The significance of one abnormal glucose tolerance test value on adverse outcome in pregnancy

A matched control study of 126 women equally divided into three groups (normal oral glucose tolerance test, one abnormal test value, and gestational diabetes mellitus) was undertaken to examine the relationships among oral glucose tolerance test results, glycemic control in pregnancy, and adverse perinatal outcome. Characterization of metabolic control for the one abnormal oral glucose tolerance test value and the gestational diabetes mellitus groups (before treatment) showed no significant difference. After the start of treatment, however, a significant (p less than 0.01) difference between the groups in level of control was found. While no significant difference in the average birth weight between the three groups was discovered, the incidence of large infants (macrosomia and large for gestational age) was found to be significantly higher in the one abnormal oral glucose tolerance test group when compared with the normal (34% versus 9%; p less than 0.01) and gestational diabetes mellitus group (34% versus 12%; p less than 0.01). No significant difference for the incidence of an infant large for gestational age was found between the normal group and the patients with gestational diabetes mellitus after treatment. Neonatal metabolic disorders were found to be significantly higher for the one abnormal oral glucose tolerance test group (15%) when compared with the control and the gestational diabetes mellitus groups (3%). We conclude that, if left untreated, one abnormal value on an oral glucose tolerance test is strongly associated with adverse perinatal outcome.     

Neonatal morbidity in pregnancy complicated by diabetes mellitus: predictive value of maternal glycemic profiles

The relationship between glycemic control and perinatal outcome was assessed in a relatively uniform population of 75 White Class B through D pregnant diabetic women. All patients used glucose reflectance meter self-monitoring and performed a minimum of four determinations daily. Mean capillary blood glucose was calculated from a minimum of 16 weeks of determinations. Regression analysis confirmed a correlation between these values and third-trimester hemoglobin A1 (p less than 0.001). The study population was divided into two groups on the basis of mean capillary blood glucose values: group I, mean capillary blood glucose less than 110 mg/dl (43 patients) (mean = 96.8 +/- 7.1); group II, mean capillary blood glucose greater than 110 mg/dl (32 patients) (mean = 126 +/- 9.0). Of the 32 patients in group II, eight had mean capillary blood glucose greater than or equal to 130 mg/dl. The degree of maternal glycemic control appeared to affect perinatal outcome. At least one form of infant morbidity was present in 33% of group I infants compared with 53% of group II. Significant differences were observed for the incidence of hypoglycemia (p less than 0.05), macrosomia (p less than 0.05), and respiratory distress syndrome (p less than 0.01). One of six group I infants delivered at 35 to 36 weeks developed respiratory distress syndrome, compared with four of seven group II patients. The appearance of phosphatidylglycerol in amniotic fluid appeared delayed in group II patients at term. These data suggest that maintaining mean capillary blood glucose values less than 110 mg/dl may serve to reduce several major forms of morbidity in the infant of the diabetic mother. This information is helpful in establishing objectives for glycemic control in pregnant women using self-monitoring techniques.     

Diagnosis of gestational diabetes by capillary blood samples and a portable reflectance meter: derivation of threshold values and prospective validation

Paired capillary-venous samples were obtained from 255 women undergoing a glucose challenge test and 116 women undergoing an oral glucose tolerance test. The capillary equivalents for the venous threshold values were calculated by regression analysis. The glucose challenge test predictions of either normal or abnormal agreed in 82%. The sensitivity, specificity, and positive and negative predictive values for the capillary oral glucose tolerance test were 89%, 90%, 62%, and 98%, respectively. These capillary equivalents were then applied prospectively to 147 women undergoing a glucose challenge test and 141 women undergoing an oral glucose tolerance test. The concurrence rate of the glucose challenge test in the prospective group was 90%. The sensitivity, specificity, and positive and negative predictive values for the capillary oral glucose tolerance test were 64%, 95%, 75%, and 92%. When the venous threshold recommendations of the American Diabetes Association were used instead of those standard at our institution, these values increased to 75%, 98%, 83%, and 96%, respectively. The recommended capillary values of the American Diabetes Association were 100% sensitive but had a positive predictive value of only 20%. Based on the prospective group, the cost per case of gestational diabetes identified would decline 63% if both a capillary glucose challenge test and an oral glucose tolerance test were used and 25% if the capillary glucose challenge test and venous oral glucose tolerance test were used. Combining the data set for new regression equations, the following venous-capillary threshold sets emerged: glucose challenge test, 140 mg/dl/150 mg/dl; fasting oral glucose tolerance test, 105 mg/dl/114 mg/dl; 1 hour, 190 mg/dl/211 mg/dl; 2 hours, 165 mg/dl/183 mg/dl; 3 hours, 145 mg/dl/157 mg/dl. The sensitivity, specificity, and negative predictive values for the capillary oral glucose tolerance test with these thresholds were 80%, 97%, 80%, and 97%. In conclusion, capillary glucose testing for diabetes during pregnancy is feasible and cost-effective.     

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.     

Chronic oral terbutaline tocolytic therapy is associated with maternal glucose intolerance

Plasma glucose determinations were performed 1 hour after a 50 gm oral glucose load in 30 patients receiving long-term terbutaline therapy (20 to 40 mg/day for at least 1 week) and 247 normal control patients. A total of 63% of patients receiving terbutaline had an abnormal 1-hour value (greater than or equal to 140 mg/dl), an incidence much higher than that of control subjects (17.8%) (p less than 0.0001) for a relative risk of 3.54 (95% confidence intervals of 2.29 to 5.42). Mean 1-hour values were 112.1 mg/dl for control subjects and 149.8 mg/dl in the terbutaline group (p less than 0.0001). All abnormal values were followed by a 3-hour 100 gm oral glucose tolerance test. A total of 15.9% of the glucose tolerance tests performed in the control group (2.8% overall) were abnormal as opposed to 52.6% (33.1% overall) in patients receiving terbutaline (p less than 0.01). Nine patients were studied before and after terbutaline therapy. Results obtained during administration of terbutaline were significantly higher (102.2 mg/dl before therapy versus 145.2 mg/dl during therapy). We conclude that treatment with oral terbutaline appears to be associated with impairment of glucose tolerance in pregnancy.     

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)     

Glycemic control in gestational diabetes mellitus--how tight is tight enough: small for gestational age versus large for gestational age?

The relationship between optimal levels of glycemic control and perinatal outcome was assessed in a prospective study of 334 gestational diabetic women and 334 subjects matched for control of obesity, race, and parity. All women with gestational diabetes mellitus were instructed in the use of a memory-based reflectance meter. They were treated with the same metabolic goal according to a predetermined protocol. Three groups were identified on the basis of mean blood glucose level throughout pregnancy (low, less than or equal to 86 mg/dl; mid, 87 to 104 mg/dl; and high, greater than or equal to 105 mg/dl). The low group had a significantly higher incidence of small-for-gestational-age infants (20%). In contrast, the incidence of large-for-gestational-age infants was 21-fold higher in the mean blood glucose category than in the low mean blood glucose category (24% vs. 1.4%, p less than 0.0001). An overall incidence of 11% small-for-gestational-age and 12% large-for-gestational-age infants was calculated for the control group. A significantly higher incidence of small-for-gestational-age infants (20% vs. 11%, p less than 0.001) was found between the control and the low category. In the high mean blood glucose category an approximate twofold increase was found in the incidence of large-for-gestational-age infants when compared with the control group (p less than 0.03). No significant difference was found between the control and mean blood glucose categories (87 to 104 mg/dl). Our data suggest that a relationship exists between level of glycemic control and neonatal weight. This information is helpful in targeting the level of glycemic control while optimizing pregnancy outcome in gestational diabetes comparable to the general population.     

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)     

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.     

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.     

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.     

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.     

Effects of ethnicity on glucose tolerance, insulin resistance and beta cell function in 223 women with an abnormal glucose challenge test during pregnancy

This study was conducted to investigate body-mass-index (BMI), insulin resistance and beta cell function in a group of pregnant women. Two hundred and twenty-three consecutive women with an abnormal 50 g glucose challenge test in the third trimester were studied. All underwent oral glucose tolerance testing; 97 had a 100 g test and 126 a 75 g test. Fasting insulin was measured. Insulin resistance and beta cell function were calculated using the homeostasis model. Among the 136 Caucasian, 60 Asian, 11 Indian and 16 Arabic women studied, there were no age differences. Arabic women had higher parity (p < 0.05). Asian women had lower BMI than Caucasian (p < 0.001), Indian (p < 0.01), and Arabic women (p < 0.01). Women with gestational diabetes had higher insulin resistance than women with normal glucose tolerance (2.9+/-4.0 vs. 2.3 +/- 2.5 p = 0.025). Women with gestational diabetes tended to have lower beta cell function 199 +/- 203 vs. 247 +/-380 p = 0.08). Asian women had higher glucose levels than Caucasian women after 50 g challenge (8.9 +/- 2.1 mmol/1 vs. 8.6 +/- 1.6; p = 0.034). Asian women were more likely to have gestational diabetes than Caucasian women (31.7% vs. 14%; p = 0.02). Fasting glucose and insulin were comparable in Asian and Caucasian women. Mean insulin resistance and beta cell function in Asian and Caucasian women were not significantly different. We concluded that Asian women had lower BMI than Caucasian women. Women with gestational diabetes were more insulin resistant. Insulin resistance and beta cell function in Asian and Caucasian women are similar. Gestational diabetes in Asian women is of similar aetiology to that seen in Caucasian women, but occurs at a lower BMI.     

Effect of dietary therapy on pancreatic beta cell function in noninsulin-dependent diabetes mellitus

Twenty-four noninsulin-dependent diabetics, who were newly diagnosed or had discontinued therapy for at least 10 months, were studied for the effect of dietary therapy on pancreatic beta cell function. The mean fasting plasma glucose (176 +/- 14 vs 212 +/- 16 mg/dl, p less than 0.01) and glycosylated hemoglobin (HbA1c, 8.6 +/- 0.5 vs 9.4 +/- 0.6%, p less than 0.001) decreased significantly after 1 month of dietary control, although there was no significant change in mean body weight (57.4 +/- 2.0 vs 57.7 +/- 2.0 kg, p greater than 0.5). The mean incremental serum C-peptide (delta CP) response to oral glucose stimulation (OGTT) increased (4.6 +/- 0.6 vs 3.5 +/- 0.7 ng/ml, p less than 0.01), but that to intravenous glucagon (GT) did not (2.5 +/- 0.2 vs 2.7 +/- 0.2 ng/ml, p greater than 0.1). In 12 patients whose glycemic control improved after dietary treatment, there was a good correlation between the decrement in fasting plasma glucose and the increment in delta CP response to OGTT (r = 0.66, p less than 0.05). In conclusion: after 1 month of dietary therapy in noninsulin-dependent diabetics, (1) the serum C-peptide response to OGTT, but not to GT, improved; (2) the beta cell secretion increased only in those patients with improved glycemic control; (3) there was a good correlation between glycemic control and beta cell function.     

Use of glyburide for the treatment of gestational diabetes: the San Antonio experience.

OBJECTIVES: Equivalent efficacy of glyburide and insulin for treatment of gestational diabetes (GDM) was demonstrated in a recent randomized trial. We describe our experience with glyburide in practice, and suggest factors that predict failure of glyburide treatment. METHODS: Women with GDM treated with glyburide were studied. They were divided into two groups: those who achieved adequate glycemic control with glyburide, and those who did not. The groups were compared in terms of baseline characteristics, including diabetes risk factors and glucose testing values. Receiver operating characteristics (ROC) curves were generated to identify thresholds for fasting plasma glucose and body mass index (BMI) that would predict glyburide failure. RESULTS: Seventy-five women were analyzed: 63 (84%) were successfully treated with glyburide, and 12 (16%) were not. Baseline characteristics were similar between the groups, except that failures had higher 3-h glucose tolerance test (GTT) values at all time points. ROC curves for fasting plasma glucose, pre-pregnancy BMI and BMI at diagnosis revealed no cut-off points for predicting failure of glyburide therapy. However, when fasting plasma glucose value on the GTT was > or = 110 mg/dl, 24% of women failed to respond to glyburide, compared to 12% at < 110 mg/dl (p = 0.15). CONCLUSIONS: In treatment of GDM, glyburide is successful in achieving good glycemic control in most women. Women with high fasting plasma glucose levels, however, may not respond adequately to glyburide therapy.     

Effect of long term use of oral contraceptives on glucose tolerance

The effect of long term use of oral contraceptives on glucose tolerance was studied in 133 women. Oral contraceptives were taken for a period between 3 and 12 years. 25 women without any hormone treatment served as a control group. The intravenous glucose tolerance test (IVGTT) has indicated no pathological decrease of glucose tolerance, measured by k. The glucose tolerance test was performed on all subjects (0.33 Gm. of glucose per kg bodyweight). In one subject we diagnosticated a clinical diabetes. Two patients had a subclinical diabetes. After 10 years of treatment a significant decline was noted in k, also in women with family history of diabetes or a past obstetrics history. Several doubtfully pathological k-values were recorded in women more than 40 years of age. No significant relation could be established between parity and the developement of an abnormal glucose metabolism, while taking the drugs. The effect upon glucose tolerance is not related to the type of oral contraceptive. The evidence is not sufficient to warrant the elimination of oral contraceptives. It is suggested that at least in diabetes suspects, repeated controls of glucose tolerance be carried out during long term cyclic use of oral contraceptives.     

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.     

Is treatment needed for mild impairment of glucose tolerance in pregnancy? A randomized controlled trial

Summary. The study was designed to identify those pregnant women who are diagnosed as having gestational diabetes by National Diabetes Data Group (NDDG) criteria, but normal glucose tolerance (NGT) or impaired glucose tolerance (IGT) by the World Health Organization (WHO) criteria, and to test whether treatment changed the perinatal outcome in those with NGT and IGT. The 216 women with an abnormal 100 g oral glucose tolerance test (OGTT) using NDDG criteria were subjected to a 75 g OGTT. Using the WHO criteria, 111 women (51%) had NGT, 98 (45%) had IGT and 7 (3%) had frank diabetes mellitus. Those with NGT and IGT were randomized into control and treatment groups. The perinatal outcome in these two groups was comparable whether the NGT and IGT groups were analysed together or separately except, that in those who were treated for IGT, smaller babies were born one week earlier than in the control group (3407 g vs 3110g, P<0·01). This suggests that the WHO criteria can safely replace the 100 g OGTT with substantial savings in manpower, money and patients' time.     

Effect of fetal hyperinsulinism on oral glucose tolerance test results in patients with gestational diabetes mellitus

OBJECTIVE: This study was undertaken to evaluate the impact of the fetoplacental glucose steal phenomenon on the results of oral glucose tolerance testing in pregnancies complicated by gestational diabetes mellitus with fetal hyperinsulinism. STUDY DESIGN: This was an analysis of the cases of 34 patients with two consecutive abnormal oral glucose tolerance test results and amniotic fluid insulin measurement before institution of insulin therapy. Patients were divided into groups on the basis of normal versus elevated amniotic fluid insulin concentrations. RESULTS: Oral glucose tolerance tests were done at a mean (+/-SD) of 24.9 +/- 5.7 and 30.7 +/- 3.2 weeks' gestation, and amniotic fluid insulin measurements were done at 31.1 +/- 3.2 weeks' gestation. In 13 women with gestational diabetes mellitus with normal amniotic fluid insulin concentration, maternal postload blood glucose levels at 1 hour increased by 12 mg/dL (168 vs 180 mg/dL; 9.3 vs 10.0 mmol/L; P = .0006) during the course of 6 weeks. In contrast, in 21 women with gestational diabetes mellitus with elevated amniotic fluid insulin levels (>7 microU/mL; >42 pmol/L), 1-hour postload blood glucose levels decreased by 22 mg/dL (201 vs 179 mg/dL; 11.2 vs 9.9 mmol/L; P = .002) during the same period. The higher the amniotic fluid insulin level, the larger the decrease (R = 0.504; P =.02). Although low amniotic fluid insulin levels were correlated significantly with 1-hour glucose levels of the first and second oral glucose tolerance tests, high insulin levels were no longer correlated with the second oral glucose tolerance test. CONCLUSION: Exaggerated fetal glucose siphoning may provide misleading oral glucose tolerance test results in pregnancies complicated by fetal hyperinsulinism by blunting maternal postload glucose peaks. Consequently, oral glucose tolerance test results in a pregnancy complicated by gestational diabetes mellitus with a fetus that already has hyperinsulinemia may erroneously be considered normal.     

Is treatment needed for mild impairment of glucose tolerance in pregnancy? A randomized controlled trial

The study was designed to identify those pregnant women who are diagnosed as having gestational diabetes by National Diabetes Data Group (NDDG) criteria, but normal glucose tolerance (NGT) or impaired glucose tolerance (IGT) by the World Health Organization (WHO) criteria, and to test whether treatment changed the perinatal outcome in those with NGT and IGT. The 216 women with an abnormal 100 g oral glucose tolerance test (OGTT) using NDDG criteria were subjected to a 75 g OGTT. Using the WHO criteria, 111 women (51%) had NGT, 98 (45%) had IGT and 7 (3%) had frank diabetes mellitus. Those with NGT and IGT were randomized into control and treatment groups. The perinatal outcome in these two groups was comparable whether the NGT and IGT groups were analysed together or separately except, that in those who were treated for IGT, smaller babies were born one week earlier than in the control group (3407 g vs 3110 g, P less than 0.01). This suggests that the WHO criteria can safely replace the 100 g OGTT with substantial savings in manpower, money and patients' time.