Carbohydrate intolerance in patients receiving oral tocolytics

This prospective study was designed to evaluate the effects on glucose metabolism of terbutaline used as an oral tocolytic agent. Eighty-six patients were studied when admitted for preterm labor from 24 to 35 weeks' gestation. After intravenous tocolysis, these patients were maintained on 5 mg of terbutaline every 4 or 6 hours. An oral 50 gm, 1-hour glucose challenge test was done 48 hours after terbutaline dosing began. All abnormal glucose challenge test results (greater than or equal to 135 mg/dl) were followed by a standard 100 gm oral glucose tolerance test. Sixty-three percent (54 of 86) of the terbutaline group had an abnormal 1-hour screening result, which was significantly different than the 26.7% (23 of 86) observed in the control group (p less than 0.001). The mean fasting blood sugar and 1-hour postchallenge values were significantly higher in the study than in the control group (p less than 0.0001). Ten of 86 in the treated group (11.6%) and 2 of 86 in the control group (2.3%) with abnormal results met the criteria for gestational diabetes. These numbers achieve statistical significance at p less than 0.05. This study shows a significant effect of oral terbutaline therapy on glucose tolerance during pregnancy. Patients receiving oral terbutaline therapy for suppression of preterm labor should undergo screening for gestational diabetes.     

The effect of oral ritodrine therapy on glucose tolerance in pregnancy

Intravenous ritodrine therapy can cause significant deterioration of maternal glucose homeostasis. We investigated the effect of full maintenance oral ritodrine therapy (120 mg/day) on glucose tolerance in the early third trimester with the use of 50 gm 1-hour screens followed by 100 gm 3-hour oral glucose tolerance tests if the screen level was greater than or equal to 140 mg/dl. Four hundred ninety-one patients were studied, 42 of whom were receiving oral ritodrine therapy. Twenty-one percent of the ritodrine-treated women had an abnormal 1-hour screen, which was not different from the 20% observed in women not receiving therapy. None of the treated group and 13% of the untreated group who had abnormal screens had abnormal oral glucose tolerance tests. The probability of an abnormal test after an abnormal 1-hour screen was also determined.     

Reproducibility of the oral glucose tolerance test in pregnancy

This prospective investigation evaluated the reproducibility of the 100 gm oral glucose tolerance test. Sixty-four obstetric patients with greater than or equal to 135 mg/dl on the 50 gm oral glucose screening test were scheduled for the 100 gm test. All patients repeated the oral glucose tolerance test in 1 to 2 weeks. Both tests included a preparatory diet, and testing conditions were identical. There were no significant differences in the mean test values at each testing interval when the entire study population was considered. Patients were then divided into four groups according to the outcome of the two tests. Forty-eight of 64 (75%) had normal results at each testing period (group 1); 11 of 64 (17%) had initially normal results and abnormal results on retest (group 2); 3 of 64 (5%) had initially abnormal results and normal results on retest (group 3); 2 of 64 (3%) had abnormal results at both testing phases (group 4). There were no significant differences between oral glucose tolerance test results within groups 1 and 4. However, significant differences occurred within groups 2 and 3 between the two tests. Group 2 patients had a greater frequency of an abnormal 1-hour value on the test than group 1 patients (p = 0.001). Overall, the reproducibility of the oral glucose tolerance test was 78% (50 of 64). We recommend the oral glucose tolerance test be repeated when the 1-hour value is abnormal or when the fasting blood sugar, 1-hour, and 2-hour values are near the upper end of the normal range.     

Maternal glucose intolerance and the subcutaneous terbutaline pump.

OBJECTIVE: Our hypothesis was that use of the subcutaneous terbutaline pump does not affect maternal glucose tolerance. STUDY DESIGN: With the 1-hour glucose tolerance test, we examined the incidence of glucose intolerance in 37 patients using the pump compared with that of 54 patients receiving oral terbutaline and 634 control subjects without risk factors for gestational diabetes. The frequency of gestational diabetes and the need for insulin to maintain glycemic control were subjected to chi 2 analysis. RESULTS: The incidence of gestational diabetes was 6% in the control subjects, 5% in patients using the pump (p = 0.8), and 11% in those on the oral therapy regimen (p = 0.4). A total of 8% of controls who had gestational diabetes required both insulin and diet, compared with 100% using the pump (p less than 0.01) and 50% on the oral terbutaline regimen (p = 0.03). CONCLUSION: The incidence of gestational diabetes is not increased in patients receiving terbutaline via the subcutaneous pump. The use of terbutaline by any route significantly increases the need for insulin to achieve glycemic control.     

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.     

Management of women with one abnormal oral glucose tolerance test value reduces adverse outcome in pregnancy

In this study we sought to test the hypothesis that treatment of women with one abnormal oral glucose tolerance test value will result in reduction of adverse outcome. One hundred twenty-six women with one abnormal oral glucose tolerance test value and 146 women in the control group (normal oral glucose tolerance test values) participated in a prospective study during the third trimester of pregnancy. The subjects with one abnormal test result were randomized into treated (group 1) and untreated groups (group II). Group 1 subjects were treated with a strict diabetic protocol to maintain tight glycemic control by means of diet and insulin therapy. Group 2 subjects tested their capillary blood glucose for a baseline period. The study revealed that the level of glycemic control was similar before initiation of therapy (mean capillary blood glucose 118 +/- 14 vs. 119 +/- 15 mg/dl, p = NS) for groups 1 and 2, respectively. There was a significant difference in mean capillary blood glucose (95 +/- 10 vs. 119 +/- 15 mg/dl, p less than 0.0001), preprandial, and postprandial determinations between the treated and untreated groups. The overall incidence of neonatal metabolic complications (4% vs. 14%, p less than 0.05) and large infants (6% vs. 24%, p less than 0.03) was significantly lower in the treated group. Comparison between the control (normal oral glucose tolerance test) and the untreated groups showed a significantly higher incidence of large infants and metabolic complications. No difference was found between the normal and treated groups. Thus we conclude that treatment of individuals with one abnormal oral glucose tolerance test value will result in significant reduction in adverse outcome in pregnancy.     

A double-blind study comparing ritodrine and terbutaline in the treatment of preterm labor

One hundred women in preterm labor were randomly treated with ritodrine or terbutaline in a double-blind fashion. The drugs were comparably effective during intravenous therapy but, in women with intact membranes, an oral dose of terbutaline, 30 mg daily, was significantly more effective than ritodrine, 120 mg daily, in preventing recurrent labor during a 5-day course of oral therapy (one of 19 versus 12 of 23, p less than 0.001). In women with intact membranes, pregnancy was prolonged 40 +/- 25 days (mean +/- SD) in women receiving terbutaline orally and only 22 +/- 24 days in women receiving ritodrine orally (p less than 0.01). In women with intact membranes, a heart rate greater than or equal to 130 bpm occurred in in a higher proportion of women receiving intravenous treatment with ritodrine than among those receiving terbutaline (20 of 31 versus 8 of 27, p less than 0.05). Terbutaline-treated women, however, were significantly more likely to have a serum glucose level in excess of 140 mg/dl than were women treated with ritodrine (13 of 26 versus 6 of 29, p less than 0.05). Side effects commonly observed during intravenous therapy included nausea (22%), chest pain (15%), and shortness of breath (15%). Side effects were significantly (p less than 0.025) more likely to occur during periods when the infusion rate was being increased rather than during periods when the infusion rate was constant.     

Effect of varying degrees of "normal" glucose metabolism on maternal and perinatal outcome

Prior studies concerning effects of varying degrees of normal glucose metabolism on pregnancy have reported an increase in the incidence of a variety of pregnancy complications in women with normal oral glucose tolerance test results as the glucose concentration after a standardized meal rose. However, these investigations have neglected to include a control group of women with gestational diabetes for comparison. We theorized that if the adverse outcomes noted were indeed a reflection of glucose concentration, women with gestational diabetes should have an even higher incidence of these complications. Mother and infant charts of 312 consecutive women undergoing an oral glucose tolerance test were reviewed. A glucose challenge test preceded the oral glucose tolerance test in 310. The glucose challenge test value was less than 140 mg/dl in 64 and greater than or equal to 140 mg/dl in 246. There were 63 abnormal oral glucose tolerance test results (2.7% of the population studied). Among all patients, the relationship between glucose challenge test and oral glucose tolerance test values followed a gradient with a progressive rise in mean oral glucose tolerance test values when the glucose challenge test result was greater than or equal to 160 mg/dl. However, the incidence of an abnormal oral glucose tolerance test result did not rise significantly until the glucose challenge test result exceeded 180 mg/dl. A wide variety of outcome parameters were studied; none were related to the glucose challenge test value. Similar analysis of the 2-hour oral glucose tolerance test value revealed an increase in the incidence of nonelective operative deliveries and a decrease in the percentage of infants discharged home with their mother where values were greater than 180 mg/dl. However, when women with gestational diabetes were excluded from analysis, neither the glucose challenge test nor the 2-hour glucose tolerance test measurements were related to adverse outcome. When analysis was limited to women with gestational diabetes, there was no clinically significant relationship between either glucose challenge test or 2-hour glucose tolerance test and the outcome parameters. Finally, when analysis was repeated according to diagnosis, women with gestational diabetes had a significantly higher risk of having nonelective operative delivery, premature delivery, growth-retarded neonate, 1-minute Apgar score less than 7, and neonatal hypoglycemia than women with normal oral glucose tolerance test results.(ABSTRACT TRUNCATED AT 400 WORDS)     

Randomized trial of diet versus diet plus cardiovascular conditioning on glucose levels in gestational diabetes

We studied the impact of a training program on glucose tolerance in gestational diabetes mellitus. Women with gestational diabetes mellitus (N = 19) were randomized into either group I, a 6-week diet alone group (24 to 30 kcal/kg/24 hours; 20% protein, 40% carbohydrate, 40% fat), or group II, which followed the same diet plus exercise (20 minutes three times a week for 6 weeks). An arm ergometer was used to maintain heart rate in the training range. Glycemic response was monitored by glycosylated hemoglobin, a 50 gm oral glucose challenge with a fasting and 1-hour plasma glucose, and blood glucose self-monitoring, fasting and 1 hour after meals. Week 1 glycemic parameters were the same for both groups. Week 6 data (mean +/- SD) were as follows: group I glycosylated hemoglobin, 4.7% + 0.2% versus group II, 4.2% +/- 0.2%; p less than 0.001. The group I glucose challenge fasting value was 87.6 +/- 6.2 versus 70.1 +/- 6.6 mg/dl, p less than 0.001 for group II. The group I 1-hour plasma glucose challenge result was 187.5 +/- 12.9 mg/dl versus 105.9 +/- 18.9 mg/dl for group II, p less than 0.001. The glycemic levels diverged between the groups at week 4. We conclude that arm ergometer training is feasible in women with gestational diabetes mellitus and results in lower glycosylated hemoglobin, fasting, and 1-hour plasma glucose concentrations than diet alone. Arm ergometer training may provide a useful treatment option for women with gestational diabetes mellitus and may obviate insulin treatment.     

Postpartum testing for antecedent gestational diabetes

Gestational diabetes is a predictor of glucose intolerance in subsequent pregnancies and in the nongravid state. Many pregnant women are not tested for gestational diabetes, although they or their offspring may show signs suggestive of antecedent hyperglycemia. We examined the diagnostic utility of a postpartum (within 48 hours), 100 gm, oral glucose tolerance test and cord plasma glucose, cord plasma C-peptide, and 2-hour neonatal plasma glucose tests to detect antecedent gestational diabetes in women with documented gestational diabetes (n = 37) or with normal glucose tolerance test results late in the third trimester (n = 28). The 1-hour, 2-hour, and incremental 1-hour + 2-hour [( 1-hour - fasting] + [2-hour - fasting]) [2-hour - fasting]) glucose values of the postpartum glucose tolerance test showed significant differences between study participants with and without gestational diabetes (164 +/- 30 versus 115 +/- 22, 145 +/- 31 versus 101 +/- 21, and 153 +/- 51 versus 67 +/- 33 mg/dl, respectively, p less than 0.025). Maternal fasting and 3-hour postpartum glucose tolerance test glucose, cord plasma glucose, cord plasma C-peptide, and 2-hour neonatal plasma glucose values showed no significant between-group differences. Receiver operating characteristic curve analyses for these tests indicated that the incremental 1-hour + 2-hour postpartum glucose tolerance test glucose values best sustain test specificity at the low test threshold values necessary for high test sensitivity. A threshold of 110 mg/dl for this test yielded a predicted specificity of 90% and sensitivity of 80% with regard to antecedent gestational diabetes.     

First prenatal visit glucose screening

In order to determine the benefit of glucose screening at different stages of pregnancy, a prospective study of 999 patients was performed. All the patients underwent a nonfasting glucose screen at their first prenatal visit. This screen consisted of an oral 50 gm glucose load followed by a 1 hour serum glucose determination. If the glucose result was 130 mg/dl or higher, a 3-hour oral glucose tolerance test was performed at that time. There were 228, 354, 122, and 295 patients with gestational ages less than 14 weeks, 14 to 23 weeks, 24 to 28 weeks, and more than 28 weeks, respectively. The group less than 24 years of age had a significantly lower mean screening glucose value (106.1 +/- 35.9 mg/dl) than the group whose age was 24 years or older (117.4 +/- 35.9 mg/dl). There were significantly fewer patients with elevated screening glucose values when the patients were less than 24 years of age. Nevertheless, in the final analysis, 13% of the gestational diabetics diagnosed were in the age group younger than 24 years. Although the majority of the diagnosed gestational diabetic had elevated screening glucose values after 23 weeks of gestation, 33% had positive screening tests before 24 weeks. Earlier glucose screening, regardless of maternal age or gestational age, can lead to an earlier diagnosis of gestational diabetes. Cost of universal screening, regardless of maternal age, is only slightly more expensive than a screening protocol with a minimum age limit.     

Clinical usefulness of estimation of serum fructosamine concentration as screening test for gestational diabetes

Serum fructosamine levels and fructosamine/protein ratios were measured in 100 pregnant women who underwent glucose tolerance tests because of clinical risk. Compared with normal pregnant women, the 13 study participants with gestational diabetes had higher fructosamine/protein levels (39 +/- 3.9 mumol/gm versus 37 +/- 3.2 mumol/gm, p less than 0.05), fasting serum glucose levels (107 +/- 13.7 mg/dl versus 82 +/- 8.6 mg/dl, p less than 0.001), and area under curve of glucose tolerance test (36 +/- 5 gm x min x dl-1 versus 22 +/- 3.6 gm x min x dl-1, p less than 0.001). The serum fructosamine levels were not significantly different between the two groups of participants (2.3 +/- 0.26 mmol/L versus 2.2 +/- 0.17 mmol/L); 10 of the 13 women with diabetes had a fructosamine/protein ratio within 2 SD of the mean of the groups of normal pregnant women. Spontaneous caloric intakes (r = 0.72, p less than 0.005) and the hospital mean daily capillary glucose levels during diabetic diet (r = 0.72, p less than 0.005) correlated better with the fructosamine/protein ratio than with fasting serum glucose levels (r = 0.58, p less than 0.05) and area under curve (r = 0.57, p less than 0.05). Consequently, serum fructosamine and fructosamine/protein ratio levels should be considered insensitive as a screening test in pregnant patients with clinical risk of gestational diabetes.     

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.     

Gestational diabetes: impact of home glucose monitoring on neonatal birth weight

Two groups of 58 gestational diabetic women matched for age, prepregnancy weight, height, and parity were studied. The home glucose monitoring study group performed fasting and 1-hour postprandial capillary blood glucose testing after every meal. The control group was followed by conventional treatment. The incidence of macrosomia (birth weight of greater than or equal to 4000 gm) and large (greater than or equal to 90%) for gestational age infants was significantly reduced in the home glucose monitoring group. The mean birth weight of the study group was 3231 +/- 561 gm, while that of the control group was 3597 +/- 721 gm (p less than 0.002). Significantly more patients in the home glucose monitoring group were receiving insulin therapy (50% versus 21%). We believe that intensive home glucose monitoring will allow for the early identification of those gestational diabetic patients needing insulin and thus reduce the incidence of macrosomia and large for gestational age infants.     

Studies on glucose challenge test (GCT) as a screening procedure for gestational diabetes mellitus

A glucose challenge test (GCT) was developed as a screening procedure for the diagnosis of gestational diabetes mellitus (GDM). The method includes a 50gm oral glucose load and measurement of the plasma glucose concentration once at one hour after ingestion. The data were examined in 1,184 pregnant women seen at the outpatient clinic of our department from May 1984 to December 1986. Prior to the present study, 722 pregnant women were given a 75gm glucose tolerance test (75gGTT) and plasma glucose and IRI values were also analyzed. 1) Because glucose tolerance evaluated by the GCT was revealed to be impaired around the 28th week of pregnancy, it seems appropriate that screening for GDM should be planned during this period whenever possible. 2) The mean values obtained with GCTs performed before and after 28 weeks were 119 +/- 25mg/dl and 128 +/- 25mg/dl, respectively. 3) When the one-hour plasma glucose levels were compared after one 50 and one 75gm glucose load at intervals of less than 2 weeks, there was reproducibility in individual women with normal glucose tolerance, while the results were consistent in patients with DM or GDM. A mean difference of 18mg/dl at one hour was shown between the different glucose loads. 4) When screening for GDM was attempted in pregnant women with the 75gGTT, sensitivity and specificity were highest in the plasma glucose level at the one hour point. 5) GDM was found in the group of patients with plasma glucose levels of 155mg/dl or higher determined by GCT; the incidence was high in patients with plasma glucose levels of 160mg/dl or higher.(ABSTRACT TRUNCATED AT 250 WORDS)     

Should the fifty-gram, one-hour plasma glucose screening test for gestational diabetes be administered in the fasting or fed state?

To determine whether the 50 gm, 1-hour plasma glucose screening test for gestational diabetes should be administered in the fasted or fed state, 50 presumed normal and 20 gestational diabetic pregnant women in the early third trimester underwent this test twice, once under each condition, within a 1-week interval. There was no difference in test results under the two conditions among the normal individuals (fasted 118.4 +/- 24.7 mg/dl; fed 115.8 +/- 23.4 mg/dl). However, when the test was administered to women with known gestational diabetes, the result was significantly (p = 0.011) higher if patients were fasted (173.9 +/- 28.8 mg/dl) than if they had been given a standard 600 kcal meal 1 hour previously (154.8 +/- 24.1 mg/dl). The effect of these two conditions on the sensitivity and specificity of the screening test is described, and it is suggested that the threshold for glucose tolerance testing be 130 mg/dl if the test is administered in the fed state.     

Screening for carbohydrate intolerance in pregnancy: a comparison of two tests and reassessment of a common approach

The usefulness of glycosylated hemoglobin as a prenatal screening test for carbohydrate intolerance was studied in 806 consecutive subjects by correlating glycosylated hemoglobin to 1-hour post-50 gm Glucola plasma glucose levels, 3-hour oral glucose tolerance tests, and perinatal and maternal outcomes. Sixty-seven subjects whose 1-hour post-50 gm Glucola plasma glucose levels were greater than or equal to 150 mg/100 ml underwent 3-hour oral glucose tolerance tests; 12 were diagnostic of carbohydrate intolerance. Compared to carbohydrate-tolerant control subjects, gravid patients with carbohydrate intolerance were older, more obese, had higher 1-hour post-50 gm Glucola plasma glucose and glycosylated hemoglobin levels, and infants with increased birth weight percentiles, depressed 5-minute Apgar scores, and an increased incidence of shoulder dystocia and perinatal mortality. Three of 10 carbohydrate-intolerant patients who were evaluated post partum were found to have previously undiagnosed diabetes. Division of measurements of 1-hour post-50 gm Glucola plasma glucose and glycosylated hemoglobin into normal, borderline, and suspicious groups demonstrated a reduction in discriminatory capability of glycosylated hemoglobin as compared to the 1-hour post-50 gm Glucola plasma glucose. We conclude that laboratory screening for carbohydrate intolerance should be a standard element of the prenatal evaluation; gravid patients found to have carbohydrate intolerance should be reevaluated post partum to rule out overt diabetes, and the 1-hour post-50 gm Glucola plasma glucose test is the preferred means of routine screening for carbohydrate intolerance in pregnancy.     

Screening for gestational diabetes: one-hour carbohydrate tolerance test performed by a virtually tasteless polymer of glucose

Although the 1-hour 50 gm blood glucose screening test is an effective way of detecting diabetes in pregnancy, the taste of available glucose drinks often creates gastrointestinal symptoms and leads to refusal of the patient to be tested. The efficacy of a virtually tasteless glucose polymer in testing carbohydrate tolerance in pregnancy was determined. Sixty-one pregnant patients undergoing screening for gestational diabetes underwent a 1-hour carbohydrate tolerance test of both glucose and a glucose polymer within 3 days of each other. Analysis of the data revealed a high degree of agreement between the results of the 1-hour carbohydrate tolerance test (kappa = 0.62, p less than 0.0001). These data suggest that glucose polymer can be used effectively in screening for gestational diabetes.     

Prenatal screening for gestational diabetes throughout office hours

A group of 1666 consecutive pregnant women attending our prenatal clinic was screened for gestational diabetes (GD). Patients with risk factors (155) underwent a classical 50 g OGTT, while 1511 patients without risk factors for GD were submitted at random throughout the day to a simplified OGTT, consisting of a single blood glucose determination 1 h after the glucose ingestion. In these patients, plasma glucose 1 h after the glucose load averaged 104 +/- 1 mg/dl and exceeded 135 mg/dl in 315 patients. In the latter group, retested with a standard 50 g OGTT, 48 out of 1511 patients (3.2%) finally met the criteria for GD, while 25 patients had an abnormal OGTT in the group with risk factors. The blood glucose levels after simplified 50 g glucose load were significantly higher in the third (vs. first) trimester of pregnancy (113 +/- 1 vs. 96 +/- 1 mg/dl, p less than 0.001). A significant increase in mean glucose concentrations was also observed for those patients tested after 11 a.m. (107 +/- 1 mg/dl vs. 99 +/- 1 mg/dl prior to 11 a.m. p less than 0.001) and for the women with an ideal body weight (IBW) greater than or equal to 150% at the beginning of pregnancy (124 +/- 7 mg/dl vs. 104 +/- 1 mg/dl for less than 150% IBW, p less than 0.001). These variations in glucose tolerance, related to the time of the day, the gestational age and the body weight, are of limited amplitude and should not be considered in the determination of the cut-off point of the screening test. Glucose loading at random throughout the day is a simple and useful tool for the routine detection of unsuspected GD in pregnant patients attending prenatal clinics.     

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.