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.     

Screening for gestational diabetes mellitus in adolescent Hispanics

Objective: To determine the incidence of gestational diabetes mellitus in an adolescent Hispanic population and calculate the cost of screening.Methods: A retrospective chart review of deliveries to adolescent (<20 years old) Hispanic women from January 1991 through May 1996 was performed. The incidence of gestational diabetes mellitus (GDM) was determined and the cost of screening calculated.Results: Three hundred twenty-six adolescent Hispanic women were screened for GDM with a 1-hour 50-g oral glucose tolerance test at an average gestational age of 26 weeks (range 11–39 weeks), at a cost of $26 per test. Thirty (9.2%) had positive screens defined as a plasma glucose level of ≥140 mg%. Three-hour 100-g oral glucose tolerance tests were performed on those with positive screens, at a cost of $124 per test. Five women were diagnosed with GDM, an incidence of 1.5%. The cost to diagnose each case of GDM was $2,569.Conclusion: The incidence of GDM in this population is low, and therefore universal screening of Hispanic adolescents may be unwarranted and cost prohibitive. Large prospective trials evaluating maternal and neonatal outcomes would provide the best means to assess the value of screening.     

Gestational diabetes mellitus: metabolic and blood glucose parameters in singleton versus twin pregnancies.

OBJECTIVES: This study compared the frequency, glucose tolerance test results, and parameters of blood glucose control in twin and singleton pregnancies associated with gestational diabetes mellitus and carbohydrate intolerance. STUDY DESIGN: Twin and singleton pregnancies associated with gestational diabetes mellitus and carbohydrate intolerance were compared as follows: frequency, maternal age, weight, 1-hour screen, glucose tolerance test results, posttreatment blood glucose values, insulin requirement, and insulin dose. Statistical analysis included the chi(2) and Student t tests. RESULTS: Gestational diabetes mellitus was increased in twins (7.7% vs 4.1%; P <.05). The maternal weight at first visit was significantly less, and the 3-hour glucose tolerance test value was significantly greater than that for singletons. The other parameters were not different. CONCLUSIONS: There is a significant increase in the incidence of gestational diabetes mellitus and disturbance of the 3-hour glucose tolerance test in twin pregnancies. However, insulin requirements were not different, suggesting a mild disturbance of carbohydrate tolerance that was effectively managed by the strategies used to achieve blood glucose control in singletons.     

Committee opinion no. 504: screening and diagnosis of gestational diabetes mellitus

Gestational diabetes mellitus (GDM), defined as carbohydrate intolerance that begins or is first recognized during pregnancy, is associated with increased maternal, fetal, and neonatal risks. The prevalence of GDM in the United States is increasing, probably because of increasing rates of overweight and obesity. A universal recommendation for the ideal approach for screening and diagnosis of GDM remains elusive. At this time, the Committee on Obstetric Practice continues to recommend a two-step approach to screening and diagnosis. All pregnant women should be screened for GDM, whether by patient history, clinical risk factors, or a 50-g, 1-hour glucose challenge test at 24–28 weeks of gestation. The diagnosis of GDM can be made based on the result of the 100-g, 3-hour oral glucose tolerance test, for which there is evidence that treatment improves outcome.     

Early-pregnancy glucose screening for gestational diabetes mellitus

OBJECTIVE: To determine the accuracy of the 50-g, one-hour glucose screening test administered at 16 weeks of pregnancy for identifying women with gestational diabetes mellitus. STUDY DESIGN: Two hundred fifty-five women underwent 50-g, one-hour glucose screening tests at 16 weeks of pregnancy. Those with results > or = 135 mg/dL underwent 100-g, three-hour glucose tolerance tests. All patients without diagnoses of gestational diabetes during the second trimester of pregnancy underwent standard third-trimester glucose testing. RESULTS: Gestational diabetes mellitus was diagnosed in 25 patients. Glucose screening tests administered at 16 weeks of pregnancy identified 96% (24) of these patients. Patients with 16-week glucose screening test results > or = 135 mg/dL had a 55% risk of developing diabetes during pregnancy, while the risk was 0.6% for patients with 16-week test results < or = 110 mg/dL. Patients with 16-week glucose screening test results in the intermediate range, 111-134 mg/dL, had a 4.8% risk of developing diabetes during pregnancy. CONCLUSION: Glucose screening at 16 weeks of pregnancy is a useful alternative to third-trimester screening for gestational diabetes. The negative predictive value of screening test results < or = 110 mg/dL is 99.4%. The positive predictive value for screening test results > or = 135 mg/dL is 55%. This latter finding is superior to the 8.6-22% found during the third-trimester.     

Does insulin secretion in patients with one abnormal glucose tolerance test value mimic gestational diabetes mellitus?

OBJECTIVE: The purpose of this study was to investigate the insulin response to a 3-hour oral glucose tolerance test and to compare the insulin levels in the gestational diabetes mellitus and single abnormal test value groups with a nondiabetic control group. STUDY DESIGN: One hundred ten Turkish women with uncomplicated pregnancy participated in this prospective controlled study between 24 to 28 weeks of gestation. A 100-g 3-hour oral glucose tolerance test was given, and glucose and insulin plasma levels were assayed. The subjects were classified according to established criteria. Early-phase insulin secretion was assessed by the insulinogenic index. Total insulin secretion was assessed by mean insulin level during the oral glucose tolerance test; insulin resistance was assessed by fasting insulin concentration and by the use of the homeostasis model. Data were analyzed by the Student t test and 1-way analysis of variance, with posthoc Bonferroni correction. RESULTS: The fasting insulin levels of patients with normal oral glucose tolerance test results were significantly lower than those of patients with gestational diabetes mellitus and a single value abnormality (P <.001 and P <.005, respectively). The insulinogenic index as a marker of early-phase insulin secretion was significantly lower in gestational diabetes mellitus, compared with that of patients with normal oral glucose tolerance test results (P <.05). The worsening of glycemic profile from normal oral glucose tolerance test results to gestational diabetes mellitus was associated with an increase in the homeostasis model; no significant difference was found between gestational diabetes mellitus and a single value abnormality group in terms of both the homeostasis model and the insulinogenic index. Values for total insulin secretion were highest in gestational diabetes mellitus, followed by the single value abnormality group, both significantly differing from the values of patients with normal oral glucose tolerance test results (P <.001 and P <.005, respectively). CONCLUSION: In this prospective study of Turkish subjects, we found a striking similarity in terms of patient characteristics between the gestational diabetes mellitus group and the single value abnormality group. Additionally, when we used fasting insulin level and insulin resistance as 2 separate criteria of analysis, patients with single value abnormality were indistinguishable from patients with gestational diabetes mellitus; both groups were significantly different from the normal oral glucose tolerance test group. Our findings suggest that a single abnormal test value on an oral glucose tolerance test should be regarded as a pathologic finding and that the patient with a single abnormal test value may be treated similarly to the patient with gestational diabetes mellitus.     

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.     

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.     

Diagnostic of gestational diabetes mellitus and the prevalence of LGA (Large for Gestational Age)

OBJECTIVES: Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance, first time detected in pregnancy. Early diagnosis of the disease may reduce fetal exposure to maternal hyperglycemia and decrease the risk of LGA. The aim of the study was to examine the influence of time and diagnostic method of GDM on the prevalence of LGA and pregnancy outcome among patients with gestational diabetes. MATERIAL AND METHODS: The study was conducted among 211 women with gestational diabetes mellitus, the patients of 1st Clinic of Obstetrics and Gynecology at the Medical University in Warsaw. We have reviewed the results of fasting plasma glucose, 50-g glucose screening test (GCT) and 2 hour 75-g glucose tolerance test in GDM patients with LGA and eutrophic newborns. The t-student or the Mann-Whitney test was used in order to compare both groups. P<0.05 was deemed statistically significant. RESULTS: LGA was diagnosed in 10.4% of patients. We did not find any significant differences in gestational age when GDM was diagnosed, results of fasting glucose GCT and OGTT among LGA (M) and control (K) group. However, when we compared the percentage of LGA in groups of women with different time of GDM diagnosis, the highest prevalence was noted in the group of first trimester diagnosis and between 28 and 32 weeks of pregnancy, which we found interesting. We compared the women and the results of the diagnostic tests with the group of standard time of GDM diagnosis (24-28 week of pregnancy) and the only difference was the late diagnosis. If 75-g glucose tolerance test had not included 1-hour after load glucose assignment, GDM would not have been diagnosed at all in 18.2% of female patients with LGA. We have not found any correlations between the results of the diagnostic tests, the time of the diagnosis or the mode of treatment GDM (diet alone or with insulin) and the birth weight. CONCLUSIONS: 1. Results of fasting glucose and glucose tolerance tests are not useful in the prediction of LGA in GDM pregnancies. 2. Diagnosis of GDM during the recommended period (between 24 and 28 weeks of pregnancy) may decrease the prevalence of LGA (comparing to later diagnostics). 3. 75-g glucose tolerance test should provide fasting, 1 and 2-hour after load glucose assignment.     

The after breakfast 50-g, 1-hour glucose challenge test in urban Mexican pregnant women: its sensitivity and specificity evaluated by three diagnostic criteria for gestational diabetes mellitus

BACKGROUND: To study the sensitivity and specificity of the 50-g, 1-hour gestational glucose challenge test performed 1 to 2 hours after a non-standardized home breakfast in urban Mexican women by using three different gestational diabetes mellitus diagnostic criteria. METHODS: Four hundred and forty-five consecutive women of 24-28 weeks gestation were studied. The glucose challenge test was performed in the fed state and a week later a fasting 100-g, 3-hours oral glucose tolerance test was carried out in all of them. Duplicate serum glucose concentrations were determined by a glucose-oxidase method. Sensitivity and specificity were calculated using three different diagnostic criteria for gestational diabetes mellitus. RESULTS: The glucose challenge test performed as indicated, with a cutoff of 7.8 mmol/L, had 88-89% sensitivity and 85-87% specificity when using as diagnostic criteria those proposed by the National Diabetes Data Group and by Carpenter & Coustan; by using Sacks et al. criteria, the values were 82% and 88%, respectively. Considering only pregnant women > or = 25 years of age, the sensitivity increased to 92% with the National Diabetes Data Group criteria. Pregnant women < 25 years of age had significantly lower blood glucose values than those with age > or = 25 years during the glucose tolerance test. CONCLUSIONS: For the general group the sensitivity of the glucose challenge test performed 1 to 2 hours after breakfast was similar, based on the National Diabetes Data Group and the Carpenter & Coustan's diagnostic criteria for gestational diabetes mellitus. However, when pregnant women > or = 25 years of age were considered, the use of the former criteria yielded a slightly better sensitivity.     

Results of screening tests for gestational diabetes mellitus at Medical University in Warsaw

Our purpose was to determine the incidence of screening for gestational diabetes among the population of women delivering at I and II Departments of the First Faculty of Medical University in Warsaw. A retrospective review of 647 pregnancies was performed. The incidence of gestational diabetes mellitus screening was determined and the rate of occurrence of GDM analyzed. 310 (48%) pregnancies were screened for gestational diabetes mellitus with a 1-hour, 50 gm oral glucose challenge test. 49 (16.07%) of the screens had positive results at a plasma glucose level of > 139 mg/dl. Two-hour 75 gm oral glucose tolerance tests (according to the 1994 World Health Organization panel recommendations) were performed on screen-positive women, eleven of whom (22.45%) were diagnosed with gestational diabetes mellitus. Despite of positive oral 50 gm glucose test, (plasma glucose level 140-179 mg/l) 15 women (30%) haven't had the 75 gm oral glucose test. The incidence of GDM among analyzed population is 4% and when GDM screening is carried out, exceeds 7%. Early gestational glucose screening, if performed, may be beneficial in detecting gestational diabetes. Consideration should be given to fulfill it more frequently and for sure, repeat glucose testing in patients with positive one-hour screening tests.     

Abnormal results on a second testing and risk of gestational diabetes in women with normal baseline glucose levels.

OBJECTIVE: To examine the rate of women with normal initial results to glucose tolerance tests who have abnormal results to subsequent testing, and estimate the risk of gestational diabetes mellitus (GDM) in these women. METHODS: Baseline plasma glucose levels were classified as normal if they were less than 120 mg/dL (group 1) or between 120 and 139 mg/dL (group 2) by the 50-g glucose challenge test (GCT); as abnormal if they were found abnormal by the 50-g GCT but normal by the 100-g glucose tolerance test (OGTT) (group 3); and as abnormal if 1 of the four 100-g OGTT values was abnormal (group 4). A second testing session with the 50-g GCT and 100-g OGTT was performed between the 24th and 28th weeks of pregnancy for 900 women at risk whose initial test results were normal. RESULTS: Of the 823 women with normal baseline results who completed the study, 41.4% had abnormal results to the second 50-g GCT, and gestational diabetes mellitus was diagnosed by the 100-g OGTT in 7.0% of these 823 women. Compared with group 1, the women in groups 2, 3, and 4 were at a significantly increased risk of having an abnormal result to the second 50-g GCT. They were also at a significantly increased risk for GDM. The adjusted odds ratios (ORs) were 3.0 for group 2 (95% confidence interval [CI], 1.2-7.2), 4.9 for group 3 (95% CI, 2.2-11.0), and 11.3 for group 4 (95% CI, 3.9-32.6). CONCLUSION: The risk of developing GDM significantly increased with increasing baseline plasma glucose levels by the 50-g GCT.     

Impaired glucose tolerance associated with adverse pregnancy outcome: a population-based study in southern Sweden

OBJECTIVE: We conducted a population-based study of maternal and neonatal characteristics and delivery complications in relation to the outcome of a 75-g, 2-hour oral glucose tolerance test at 25 to 30 weeks' gestation. STUDY DESIGN: An oral glucose tolerance test was offered to pregnant women in a geographically defined population. Pregnancy outcome was analyzed according to the test result. RESULTS: Among women delivered at Lund Hospital, we identified 4526 women with an oral glucose tolerance value of <7.8 mmol/L (<140 mg/dL), 131 women with a value of 7.8 to 8.9 mmol/L (140-162 mg/dL), and 116 women with gestational diabetes (> or =9.0 mmol/L [> or =162 mg/dL]). A further 28 cases of gestational diabetes were identified, giving a prevalence of 1.2%. An increased rate of cesarean delivery and infant macrosomia was observed in the group with a glucose tolerance value of 7.8 to 8.9 mmol/L (140-162 mg/dL) and in the gestational diabetes group. Advanced maternal age and high body mass index were risk factors for increased oral glucose tolerance values in 12,657 screened women in the area. CONCLUSION: The study stresses the significance of moderately increased oral glucose tolerance values.     

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.     

Correlation between first- and early third-trimester glucose screening test results

One hundred twenty-four normal gravidas had paired first- and early third-trimester (26-32 weeks) 1-hour oral glucose screening tests performed. First-trimester oral glucose screening test values correlated significantly with third-trimester glucose screening test results for the entire population, for whites and non-whites, and for normal-weight and obese patients. First-trimester oral glucose screening test values at or below 110 mg/dL were seldom associated with third-trimester oral glucose screening test results at or above 135 mg/dL and were not associated with abnormal 3-hour glucose tolerance test (GTT) results. Nine of the gravidas (7.3%) were diagnosed with gestational diabetes mellitus during the third trimester, all of whom had first-trimester glucose screening test results above 110 mg/dL. The difference in incidence of gestational diabetes mellitus between gravidas having first-trimester glucose screening test results at or below 110 mg/dL (0%) and those having values above 110 mg/dL (16.4%) was highly significant (P less than .0001). For patients with first-trimester glucose screening test values at or below 110 mg/dL, third-trimester glucose screening may be unnecessary. In contrast, for gravidas having first-trimester glucose screening test results at or above 135 mg/dL, there is a high positive predictive value for elevated repeat glucose screening test results during the early third trimester. Patients having elevated first-trimester glucose screening values at or above 140 mg/dL are at particularly high risk for elevated glucose screening test results later in pregnancy and should forego repeat 1-hour third-trimester glucose screening in favor of a direct third-trimester 3-hour GTT.     

Abnormal glucose screening tests in pregnancy: a risk factor for fetal macrosomia

Of 2276 patients who underwent screening for gestational diabetes mellitus, 1854 (81.5%) had normal glucose screening tests after a 50-g carbohydrate load (serum glucose below 135 mg/dL). Three hundred fifty-seven patients (15.7%) had abnormal glucose screening tests and went on to complete three-hour glucose tolerance tests, of whom 176 (48.7%) were shown to be nondiabetic when further tested using a carbohydrate-loaded, 100-g glucose, three-hour glucose tolerance test. The 176 women with abnormal glucose screens but normal glucose tolerance tests were compared with the 1854 who had normal screening values. The frequency of infants weighing more than 4000 g (greater than 95th percentile at our institution) was 11.9% in the study group and 6.4% in the control group (P = .0086). When the data were corrected for other macrosomia risk factors (advanced age, high parity, obesity, white race, and prolonged gestation), there was still a significantly higher frequency of macrosomia in the study group; this fact suggests that patients with minor abnormalities of carbohydrate metabolism during pregnancy are at risk for delivering a macrosomic infant.     

Capillary blood glucose screening for gestational diabetes: a preliminary investigation

Home glucose monitoring with the use of reflectance meters is an important adjunct in the care of pregnant women with insulin-dependent diabetes. The accuracy of reflectance meters for the assay of capillary glucose specimens has been well documented. The present preliminary study was undertaken to determine the utility of outpatient screening for gestational diabetes mellitus with the use of a reflectance meter (Accu-Chek, Boehringer Mannheim Co.). One hundred twenty-five patients in our high-risk practice had a standard 50 gm glucose load at 26 to 28 weeks' gestation. Capillary glucose values were measured on site with the Accu-Chek. Venous plasma glucose levels were measured by the central laboratory chemistry analyzer. While the laboratory (x) and meter (y) glucose determinations between the two sets of values were highly correlated (R = 0.89, p less than 0.001), there was a significant difference in their average values (x = 111.74, y = 136.35, p less than 0.0001). With the use of a receiver operator characteristic curve, a meter value of 160 mg/dl was determined as the optimal threshold for performing a 3-hour glucose tolerance test. The sensitivity and specificity with the use of a meter value of 160 mg/dl were 93% and 96%, respectively, for detecting an abnormal screening test in venous plasma (greater than or equal to 135 mg/dl). A total of 32 glucose tolerance tests were performed, with four patients included who had venous values less than 135 mg/dl. All eight patients with gestational diabetes mellitus were correctly identified. These data suggest that a glucose reflectance meter can be used for accurate outpatient screening of gestational diabetes mellitus. The potential advantages of capillary blood glucose screening include both cost and efficiency. Patients with abnormal screening values can be promptly identified and scheduled for a follow-up 3-hour glucose tolerance test.     

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.     

Gestational diabetes screening in subsequent pregnancies of previously healthy patients

OBJECTIVE: Our purpose was to evaluate women without gestational diabetes mellitus in an index pregnancy for the likelihood that gestational diabetes would develop and for risk factors for carbohydrate intolerance in a subsequent pregnancy.Study Design: A retrospective review of medical records at a teaching hospital universally screening for gestational diabetes identified multiparous women who had been delivered twice between 1994 and 1997 and who, in the first (index) pregnancy, had had a normal result on a screening test with 50 g of glucose used in a "glucola" beverage (< or =140 mg/dL). RESULTS: In this population with normal glucose screening values in the index pregnancy, 352 (92.4%) of 381 women had at least one risk factor for gestational diabetes. However, none of the 381 women had gestational diabetes in the subsequent pregnancy (0/381, 95% confidence interval < or =1%), including 45 (12. 4%) who had an abnormal result on the 50-g glucose screening test. Regression analysis showed this test result in the index pregnancy (P =.001) to be the only studied variable significantly associated with the 50-g glucose value in the subsequent pregnancy. CONCLUSION: Despite a high rate of risk factors for gestational diabetes, women in our population with a normal glucose value in an index pregnancy have a minimal risk (<1%) that gestational diabetes will develop in a subsequent singleton pregnancy within 4 years. This factor may be included in determining whether women should undergo screening for gestational diabetes.