g glucose challenge test (GCT), and Grade 0, 1, 2, 3 and 4 groups, consisting of pregnancies with positive 50-g GCT, and abnormal values of 0, 1, 2, 3 and 4 from the 100-g OGTT, respectively.ResultsThe adjusted odds ratios (95% confidence interval) for preterm labor and admission to the neonatal intensive care unit (NICU) were shown to be increased in the Grade 4 groups [3.31 (1.47–7.43) and 6.31 (3.14–12.70) by the NDDG criteria; 4.13 (2.30–7.43) and 5.25 (3.00–9.19) by the C&C criteria] compared with the normal group.ConclusionThe results indicated an increased risk for preterm labor and admission to the NICU as the abnormal value of the OGTT increased.     

Gestational diabetes mellitus and lesser degrees of pregnancy hyperglycemia: association with increased risk of spontaneous preterm birth

OBJECTIVE: To investigate whether different degrees of maternal glucose intolerance are associated with the risk of spontaneous preterm birth. METHODS: We performed a cohort study of 46,230 pregnancies screened by a 50-g, 1-hour oral glucose tolerance test between 24 and 28 gestation weeks at the Northern California Kaiser Permanente Medical Care Program. Spontaneous preterm birth was defined as an infant born at less than 37 gestation weeks with at least one of the following: spontaneous labor, preterm premature rupture of membranes, or incompetent cervix. Glucose tolerance status was categorized as normal screening (1-hour plasma glucose less than 140 mg/dL), abnormal screening (1-hour plasma glucose of at least 140 mg/dL with a normal diagnostic 100-g, 3-hour oral glucose tolerance test result), Carpenter-Coustan (plasma glucose measurements during the diagnostic oral glucose tolerance test met the thresholds but were lower than the National Diabetes Data Group thresholds), and gestational diabetes mellitus (GDM) by the National Diabetes Data Group criteria. RESULTS: One thousand nine hundred fifty-six spontaneous preterm births occurred. Age-adjusted incidences of spontaneous preterm birth were 4.0% in normal screening, 5.0% in abnormal screening, 6.7% in Carpenter-Coustan, and 6.7% in GDM. In a logistic regression model adjusted for age, race-ethnicity, preeclampsia-eclampsia-pregnancy-induced hypertension, chronic hypertension, polyhydramnios, and birth weight for gestational age, pregnancies with abnormal screening, Carpenter-Coustan, and GDM had a significantly higher risk of spontaneous preterm birth than pregnancies with normal screening (relative risk [95% confidence interval]: 1.23 [1.08, 1.41], 1.53 [1.16, 2.03], and 1.42 [1.15-1.77], respectively). CONCLUSION: The risk of spontaneous preterm birth increased with increasing levels of pregnancy glycemia. This association was independent of perinatal complications that could have triggered early delivery.     

Clinical predictors for a high risk for the development of diabetes mellitus in the early puerperium in women with recent gestational diabetes mellitus

OBJECTIVE: The purpose of this study was to identify which maternal, antepartum, or neonatal clinical parameters were predictive for a high risk of diabetes mellitus in the puerperium in women with recent gestational diabetes mellitus and to calculate the associated diabetes mellitus rates and odds ratios. STUDY DESIGN: One thousand six hundred thirty-six women underwent an oral glucose tolerance test within 1 to 4 months of delivery. Demographic, historic, and antenatal glycemic parameters and neonatal outcome parameters were tested by univariate and multivariate logistic regression for risk of postpartum diabetes mellitus. Continuous variables were divided into quartiles that compared the upper to lower quartile adjusted odds ratio and prevalence of diabetes mellitus. RESULTS: Postpartum diabetes mellitus was diagnosed in 230 women (14.1%) according to the American Diabetes Association criteria (1997). No maternal demographic or neonatal parameters were significantly associated with diabetes mellitus. The final model of independent predictors in decreasing significance included the highest fasting plasma glucose level during pregnancy, any fasting plasma glucose level of > or = 105 mg/dL (class A(2)), the area under the curve of pregnancy oral glucose tolerance test, gestational age at diagnosis, previous gestational diabetes mellitus history, and 50-g glucose challenge test results. The fasting plasma glucose level was the best discriminator, with a 21-fold (95% CI, 4.6-96.3) increased odds ratio comparing the 4th quartile (fasting plasma glucose level, >121 mg/dL; diabetes mellitus rate, 36.7%) to 1st quartile (fasting plasma glucose level, < 95 mg/dL; diabetes mellitus rate, 0.5%). The presence of previous gestational diabetes mellitus or current class A(2) gestational diabetes mellitus approximately doubled the odds ratio for diabetes mellitus. The odds ratio increased 3- to 4-fold when the area under the curve was > or = 33.36 min small middle dot g/dL (4th quartile) or the glucose challenge test was > or = 155 mg/dL (2nd-4th quartiles) and decreased > 50% if gestational diabetes mellitus was diagnosed at > 27 weeks (3rd-4th quartile). CONCLUSION: During pregnancy, the highest fasting glucose level, followed by the severity of glucose intolerance, and earlier gestational diabetes mellitus diagnosis were the best predictors for postpartum diabetes mellitus. Diabetic education should begin during pregnancy, especially for women who are identified to be at a high risk when they are highly motivated and under medical care.     

Perinatal outcomes in gestational diabetes: a comparison of criteria for diagnosis

OBJECTIVE: The purpose of this study was to compare the perinatal outcomes of women after diagnosis of gestational diabetes by the current American College of Obstetricians and Gynecologists-National Diabetes Data Group recommendations with outcomes after diagnosis by the American Diabetes Association criteria. STUDY DESIGN: We identified records of 242 women who had had the standard 3-hour oral glucose tolerance test between 1995 and 1999 at the Regional Medical center in Memphis. Patients were categorized into 1 of 3 groups as follows: euglycemic control subjects (n = 69), subjects with gestational diabetes diagnosed by the National Diabetes Data Group criteria (n = 130), and subjects with gestational diabetes diagnosed by the American Diabetes Association criteria (n = 43). Maternal and infant charts were reviewed. Primary outcomes included frequency of cesarean delivery, preeclampsia, and macrosomia. In univariate analysis the chi2 test was used to compare group differences, and in multivariate analysis we used stepwise logistic regression and controlled for confounding factors. RESULTS: No differences existed among the 3 groups regarding maternal race, body mass index, history of preeclampsia, or family history of diabetes. The frequency of overall cesarean delivery, of cesarean delivery for macrosomia or arrest disorder, of preeclampsia, and of macrosomia did not differ significantly among the 3 groups. Neonatal hypoglycemia was more frequent in the groups with a diagnosis by the American Diabetes Association criteria (23.3%) and by the National Diabetes Data Group criteria (16.2%) than in the control subjects (7.2%), reaching near significance (P =.057). In the multivariate analysis, cesarean delivery for macrosomia or an arrest disorder correlated negatively with parity and positively with body mass index. Preeclampsia was associated with African American race and body mass index; macrosomia correlated with a history of macrosomia and familial diabetes. Neonatal hypoglycemia was more common in the American Diabetes Association group (odds ratio, 2.45; 95% confidence interval, 1.004-5.97) and in the insulin-requiring National Diabetes Data Group category (odds ratio, 3.71; 95% confidence interval, 1.20-11.44). CONCLUSION: The benefits of defining an additional high-risk population of women with gestational diabetes by the American Diabetes Association criteria are unclear. Further large-scale prospective clinical trials are required.     

Gestational diabetes: an alternative, patient-friendly approach for using the diagnostic 100-g OGTT in high-risk populations

Objective: To simplify the 100-g oral glucose tolerance test (OGTT) for making a diagnosis of gestational diabetes mellitus (GDM). Methods: During a 6-year period, 6,801 pregnant women underwent the 3-h, 100-g OGTT in a high-risk, multiethnic population. All these women had either a positive glucose challenge test/clinical history or were part of a universal screening protocol. The area (AUC) under the receiver-operating characteristic curve was used to compare the performance of the fasting plasma glucose (FPG), 1-h, 2-h and 3-h glucose values for GDM diagnosis. Ideal cut-offs of the best performing glucose value alone and in combination were used to find the best predictor for GDM with minimal loss of sensitivity and specificity. Results: Using the American Diabetes Association criteria, 2,127 (31.3%) women were classified as having GDM. The 2-h value was the best performing (AUC 0.933) glucose value; at an optimal cut-off of ≥8.6 mmol/l, the sensitivity was 83.6% with a specificity of 92.8%. It did not achieve sufficient collective specificity and sensitivity at various thresholds to be useful. However, in combination with FPG (either FPG ≥5.3 mmol/l or 2-h ≥8.6 mmol/l) or (either FPG ≥5.6 mmol/l or 2-h ≥8.6 mmol/l), the sensitivity/specificity were 98.5%/84.7% and 92.5%/89.3%, respectively. Conclusion: An abbreviated 100-g OGTT, using only the FPG and 2-h glucose value, may be a useful alternative in high-risk populations to make a diagnosis of GDM by being cost-effective and patient-friendly.     

The "breakfast tolerance test": screening for gestational diabetes with a standardized mixed nutrient meal

In a group of 50 presumed normal pregnant women and 20 known gestational diabetic women, all in the early third trimester, the function of a standard 50 gm, 1-hour screening test for gestational diabetes was compared with that of a plasma glucose level determined 1 hour after the ingestion of a standard 600 kcal mixed nutrient breakfast (breakfast tolerance test). The mean plus 2 SD for the breakfast tolerance test was 120 mg/dl. If this were used as the threshold for a screening test, 75% of cases of gestational diabetes would be identified (sensitivity), while 94% of normal pregnant women would be excluded (specificity). A threshold of 100 mg/dl yields a sensitivity of 96% and a specificity of 74%. These results are compared with those for the standard 50 gm glucose challenge.     

Evaluation of the WHO criteria for 75 g oral glucose tolerance test in pregnancy

Summary. A group of pregnant women at high risk of developing diabetes in pregnancy had paired oral glucose tolerance tests (OGTT) using a 100 g load followed by 75 g load. When the World Health Organization (WHO) criteria and the National Diabetes Data Group (NDDG) criteria were compared, the 2-h plasma glucose value after the 100 g load was the most discriminative in differentiating those with normal glucose tolerance, impaired glucose tolerance and gestational diabetes mellitus. When only the 2-h plasma glucose values were assessed, the WHO test (75 g: 8 mmol/1) agreed with the NDDG test (100 g load: 9·2 mmol/1) in the diagnosis of glucose intolerance in 60% of subjects only. Using the same criteria at 2-h (8 mmol/1) the agreement between these tests was 47%. Reducing the glucose load from 100 g to 75 g produced a reduced glucose response in 49% of the subjects, with a significant decrease in the area under the glucose response curve.     

Adiponectin and glucose levels in women with negative or false positive glucose challenge test

OBJECTIVE: To determine whether there is a correlation between adiponectin levels and glucose levels in women screened for gestational diabetes mellitus by means of a 50-g oral glucose challenge test, and to examine the difference in adiponectin levels between women who tested negative, and those who tested false positive. We further calculated the correlations between adiponectin levels and glucose levels, body mass index, gestational age and maternal age. METHODS: A case control study included 171 mothers with negative or false positive results in the 1-h 50-g glucose challenge test at 24-28 gestational weeks. Serum adiponectin levels were determined by radioimmunoassay at the time of the glucose challenge test. RESULTS: There was a significant difference between women who tested negative at screening, and those who tested false positive with respect to age, prepregnancy body weight and body mass index, and adiponectin levels. Correlation analysis showed adiponectin levels to be negatively correlated to glucose levels (r=-0.193, P=0.011). To examine the association between glucose levels, adiponectin levels and demographic variables, multiple linear regression analysis was carried out. Prepregnancy body mass index and age accounted for 14.6% of the variance in the glucose challenge test. Adiponectin levels did not contribute independently to the variation in glucose levels. A further multiple linear regression analysis was undertaken to investigate the association between adiponectin levels and age, prepregnancy body mass index and glucose levels in the glucose challenge test. In this regression model, prepregnancy body mass index and age explained 12.1% of the variance in adiponectin levels. CONCLUSIONS: In conclusion, our study indicated a negative correlation between adiponectin and glucose levels in women screened for gestational diabetes mellitus by a glucose challenge test. We further found that maternal age and body mass index were independent risk factors for a false positive glucose challenge test. Reduced adiponectin levels in women who tested false positive on the glucose challenge test were dependent on advanced age and higher body mass index.     

Management of diabetes mellitus by obstetrician-gynecologists

OBJECTIVE: To compare practice patterns of the American College of Obstetrician and Gynecologists (ACOG) Fellows for the diagnosis and treatment of gestational diabetes mellitus (GDM) and type 1 diabetes mellitus with current ACOG recommendations and prior published series. METHODS: We sent a questionnaire to 1,398 practicing ACOG Fellows and Junior Fellows, 398 of whom comprise the Collaborative Ambulatory Research Network. Responses were evaluated by age and sex to assess differences in practice. RESULTS: Younger physicians were more likely to treat pregnant patients. Ninety-six percent of obstetricians routinely screen for GDM, nearly all by using a 50-g glucose 1-hour oral test. Nearly 60% of respondents establish the diagnosis of GDM using the National Diabetes Data Group criteria. In addition to medical nutrition therapy, almost 75% of respondents recommend exercise for patients with GDM. Approximately 60% of respondents reported that all of their patients with GDM self-monitor their blood glucose. When medical nutrition therapy is ineffective for their patients with GDM, 82% of respondents initially prescribe insulin, whereas 13% begin with glyburide. Nearly 75% of respondents routinely perform a postpartum evaluation of glucose tolerance in the patient with GDM. Most obstetricians manage the glucose control of their patients with type 1 diabetes mellitus themselves. CONCLUSION: Practicing obstetrician-gynecologists have incorporated recent recommendations into their practice patterns for both GDM and type 1 diabetes mellitus, including patients' self-monitoring of blood glucose, exercise, and postpartum testing in GDM. LEVEL OF EVIDENCE: III