New criteria for interpretation of the 75 g oral glucose tolerance test in pregnancy

A 75 g oral glucose tolerance test (OGTT) was performed on 135 high-risk pregnant patients. When the current World Health Organization (WHO) criteria for the diagnosis of gestational-glucose tolerance were applied, 88 patients were considered normal, 11 had gestational diabetes, and 36 patients had impaired-glucose tolerance, respectively. The plasma glucose, insulin, and C-peptide levels during the OGTT were further studied in the 88 patients (who had normal results). Two metabolically distinct groups were identified; a group (n = 53) with a 2-hour plasma glucose less than or equal to 6.6 mmol/L (118.8 mg/dL), had a normal insulin and C-peptide pattern, and a second group (n = 35) who had 2-hour plasma glucose greater than 6.6 mmol/L displayed a glycemic, insulin, and C-peptide pattern similar to that of patients with gestational diabetes mellitus. The risks of macrosomic babies and operative delivery were significantly greater in the latter group. These results suggest that in our pregnant population, a group of patients with impaired glucose tolerance will be under-diagnosed using the current WHO criteria. Based on our results new criteria for gestational glucose intolerance are suggested for our population.     

Outcome of glucose tolerance condition in patients with normal glucose tolerance with either persistently high or low 1-h postchallenge glucose levels in 75 g oral glucose tolerance test

International Journal of Diabetes in Developing Countries - This study aimed to investigate whether persistently high 1-h postchallenge glucose (PG) levels in a 75 g oral glucose tolerance...     

Glucose levels and insulin secretion during a 75 g glucose challenge test in normal pregnancy

Objectives. The aim of the study was to evaluate glucose levels and insulin secretion early in pregnancy and at a time when gestational diabetes mellitus frequently occurs in order to define reference values for glucose tolerance during pregnancy. The results were also related to maternal factors that might identify subjects at risk of developing gestational diabetes mellitus as well as foetal factors that might be a result of impaired glucose tolerance during pregnancy. Design. A prospective study. Setting. All Caucasian women attending one antenatal out-patient care unit were offered a 75 g oral glucose tolerance test at the 17th and 32nd week of gestation. Subjects. A total of 586 consecutive pregnant women were included in the study. All 586 women were examined by repeated blood glucose measurements and 298 agreed to perform oral glucose tolerance tests as well. Main outcome measures. Venous whole blood glucose values were measured in the fasting state and in samples obtained 15, 30, 45, 60, 75, 90 and 120 min after oral intake of 75 g glucose. Serum insulin and C-peptide were also measured at these times. In all subjects, a random blood glucose sample was taken at the first visit, and thereafter at the 20th, 30th and 36th week of gestation. Information was also obtained from all subjects regarding body mass index, weight gain during pregnancy, smoking habits, family history of diabetes and hypertension, hypertension during pregnancy, past obstetric history, parity, and fetal outcome. Results. The glucose tolerance was significantly impaired at the 32nd week of gestation compared with the 17th week of gestation. The mean +2SD 2h glucose value during the oral glucose tolerance test at the 32nd week of gestation was 8.0 mmol L^?1. Impaired glucose tolerance was characterised by increased insulin resistance, with a significant rise in serum insulin and C-peptide concentrations and in the insulin/glucose index during the oral glucose tolerance test at the 32nd week of gestation. Maternal factors associated with an impaired glucose tolerance were a family history of diabetes mellitus, smoking, a weight gain more than 18 kg during pregnancy, and glucosuria, while a family history of hypertension and hypertension present during pregnancy were not. Foetal factors that might be a result of impaired glucose tolerance during pregnancy, e.g. macrosomia and prematurity as well as complicated deliveries such as vacuum extraction/forceps or Caesarean section, all tended to be associated with higher blood glucose values. The same pattern was seen when the Apgar score was <7. Conclusions. The results from this study show that the present cut-off values for diagnosis of gestational diabetes mellitus should be revised. Even if some maternal factors might indicate an increased risk for impaired glucose tolerance during pregnancy, they are probably not enough to detect women with gestational diabetes mellitus. Therefore, a screening programme for gestational diabetes should be considered.     

Association between smoking and post-load plasma glucose levels using a 75-g oral glucose tolerance test: The Saku Study

Current smoking was associated with low insulin secretion and high 30-min plasma glucose (PG), 60-min PG, and area under the curve of PG, whereas current smoking was not associated with fasting PG and 2-h PG levels in both individuals with normoglycemia and individuals with pre-diabetes in a large-scale community-based study.     

Assessing 1-h plasma glucose and shape of the glucose curve during oral glucose tolerance test

OBJECTIVE: To assess the cutoff values at different time points for impaired glucose regulation (IGR) and diabetes, the glucose curve and isolated 1-h hyperglycemia were monitored during an oral glucose tolerance test (OGTT). METHODS: Two thousand eight hundred and eighty-six subjects (1300 men and 1586 women) were recruited to have an OGTT. Plasma was collected at 0, 30, 60, 120, and 180 min to analyze glucose and insulin. The diagnosis of impaired fasting glucose, impaired glucose tolerance, and diabetes was based on World Health Organization and American Diabetes Association's criteria. Those with fasting plasma glucose (FPG) < 5.6 and 2-h plasma glucose (PG) < 7.8, but 1-h PG > or = 7.8 and < 11.1 mmol/l were defined as 1h-High7.8, and those with FPG < 7.0 and 2-h PG < 11.1, but 1-h PG > or =11.1 mmol/l as 1h-High11.1. The cutoff values were calculated by receiver operating characteristic (ROC) curve. The correlation between beta-cell function and the area under the curve of glucose (AUCg) and the shape index was analyzed with linear regression. RESULTS: The cutoff values for IGR were 5.6, 9.7, 10.1, 7.8 and 6.1 mmol/l for blood glucose at 0, 30, 60, 120 and 180 min, 24 for AUCg and 1.3 mmol/l for the shape index. The cutoff values for diabetes were 6.8, 11.2, 13, 11.1 and 7 mmol/l for 0, 30, 60, 120 and 180 min, 30.9 for AUCg and 2 mmol/l for the shape index. Both AUCg and the shape index were inversely related to beta-cell function. The profiles of glucose and insulin in the subgroup with isolated 1-h hyperglycemia were very different from those seen in subjects with normal glucose tolerance or IGR. CONCLUSIONS: The present study provides new information on measures other than the fasting and 2-h PG to evaluate glucose metabolism in vivo and stimulates further research aimed at assessing the value of the OGTT 1-h PG concentration prospectively.     

Correlation between fasting plasma glucose and two-hour plasma glucose during oral glucose tolerance test in South Indians

The diagnostic criteria for diabetes have been recently revised and the fasting plasma glucose (FPG) level reduced to 126 mg/dL, since the earlier cutoff of 140 mg/dL was considered to correspond to a much higher level than the 2-hour postglucose (2 h PG) value of 200 mg/dL. However, there are few data directly correlating FPG and 2 h PG during an oral glucose tolerance test (OGTT). This study reports on a retrospective analysis of 5,936 OGTTs performed at a diabetes center in South India and attempts to correlate the FPG and 2 h PG values. Using a 2 h PG of 200 mg/dL or higher as the diagnostic criterion, 46.7% of the cohort had diabetes. The corresponding values using the old FPG of 140 mg/dL or higher and the new FPG of 126 mg/dL or higher were 31.7% and 39.8%, respectively. If the FPG was further reduced to 118 mg/dL, the "diabetic yield" increased to 45.8%, ie, it approached the figures based on a 2 h PG of > or =200 mg/dL. Various regression equations were used to correlate FPG and 2 h PG values. When FPG was used as the dependent variable, the semilogarithmic regression equation provided the best fit, and using this model, the 2 h PG of 200 mg/dL corresponds to a FPG of 118 mg/dL. When the 2 h PG was used as the dependent variable, the log-log model provided the best fit, and using this model, a 2 h PG of 200 mg/dL corresponds to a FPG of 118 mg/dL. Thus, a FPG of 118 mg/dL seems to correlate with a 2 h PG of 200 mg/dL in South Indians.     

Meaning of upper limit of normal range of post‐load 1‐h plasma glucose level defined by oral glucose tolerance test in Japanese subjects

Aims/Introduction

To identify upper limit post‐load 1‐h plasma glucose (1‐h PG) after 75‐g oral glucose test in a Japanese population.

Materials and Methods

A total of 918 subjects were enrolled. We divided the subjects into two groups: normal 2‐h post‐load plasma glucose (2‐h PG; <140 mg/dL) and impaired 2‐h PG group (≥140 mg/dL).

Results

A total of 417 subjects had normal 2‐h PG and 501 had impaired 2‐h PG. The receiver operating characteristic (ROC) curve showed that the optimal cut‐off value of 1‐h PG was 179 mg/dL (area under ROC curve = 0.89), providing that the sensitivity, specificity, and positive and negative predictive value were 85, 79, 82 and 83%, respectively. The subjects with 1‐h PG < 179 mg/dL consisted of 0.5% diabetes and 99.5% non‐diabetes, whereas those with 1‐h PG ≥ 179 mg/dL consisted of 26.9% diabetes and 73.1% non‐diabetes (P < 0.01). Furthermore, there was a significant correlation between 1‐h PG and 2‐h PG (r² = 0.57, P < 0.01).

Conclusions

These data suggested that 179 mg/dL is the upper limit of the normal range of post‐load of 1‐h PG in a Japanese population. Thus, the subjects with 1‐h PG ≥ 179 mg/dL might be at risk of developing future diabetes. Therefore, appropriate prospective study should be carried out to test this hypothesis.     

Significant thresholds for the 75-g oral glucose tolerance test in pregnancy

The significant threshold values for the 75-g oral glucose tolerance test (oGTT) during pregnancy have yet to be conclusively determined. This study aimed to identify the risk significance of various set thresholds for the oGTT result. Women undergoing a 75-g oGTT during the third trimester of pregnancy were classified into three groups: mild gestational impaired glucose tolerance (GIGT; 2-h postload glucose, 8.0–8.5 mmol/l; n=75), moderate-severe GIGT (8.6–10.9 mmol/l; n=167), and GDM (≥11.0 mmol/l; n=76). Outcome indicators of these three groups of women were compared to the parameters of the women with a presumed normal carbohydrate metabolism (n=12,185). The results show that with increasing oGTT thresholds, there was an increasing risk of maternal morbidity in the form of hypertensive disorders complicating pregnancy, as well as obstetric intervention such as induction of labor, cesarean delivery, and preterm delivery. The infant was also at increasing risk with increasing oGTT thresholds from respiratory distress, macrosomia, and associated shoulder dystocia. It would appear, therefore, that abnormal glucose tolerance in pregnancy, even as defined by the World Health Organization criteria, has proportionate risks to both mother and child.     

Blood sugar level and immunoreactive insulin in the blood plasma in pregnant women with supposed prediabetes in the dynamics of a normal glucose tolerance test]

A study was made of the blood sugar level and blood plasma immunoreactive insulin (IRI) on fasting stomach and in the GTT dynamics in 33 pregnant women with a possible prediabetes and also in 8 nonpregnant women and 20 pregnant women of the control group. GTT proved to be normal in all the women under study. There proved to be no significant difference between the blood sugar level on fasting stomach and in the GTT dynamics in pregnant women of both groups and in the nonpregnant women. In comparison with nonpregnant women, pregnant women of both groups displayed a higher mean blood sugar elevation during the whole GTT period--in the II and III trimesters. Blood plasma IRI in the pregnant women with a possible prediabetes and in the pregnant women of the control group on fasting stomach and in the GTT dynamics showed no significant difference between one another. In comparison with nonpregnant women, pregnant women of both groups showed an increase in IRI content of fasting stomach and in the GTT dynamics beginning from the II trimester and reaching the maximal level during the III trimester of pregnancy. IRI over glucose index did not differ in pregnant women of both groups from the nonpregnant women. Thus it was revealed that hyperinsulinemia in pregnancy in practically healthy women and in women with a possible prediabetes was compensatory in character.     

Changes in plasma amino acids during the oral glucose tolerance test in hepatic diseases

We have measured the plasma concentration of neutral amino acids before and after an oral glucose tolerance test (100 g) in patients with liver cirrhosis (LC), chronic active hepatitis (CAH), chronic persistent hepatitis (CPH), acute hepatitis in the acute stage (AHa) and acute hepatitis in the convalescent stage (AHc) and normal controls. The ratio of the concentration of an amino acid to the sum of those of the other neutral amino acids that compete during transport through the blood brain barrier (BBB), which was reported to correlate well with the brain level of the amino acid, was compared in patients with various liver diseases. The ratios of Trp (Trp/Tyr + Phe + Ile + Leu + Val), Tyr, Phe, and Val increased after glucose loading in all subjects, except Tyr in normal controls, which slightly decreased. On the other hand, Ile and Leu ratios decreased (Trp; tryptophan, Tyr; tyrosine, Phe; phenylalanine, Ile; isoleucine, Leu; leucine, Val; valine). LC showed a characteristic pattern; the ratios of Trp and Tyr were highest among all diseases at 3 hours after glucose loading, and those of Ile, Leu and Val were lowest. We assumed that delta an amino acid ratio = the amino acid ratio at 3 hrs after glucose loading minus the amino acid ratio at 0 hr. In LC, delta Trp ratio and delta Tyr ratio were highest, while delta Val ratio was lowest. The delta Phe ratios in AHa and AHc were significantly higher than those in healthy controls. From these results, the uptake of Trp and Tyr might be supposed to be highest and that of Val was lowest in LC, after glucose loading.     

Plasma glucagon suppressibility after oral glucose in obese subjects with normal and impaired glucose tolerance

Blood glucose, plasma insulin, and glucagon responses after a 75 g oral glucose-tolerance test were assessed in 9 normal controls, 5 obese nondiabetics (ON), 5 obese nondiabetics with fasting hyperinsulinemia (obese “resistant” nondiabetics—OR), 9 obese with impaired glucose tolerance (O-IGT), and 9 nonobese insulin-dependent diabetics (IDD). Fasting plasma glucagon concentrations were significantly higher in all groups of patients in comparison to the normal controls. Insulin secretion, evaluated in all but the IDD, was similar to normal in the ON and increased in the OR and O-IGT. Normal glucagon suppression was observed in the lean controls and ON but not in OR, O-IGT, and IDD. We suggested that the resistance to glucagon suppression after glucose load in the OR and O-IGT in the presence of increased insulin response could be an indication that the A cell participates in the relative insulin insensitivity of these subjects.     

Comparison of oral glucose tolerance test (OGTT) 100 g with OGTT 75 g for evaluation of acromegalic patients and the impact of gender on test reproducibility

Context Growth hormone (GH) measurements during an oral glucose tolerance test (OGTT) are essential for the diagnosis and follow‐up management of acromegaly. However, both 100 g glucose (OGTT₁₀₀) and 75 g glucose (OGTT₇₅) test variants are in clinical use. Whether the tests are interchangeable concerning GH nadir and test interpretation is unclear. Furthermore, information on test reproducibility and the impact of gender is scarce. Objective To compare both tests in acromegalic patients and to evaluate test reproducibility with respect to gender. Design, subjects and methods OGTT₁₀₀ and OGTT₇₅ were performed on two consecutive days in 54 acromegalic patients (46·9 ± 1·8 years, 30 women). OGTT₇₅ was repeated on three different occasions in 11 healthy men and 13 healthy women at different phases of the menstrual cycle. Results GH nadirs were comparable between tests [2·40 ± 0·52 (OGTT₁₀₀) and 2·46 ± 0·54 μg/l (OGTT₇₅); P = 0·356]. There were no differences at any time point in the mean values of GH, serum glucose or insulin between the two test variants. Test interpretation was highly consistent between the OGTT₁₀₀ and OGTT₇₅ [area under the receiver operated curve (ROC) = 0·995]. In men, GH, insulin and glucose measurements during OGTT₇₅ were highly reproducible. In women, however, basal and GH nadirs were significantly higher midcycle (P < 0·05). Conclusions In acromegalic patients, there is no difference in GH nadirs and test interpretation after the ingestion of 100 g or 75 g glucose. The OGTT₇₅ is highly reproducible in men, but in women, it should be performed preferably in the early follicular phase.     

正常糖耐量者口服葡萄糖-胰岛素释放试验的胰岛素分泌曲线特点的研究

目的研究口服葡萄糖一胰岛素释放试验（OGIRT）的胰岛素（Ins）分泌曲线特点,初步探讨适用于I临床评价个体胰岛素敏感性和8细胞分泌功能的方法。方法对12例正常糖耐量者行OGIRT和静脉糖耐量试验（IVGTT）,观察OGIRT、IVGTT血浆Ins分泌峰值时间分布频数,分析胰岛素敏感性和B细胞功能各指标相关指数。结果OGIRT血浆Ins分泌高峰出现于35-45min,无明显第二分泌峰。经多因素线性回归分析表明20、30、35minIns增值与葡萄糖增值的比值（ΔI20／ΔG20、ΔI30／ΔG30、ΔI35／ΔG35）与第一相（1PH）胰岛素分泌、葡萄糖及胰岛素曲线下面积比值（SGI）、胰岛素作用指数（IAI）、HOMA—IR、胰岛素分泌指数均不相关（P〉0．05）,ΔI40／ΔG40与SGI、IAI、HOMA-IR显著相关（P均〈0．01）。结论OGIRT可能不能反映1PH;OGIRTΔI40／ΔG40比I20／ΔG20、△I30／ΔG30能更好地评估β细胞功能。     

Discrepancy between IGF-1 and GH during 75 g oral glucose tolerance test measures to acromegaly screening in a patient with macroprolactinoma--case report and literature review

We describe a patient with macroprolactinoma and discrepant insulin-like growth factor (IGF-1) concentration (elevated) and growth hormone (GH) values during a 75 g oral glucose tolerance test (normal), that were measured to evaluate the co-secretion of GH by tumor. With the bromocriptin use, the patient achieved normalization of prolactin, but persisted with high levels of IGF1, suggesting to be subclinical acromegaly. After the development of new more sensitive GH assays, cases of discrepant GH and IGF-1 results have been observed and taken to some authors to suggest that GH nadir concentration during 75 g OGTT used to acromegaly diagnosis and treatment could be lower than values considered currently normal. Thus, if this is confirmed, subclinical and oligosymptomatic acromegaly cases could have earlier diagnoses.