Perinatal Outcomes in Obese Women with One Abnormal Value on 3-Hour Oral Glucose Tolerance Test

Objective This study aimed to determine if one abnormal value of four on the diagnostic 3-hour oral glucose tolerance test (OGTT) is associated with adverse perinatal outcomes in obese women. Study Design This is a secondary analysis of a prospective study of nulliparous women in eight geographic regions. Women with body mass index <30 kg/m2 and pregestational diabetes mellitus (GDM) were excluded. Four groups were compared: (1) normal 50-g 1-hour glucose screen, (2) elevated 1-hour glucose screen with normal 100-g 3-hour diagnostic OGTT, (3) elevated 1-hour glucose screen and one of four abnormal values on 3-hour OGTT, and (4) GDM. Using multivariable logistic regression adjusting for covariates, the women in the groups with dysglycemia were compared with those in the normal screen group for maternal and neonatal outcomes. Results Among 1,713 obese women, 1,418 (82.8%) had a normal 1-hour glucose screen, 125 (7.3%) had a normal 3-hour diagnostic OGTT, 72 (4.2%) had one abnormal value on their diagnostic OGTT, and 98 (5.7%) were diagnosed with GDM. The one abnormal value group had increased risk of large for gestational age (LGA) neonates (adjusted odds ratio [aOR] = 2.24, 95% confidence interval [CI]: 1.31–3.82), cesarean delivery (aOR = 2.19, 95% CI: 1.34–3.58), and hypertensive disorders of pregnancy (aOR = 2.19, 95% CI: 1.32–3.63) compared with normal screens. The one abnormal value group also had an increased risk of preterm birth <37 weeks (aOR = 2.63, 95% CI: 1.43–4.84), neonatal respiratory support (aOR = 2.38, 95% CI: 1.23–4.60), and neonatal hyperbilirubinemia (aOR = 2.00, 95% CI: 1.08–3.71). There was no association between one abnormal value with shoulder dystocia and neonatal hypoglycemia. Conclusion For obese women, one abnormal value on the 3-hour OGTT confers increased perinatal adverse outcomes. These women should be studied further to determine if nutrition counseling and closer fetal monitoring improve outcomes even in the absence of a diagnosis of GDM. Key Points

Glucose Concentrations from Continuous Glucose Monitoring Devices Compared to Those from Blood Plasma during an Oral Glucose Tolerance Test in Healthy Young Adults

Continuous glucose monitoring devices measure glucose in interstitial fluid. The devices are effective when used by patients with type 1 and 2 diabetes but are increasingly being used by researchers who are interested in the effects of various behaviours of glucose concentrations in healthy participants. Despite their more frequent application in this setting, the devices have not yet been validated for use under such conditions. A total of 124 healthy participants were recruited to a ten-day laboratory study. Each participant underwent four oral glucose tolerance tests, and a total of 3315 out of a possible 4960 paired samples were included in the final analysis. Bland–Altman plots and mean absolute relative differences were used to determine the agreement between the two methods. Bland–Altman analyses revealed that the continuous glucose monitoring devices had proportional bias (R = 0.028, p < 0.001) and a mean bias of −0.048 mmol/L, and device measurements were more variable as glucose concentrations increased. Ninety-nine per cent of paired values were in Zones A and B of the Parkes Error Grid plot, and there was an overall mean absolute relative difference of 16.2% (±15.8%). There was variability in the continuous glucose monitoring devices, and this variability was higher when glucose concentrations were higher. If researchers were to use continuous glucose monitoring devices to measure glucose concentrations during an oral glucose tolerance test in healthy participants, this variability would need to be considered.

Similar Metabolic Health in Overweight/Obese Individuals With Contrasting Metabolic Flexibility to an Oral Glucose Tolerance Test

Background: Low metabolic flexibility (MetF) may be an underlying factor for metabolic health impairment. Individuals with low MetF are thus expected to have worse metabolic health than subjects with high MetF. Therefore, we aimed to compare metabolic health in individuals with contrasting MetF to an oral glucose tolerance test (OGTT).Methods: In individuals with excess body weight, we measured MetF as the change in respiratory quotient (RQ) from fasting to 1 h after ingestion of a 75-g glucose load (i.e., OGTT). Individuals were then grouped into low and high MetF (Low-MetF n = 12; High-MetF n = 13). The groups had similar body mass index, body fat, sex, age, and maximum oxygen uptake. Metabolic health markers (clinical markers, insulin sensitivity/resistance, abdominal fat, and intrahepatic fat) were compared between groups.Results: Fasting glucose, triglycerides (TG), and high-density lipoprotein (HDL) were similar between groups. So were insulin sensitivity/resistance, visceral, and intrahepatic fat. Nevertheless, High-MetF individuals had higher diastolic blood pressure, a larger drop in TG concentration during the OGTT, and a borderline significant (P = 0.05) higher Subcutaneous Adipose Tissue (SAT). Further, compared to Low-MetF, High-MetF individuals had an about 2-fold steeper slope for the relationship between SAT and fat mass index.Conclusion: Individuals with contrasting MetF to an OGTT had similar metabolic health. Yet High-MetF appears related to enhanced circulating TG clearance and enlarged subcutaneous fat.

The association between an oral glucose tolerance test performed at term pregnancy and obstetric outcomes

Aims Assessing the value of oral glucose tolerance test performed at term pregnancy in identifying obstetric complications. Methods Retrospective cohort study of women with a normal 50 g glucose challenge test who also had an oral glucose tolerance test at term (defined as at or after 37 weeks of gestation). Comparison between the pathological and normal oral glucose tolerance test groups was performed. Results The mean glucose in the glucose challenge test of women in the normal oral glucose tolerance test ( n = 256) group was lower than that in the pathological oral glucose tolerance test ( N = 16) group (105 ± 17 mg/dl (5.8 ± 0.9 mmol/l) vs 117 ± 13 mg/dl (6.5 ± 0.7 mmol/l), p = 0.007). Relevant obstetrical complications did not differ significantly between the groups. Of note, in the pathological oral glucose tolerance test group only one woman delivered a macrosomic infant. Conclusions A pathological oral glucose tolerance test performed at term was unable to identify women at risk for impaired glucose metabolism-related obstetric complications and is therefore of limited clinical value and seems to be unjustified.