Plasma Glucose Concentrations in Different Sampling Tubes Measured on Different Glucose Analysers.

INTRODUCTION: The German Diabetes Association recommends using sampling tubes with citrate and fluoride additives to diagnose diabetes by oral glucose tolerance test to inhibit glycolysis. The effect of different tubes on measurement results was assessed. MATERIALS AND METHODS: In a first study, an oral glucose tolerance test was performed on 41 participants without anamnestically known diabetes. Venous blood was sampled in two different tubes with citrate/fluoride additives from different manufacturers and one with only lithium-heparin additive. A second study with 42 participants was performed to verify the initial results with an adapted design, in which a third tube with citrate buffer was used, and glucose measurements were performed on two additional devices of another analyser model. Samples were centrifuged either immediately (<5 min incubation time) or after 20 min or 4 h. All glucose measurements were performed in plasma. Glucose concentrations in lithium-heparin tubes with<5 min incubation time served as baseline concentrations. RESULTS: In the first study, glucose concentrations in one of the citrate/fluoride tubes were similar to the baseline. In the other citrate/fluoride tube, markedly lower concentrations (approximately - 5 mg/dL (- 0.28 mmol/L)) were measured. This was reproduced in the verification study for the same analyser, but not with the other analyser model. Lithium-heparin tubes centrifuged after 20 and 240 min showed systematically lower glucose concentrations. CONCLUSIONS: The results confirm that glycolysis can be effectively inhibited in citrate/fluoride-containing sampling tubes. However, glucose measurement results of one analyser showed a relevant negative bias in tubes containing liquid citrate buffer.

Antecubital Vein Cannula Position Impacts Assessment of Forearm Glucose Uptake During an Oral Glucose Challenge in Healthy Volunteers.

INTRODUCTION: Skeletal muscle is a major site for whole-body glucose disposal, and determination of skeletal muscle glucose uptake is an important metabolic measurement, particularly in research focussed on interventions that impact muscle insulin sensitivity. Calculating arterial-venous difference in blood glucose can be used as an indirect measure for assessing glucose uptake. However, the possibility of multiple tissues contributing to the composition of venous blood, and the differential in glucose uptake kinetics between tissue types, suggests that sampling from different vein sites could influence the estimation of glucose uptake. This study aimed to determine the impact of venous cannula position on calculated forearm glucose uptake following an oral glucose challenge in resting and post-exercise states. MATERIALS AND METHODS: In 9 young, lean, males, the impact of sampling blood from two antecubital vein positions; the perforating vein ('perforating' visit) and, at the bifurcation of superficial and perforating veins ('bifurcation' visit), was assessed. Brachial artery blood flow and arterialised-venous and venous blood glucose concentrations were measured in 3 physiological states; resting-fasted, resting-fed, and fed following intermittent forearm muscle contraction (fed-exercise). RESULTS: Following glucose ingestion, forearm glucose uptake area under the curve was greater for the 'perforating' than for the 'bifurcation' visit in the resting-fed (5.92±1.56 vs. 3.69±1.35 mmol/60 min, P<0.01) and fed-exercise (17.38±7.73 vs. 11.40±7.31 mmol/75 min, P<0.05) states. DISCUSSION: Antecubital vein cannula position impacts calculated postprandial forearm glucose uptake. These findings have implications for longitudinal intervention studies where serial determination of forearm glucose uptake is required.

Precision and accuracy of hyperglycemic clamps in a multicenter study.

Application of glucose clamp methodologies in multicenter studies brings challenges for standardization. The Restoring Insulin Secretion (RISE) Consortium implemented a hyperglycemic clamp protocol across seven centers using a combination of technical and management approaches to achieve standardization. Two-stage hyperglycemic clamps with glucose targets of 200 mg/dL and >450 mg/dL were performed utilizing a centralized spreadsheet-based algorithm that guided dextrose infusion rates using bedside plasma glucose measurements. Clamp operators received initial and repeated training with ongoing feedback based on surveillance of clamp performance. The precision and accuracy of the achieved stage-specific glucose targets were evaluated, including differences by study center. We also evaluated robustness of the method to baseline physiologic differences and on-study treatment effects. The RISE approach produced high overall precision (3%-9% variance in achieved plasma glucose from target at various times across the procedure) and accuracy (SD < 10% overall). Statistically significant but numerically small differences in achieved target glucose concentrations were observed across study centers, within the magnitude of the observed technical variability. Variation of the achieved target glucose over time in placebo-treated individuals was low (<3% variation), and the method was robust to differences in baseline physiology (youth vs. adult, IGT vs. diabetes status) and differences in physiology induced by study treatments. The RISE approach to standardization of the hyperglycemic clamp methodology across multiple study centers produced technically excellent standardization of achieved glucose concentrations. This approach provides a reliable method for implementing glucose clamp methodology across multiple study centers.NEW & NOTEWORTHY The Restoring Insulin Secretion (RISE) study centers undertook hyperglycemic clamps using a simplified methodology and a decision guidance algorithm implemented in an easy-to-use spreadsheet. This approach, combined with active management including ongoing central data surveillance and routine feedback to study centers, produced technically excellent standardization of achieved glucose concentrations on repeat studies within and across study centers.

Early Versus Routine Oral Glucose Tolerance Test in Women With Intermediate Hyperglycemia at First Prenatal Visit: A Retrospective Cohort Study in China.

Background and Objectives: Intermediate hyperglycemia in the first half of pregnancy, defined as a fasting plasma glucose level between 5.1- 6.9 mM, increases the risk of gestational diabetes mellitus, but clinical evidence for further management is lacking. We aim to evaluate the effectiveness of an early oral glucose tolerance test (OGTT) followed by the identification of intermediate hyperglycemia on pregnancy outcomes in real world setting. Subjects and Methods: A retrospective cohort study was conducted at the Obstetrics and Gynecology Hospital, Shanghai, China, between 2013 and 2017. Women with intermediate hyperglycemia at the first prenatal visit were identified and underwent an immediate (within one week) or a routine OGTT (24-28 gw) according to their wishes and received nutrition and exercise advice. Women diagnosed of gestational diabetes (GDM) were managed by standard interventions. Primary outcome was larger for gestational age (LGA). Secondary outcomes were primary cesarean delivery, preterm birth, shoulder dystocia or forceps delivery, preeclampsia, neonatal hypoglycemia, hyperbilirubinemia, and low Apgar score. Logistic regressions with or without a further propensity score-matched analysis were performed. Results: Among 42406 women involved, 1104 (2.6%) with intermediate hyperglycemia at the first prenatal visit were identified, of whom 176 (15.9%) underwent an early OGTT and 741 (67.1%) received a routine OGTT. Logistic regression showed that an early OGTT was not significantly associated with an altered risk of LGA (adjusted OR 1.13, 95% CI 0.73-1.75) but was related to an increased odds for neonatal hyperbilirubinemia (adjusted OR 2.89; 95% CI 1.55-5.37). No significant associations were observed for other secondary outcomes. These trends remained consistent in propensity score-matched models. Conclusions: Our data from a real-world setting did not support that an early OGTT among women with intermediate hyperglycemia at the first prenatal visit improved pregnancy outcomes.

Reconsidering the HbA1c Cutoff for Diabetes Diagnosis Based on a Large Chinese Cohort.

INTRODUCTION: The HbA1c has been considered as the 'gold standard' in diabetes diagnosis and management, however, age, gender and body mass index (BMI) might have certain effects on HbA1c. We are aiming to further investigate the correlation between age and HbA1c, and whether it was affected by gender and BMI. METHODS: A cross-sectional survey including 135,893 nondiabetic individuals who took the physical examination between 2013 and 2017 was conducted. The subjects were grouped by gender, age and BMI, and the interactive and independent effects of the 3 factors on the HbA1c were detected. The median and 95% confidence interval (CI) of HbA1c levels were calculated. RESULTS: The HbA1c levels gradually increased along with age, both in female and male, and there is a positive association between BMI and the HbA1c. The difference on HbA1c in gender was associated with both age and BMI, the age-related increase in HbAlc was accentuated in the subgroup with higher BMI, and there was a marked accentuation of the positive association between BMI and HbA1c as age increased. In almost all the young and middle-aged (aged 20-59) subgroups, the 97.5th percentiles of HbA1c levels were lower than 6.5%, suggesting that the single HbA1c cutoff value is probably not applicable to the young and middle-aged population. CONCLUSIONS: We recommend that the effects of age, gender and BMI should be taken into consideration when using HbA1c for the diagnosis and management of diabetes, especially in the young and middle-aged population.

Adherence rates to a prediction tool identifying women with an increased gestational diabetes risk: An implementation study.

OBJECTIVE: The best screening strategy for gestational diabetes mellitus (GDM) remains a topic of debate. Several organizations made a statement in favor of universal screening, but the volume of oral glucose tolerance tests (OGTT) required may burden healthcare systems. As a result, many countries still rely on selective screening using a checklist of risk factors, but reported diagnostic characteristics vary. Moreover, women's discomfort due to an OGTT is often neglected. Since 2017, obstetric healthcare professionals in a Dutch region assessed women's GDM risk with a prediction model and counseled those with an increased risk regarding an OGTT. METHODS: From 2017 to 2018, 865 women were recruited in a multicenter prospective cohort. RESULTS: In total, 385 women (48%) had an increased predicted GDM risk. Of all women, 78% reported that their healthcare professional discussed their GDM risk. Predicted GDM risks were positively correlated with conducting an OGTT. CONCLUSION: Implementation of a GDM prediction model resulted in moderate rates of OGTTs performed in general, but high rates in high-risk women. As 25% of women experienced discomfort from the OGTT, a selective screening strategy based on a prediction model with a high detection rate may be an interesting alternative to universal screening. STUDY COHORT REGISTRATION: Netherlands Trial Register: NTR4143; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4143.

Development of a fasting blood glucose-based strategy to diagnose women with gestational diabetes mellitus at increased risk of adverse outcomes in a COVID-19 environment.

OBJECTIVE: To evaluate the role of fasting blood glucose (FBG) to minimise the use of the oral glucose tolerance test in pregnancy (POGTT) for the diagnosis of gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: We analysed the POGTTs of 26,242 pregnant women in Queensland, Australia, performed between 1 January 2015 and 30 June 2015. A receiver operator characteristics (ROC) assessment was undertaken to indicate the FBG level that most effectively identified women at low risk of an abnormal result. RESULTS: There were 3,946 (15.0%) patients having GDM with 2,262 (8.6%) having FBG ≥ 5.1mmol/l. The ROC identified FBG levels >4.6mmol/l having the best specificity (77%) and sensitivity (54%) for elevated 1 and/or 2hr BGLs. There were 19,321 (73.7%) women having FBG < 4.7mmol/l with a prevalence of GDM of 4.0%, less than 1/3rd the overall rate. Only 4,638 (17.7%) women having FBGs from 4.7-5.0mmol/l would require further evaluation to confirm or exclude the diagnosis. CONCLUSION: This contemporary study of women across the state of Queensland, Australia suggests the FBG can be used effectively to define glucose tolerance in pregnancy, minimising their contact with pathology laboratories and potential exposure to the corona virus. This analysis, used in conjunction with outcome data from the HAPO study, provides reassurance to women and their health professionals that FBG < 4.7mmol/l has both a low rate of abnormal glucose tolerance and minimal adverse pregnancy-associated complications.

Comparison of oral glucose tolerance test and ambulatory glycaemic profiles in pregnant women in Uganda with gestational diabetes using the FreeStyle Libre flash glucose monitoring system.

BACKGROUND: The diagnosis of hyperglycaemia in sub-Saharan Africa (SSA) is challenging. Blood glucose levels obtained during oral glucose tolerance test (OGTT) may not reflect home glycaemic profiles. We compare OGTT results with home glycaemic profiles obtained using the FreeStyle Libre continuous glucose monitoring device (FSL-CGM). METHODS: Twenty-eight women (20 with gestational diabetes [GDM], 8 controls) were recruited following OGTT between 24 and 28 weeks of gestation. All women wore the FSL-CGM device for 48-96 h at home in early third trimester, and recorded a meal diary. OGTT was repeated on the final day of FSL-CGM recording. OGTT results were compared with ambulatory glycaemic variables, and repeat OGTT was undertaken whilst wearing FSL-CGM to determine accuracy of the device. RESULTS: FSL-CGM results were available for 27/28 women with mean data capture 92.8%. There were significant differences in the ambulatory fasting, post-prandial peaks, and mean glucose between controls in whom both primary and secondary OGTT was normal (n = 6) and those with two abnormal OGTTs or "true" GDM (n = 7). There was no difference in ambulatory mean glucose between these controls and the 13 women who had an abnormal primary OGTT and normal repeat OGTT. These participants had significantly lower body mass index (BMI) than the true GDM group (29.0 Vs 36.3 kg/m2, p-value 0.014). Paired OGTT/FSL-CGM readings revealed a Mean Absolute difference (MAD) -0.58 mmol/L and Mean Absolute Relative Difference (MARD) -11.9%. Bland-Altman plot suggests FSL-CGM underestimated blood glucose by approximately 0.78 mmol/L. CONCLUSION: Diagnosis of GDM on a single OGTT identifies a proportion of women who do not have a significantly higher home glucose levels than controls. This raises questions about factors which may affect the reproducibility of OGTT in this population, including food insecurity and atypical phenotypes of diabetes. More investigation is needed to understand the suitability of the OGTT as a diagnostic test in sub-Saharan Africa.

Improved Detection of Abnormal Glucose Tolerance in Africans: The Value of Combining Hemoglobin A1c With Glycated Albumin.

OBJECTIVE: In African-born Blacks living in America, we determined by BMI category 1) prevalence of abnormal glucose tolerance (Abnl-GT) and 2) diagnostic value and reproducibility of hemoglobin A1c (HbA1c), fructosamine, and glycated albumin (GA). RESEARCH DESIGN AND METHODS: Participants (n = 416; male, 66%; BMI 27.7 ± 4.5 kg/m2 [mean ± SD]) had an oral glucose tolerance test with HbA1c, GA, and fructosamine assayed. These glycemic markers were repeated 11 ± 7 days later. Abnl-GT diagnosis required 0 h ≥5.6 mmol/L (≥100 mg/dL) and/or 2 h ≥7.8 mmol/L (≥140 mg/dL). Thresholds for HbA1c, GA, and fructosamine were the values at the 75th percentile for the population (39 mmol/mol [5.7%], 14.2%, and 234 µmol/L, respectively). RESULTS: Abnl-GT prevalence in the nonobese was 34% versus 42% in the obese (P = 0.124). Reproducibility was excellent for HbA1c and GA (both κ ≥ 0.8), but moderate for fructosamine (κ = 0.6). Focusing on HbA1c and GA in the nonobese, we found as single tests the sensitivities of HbA1c and GA were 36% versus 37% (P = 0.529). Combining HbA1c and GA, sensitivity increased to 58% because GA identified 37% of Africans with Abnl-GT not detected by HbA1c (P value for both tests vs. HbA1c alone was <0.001). For the obese, sensitivities for HbA1c, GA, and the combined tests were 60%, 27%, and 67%, respectively. Combined test sensitivity did not differ from HbA1c alone (P = 0.25) because GA detected only 10% of obese Africans with Abnl-GT not detected by HbA1c. CONCLUSIONS: Adding GA to HbA1c improves detection of Abnl-GT in nonobese Africans.

Two criteria of oral glucose tolerance test to diagnose gestational diabetes mellitus.

OBJECTIVE: To evaluate two different criteria, one or two cut-off values, of oral glucose tolerance test with 75g of glucose for the diagnosis of gestational diabetes mellitus. METHODS: A cross-sectional study involving 120 records of pregnant women who received prenatal care at the service of a Brazilian university was carried out. Bivariate analysis of obstetric and perinatal outcomes was performed using the chi-square test. RESULTS: Considering criterion I, 12.5% of patients were diagnosed with gestational diabetes mellitus. Patients were 3.57 times more likely to have a large fetus for the gestational age at birth (p=0.038). Using criterion II, gestational diabetes mellitus was diagnosed in 5.8% of patients, macrosomia was 7.73 times more likely to be found in the presence of gestational diabetes mellitus (p=0.004), and a large fetus for the gestational age at birth was 8.17 times more likely (p=0.004). CONCLUSIONS: There was a difference in the prevalence of gestational diabetes mellitus between the two criteria analyzed. The new criterion proposed increased prevalence.

Comparison of criteria of International Association of Diabetes and Pregnancy Study Groups (IADPSG) with National Institute for Health and Care Excellence (NICE) for diagnosis of gestational diabetes mellitus.

BACKGROUND: Different screening procedures and diagnostic criteria are being followed in the same as well as in different countries with no single standard criteria established for diagnosis of GDM. So far, there are no studies in the Indian population comparing IADPSG with NICE criteria. OBJECTIVE: To compare International Association of Pregnancy and Study Groups (IADPSG) criteria with the National Institute for Health and Care Excellence (NICE) for diagnosis of gestational diabetes mellitus and its influence on maternal and perinatal outcomes. METHOD: This prospective observational study was conducted in the Department of Obstetrics and Gynaecology of a tertiary care institute in South India from March 2017 to October 2018. Six-hundred and eighty women with or without risk factors for GDM were recruited in the study and screened for GDM based on IADPSG and NICE criteria. Women with preexisting diabetes mellitus or with fasting plasma glucose ≥ 126 mg/dl were excluded. RESULTS: The overall prevalence of GDM in our study was 27.2% by either IADPSG/NICE criteria. In this study, 25.1% women and 11.6% women were diagnosed as GDM using IADPSG and NICE criteria, respectively. The level of agreement between the two diagnostic criteria was found to be poor in our study and was statistically significant (kappa = 0.429, p < 0.001). Women testing IADPSG-positive NICE-negative had a higher risk of GHTN, abortions, PROM, preterm delivery, caesarean section and congenital anomalies, meconium-stained liquor, and low Apgar scores at 1 min when compared to non GDM group. In addition, except for preterm delivery, women diagnosed as GDM by both IADPSG and NICE criteria had adverse outcomes such as preeclampsia, urinary tract infection, and polyhydramnios. Women diagnosed as GDM in IADPSG-negative NICE-positive had no significant adverse maternal or perinatal outcomes. CONCLUSIONS: IADPSG criteria appear to be more robust than NICE criteria for diagnosis of GDM. Women with substantial risk of maternal and perinatal outcomes are better identified by IADPSG criteria who would have been missed if NICE criteria was used.

Strict Preanalytical Oral Glucose Tolerance Test Blood Sample Handling Is Essential for Diagnosing Gestational Diabetes Mellitus.

OBJECTIVE: Preanalytical processing of blood samples can affect plasma glucose measurement because ongoing glycolysis by cells prior to centrifugation can lower its concentration. In June 2017, ACT Pathology changed the processing of oral glucose tolerance test (OGTT) blood samples for pregnant women from a delayed to an early centrifugation protocol. The effect of this change on the rate of gestational diabetes mellitus (GDM) diagnosis was determined. RESEARCH DESIGN AND METHODS: All pregnant women in the Australian Capital Territory (ACT) are recommended for GDM testing with a 75-g OGTT using the World Health Organization diagnostic criteria. From January 2015 to May 2017, OGTT samples were collected into sodium fluoride (NaF) tubes and kept at room temperature until completion of the test (delayed centrifugation). From June 2017 to October 2018, OGTT samples in NaF tubes were centrifuged within 10 min (early centrifugation). RESULTS: A total of 7,509 women were tested with the delayed centrifugation protocol and 4,808 with the early centrifugation protocol. The mean glucose concentrations for the fasting, 1-h, and 2-h OGTT samples were, respectively, 0.24 mmol/L (5.4%), 0.34 mmol/L (4.9%), and 0.16 mmol/L (2.3%) higher using the early centrifugation protocol (P < 0.0001 for all), increasing the GDM diagnosis rate from 11.6% (n = 869/7,509) to 20.6% (n = 1,007/4,887). CONCLUSIONS: The findings of this study highlight the critical importance of the preanalytical processing protocol of OGTT blood samples used for diagnosing GDM. Delay in centrifuging of blood collected into NaF tubes will result in substantially lower rates of diagnosis than if blood is centrifuged early.

The Optimized Calculation Method for Insulin Dosage in an Insulin Tolerance Test (ITT): A Randomized Parallel Control Study.

Objective: To explore the most suitable calculation method for insulin dosage in an insulin tolerance test (ITT) and to evaluate the clinical application value of the optimization coefficient (γ). Methods: In this study, 140 adult patients with congenital growth hormone deficiency (GHD) or acquired hypopituitarism were randomized into the following two groups: the conventional group (n = 70) and the optimized group (n = 70). Oral glucose tolerance tests (OGTTs), insulin release tests (IRTs), and ITTs were conducted. For ITTs, insulin doses were the product of body weight (kg) and related coefficient (0.15 IU/kg for the control group and γ IU/kg for the optimized group, respectively). Notably, γ was defined as -0.034 + 0.000176 × AUCINS + 0.009846 × BMI, which was based on our previous study. Results: In the ITTs, the rate of achieving adequate hypoglycemia with a single insulin dose was significantly higher for the optimized group compared with the conventional group (92.9 vs. 60.0%, P < 0.001). The optimized group required higher initial doses of insulin (0.23 IU/kg). Meanwhile, the two groups did not differ significantly in their nadir blood glucose (1.9 vs. 1.9 mmol/L, P = 0.828). Conclusion: This study confirmed that the proposed optimized calculation method for insulin dosage in ITTs led to more efficient hypoglycemia achievement, without increasing the incidence of serious adverse events.

Clinical and Public Health Implications of 2019 Endocrine Society Guidelines for Diagnosis of Diabetes in Older Adults.

OBJECTIVE: Screening for diabetes is typically done using hemoglobin A1c (HbA1c) or fasting plasma glucose (FPG). The 2019 Endocrine Society guidelines recommend further testing using an oral glucose tolerance test (OGTT) in older adults with prediabetic HbA1c or FPG. We evaluated the impact of this recommendation on diabetes prevalence, eligibility for glucose-lowering treatment, and estimated cost of implementation in a nationally representative sample. RESEARCH DESIGN AND METHODS: We included 2,236 adults aged ≥65 years without known diabetes from the 2005-2016 National Health and Nutrition Examination Survey. Diabetes was defined using: 1) the Endocrine Society approach (HbA1c ≥6.5%, FPG ≥126 mg/dL, or 2-h plasma glucose ≥200 mg/dL among those with HbA1c 5.7-6.4% or FPG 100-125 mg/dL); and 2) a standard approach (HbA1c ≥6.5% or FPG ≥126 mg/dL). Treatment eligibility was defined using HbA1c cut points (≥7% to ≥9%). OGTT screening costs were estimated using Medicare fee schedules. RESULTS: Diabetes prevalence was 15.7% (∼5.0 million) using the Endocrine Society's approach and 7.3% (∼2.3 million) using the standard approach. Treatment eligibility ranged from 5.4% to 0.06% and 11.8% to 1.3% for diabetes cases identified through the Endocrine Society or standard approach, respectively. By definition, diabetes identified exclusively through the Endocrine Society approach had HbA11c <6.5% and would not be recommended for glucose-lowering treatment. Screening all older adults with prediabetic HbA1c/FPG (∼18.3 million) with OGTT could cost between $737 million and $1.7 billion. CONCLUSIONS: Adopting the 2019 Endocrine Society guidelines would substantially increase the number of older adults classified as having diabetes, require significant financial resources, but likely offer limited benefits.

Detection of diabetes and prediabetes using glycosylated hemoglobin in Chinese adults living in Shanghai: A prospective analysis.

BACKGROUND: This study aimed to evaluate the discriminative abilities of glycosylated hemoglobin (HbA1c) and to examine the optimal HbA1c cutoff values for diabetes and prediabetes in Chinese adults. METHODS: Data of a population-based cohort of Chinese adults aged ≥40 years living in Jiading District in Shanghai were used. At baseline, 9389 and 7241 participants were included to identify the optimal HbA1c cutoff values for diabetes and prediabetes, respectively using the 1999 World Health Organization criteria as reference. In addition, the follow-up data on incident diabetes of 4538 participants were used to determine the HbA1c cutoff value for prediabetes using the development of diabetes as reference. The discriminative abilities of HbA1c were evaluated using receiver operating characteristic (ROC) curves, and the optimal cutoff values were determined by Youden's index. RESULTS: The areas under the ROC curves were 0.849 for diabetes, 0.614 for prediabetes using baseline data, and 0.648 for prediabetes using follow-up data. An HbA1c cutoff value of 6.0% had the largest Youden's index to diagnose diabetes with a sensitivity of 70.2% and a specificity of 87.4%. An HbA1c cutoff value of 5.6% was indicated for prediabetes using both baseline and follow-up data. However, the sensitivity and specificity were both low (55.4% and 61.1% using an oral glucose tolerance test as reference, 64.6% and 57.1% using incident diabetes as reference). CONCLUSIONS: An HbA1c value ≥6.0% could be used to detect diabetes in Chinese adults aged ≥40 years. However, although an HbA1c value of 5.6% to 5.9% was indicated in this study, the overall discrimination of HbA1c for prediabetes was poor.

Two criteria of oral glucose tolerance test to diagnose gestational diabetes mellitus

SUMMARY OBJECTIVE To evaluate two different criteria, one or two cut-off values, of oral glucose tolerance test with 75g of glucose for the diagnosis of gestational diabetes mellitus. METHODS A cross-sectional study involving 120 records of pregnant women who received prenatal care at the service of a Brazilian university was carried out. Bivariate analysis of obstetric and perinatal outcomes was performed using the chi-square test. RESULTS Considering criterion I, 12.5% of patients were diagnosed with gestational diabetes mellitus. Patients were 3.57 times more likely to have a large fetus for the gestational age at birth (p=0.038). Using criterion II, gestational diabetes mellitus was diagnosed in 5.8% of patients, macrosomia was 7.73 times more likely to be found in the presence of gestational diabetes mellitus (p=0.004), and a large fetus for the gestational age at birth was 8.17 times more likely (p=0.004). CONCLUSIONS There was a difference in the prevalence of gestational diabetes mellitus between the two criteria analyzed. The new criterion proposed increased prevalence.

RESUMO OBJETIVO Avaliar dois critérios distintos, um ou dois valores de corte, do teste oral de tolerância à glicose com 75 g de glicose para o diagnóstico de diabetes mellitus gestacional. Métodos Estudo transversal envolvendo 120 prontuários de gestantes que realizaram pré-natal em um ambulatório de uma universidade brasileira. Análise bivariada dos resultados obstétricos e perinatais foi realizada pelo teste do qui-quadrado. Resultados Considerando o critério I, 12,5% das pacientes foram diagnosticadas com diabetes mellitus gestacional. As pacientes apresentaram uma chance 3,57 maior de ter um feto grande para a idade gestacional (p=0,038). Utilizando o critério II, o diabetes mellitus gestacional foi diagnosticado em 5,8% das pacientes. Mediante esse critério diagnóstico, a chance de macrossomia foi 7,73 vezes mais provável na presença de diabetes mellitus gestacional (p=0,004) e a chance de um feto grande para a idade gestacional foi 8,17 vezes maior de ocorrer (p=0,004). Conclusões Observou-se diferença na prevalência de diabetes melittus gestacional entre os dois critérios analisados, sendo que o novo critério proposto aumentou a prevalência.

Impact of mismatches in HbA1c vs glucose values on the diagnostic classification of diabetes and prediabetes.

AIMS: To determine whether HbA1c mismatches (HbA1c levels that are higher or lower than expected for the average glucose levels in different individuals) could lead to errors if diagnostic classification is based only on HbA1c levels. METHODS: In a cross-sectional study, 3106 participants without known diabetes underwent a 75-g oral glucose tolerance test (fasting glucose and 2-h glucose) and a 50-g glucose challenge test (1-h glucose) on separate days. They were classified by oral glucose tolerance test results as having: normal glucose metabolism; prediabetes; or diabetes. Predicted HbA1c was determined from the linear regression modelling the relationship between observed HbA1c and average glucose (mean of fasting glucose and 2-h glucose from the oral glucose tolerance test, and 1-h glucose from the glucose challenge test) within oral glucose tolerance test groups. The haemoglobin glycation index was calculated as [observed - predicted HbA1c ], and divided into low, intermediate and high haemoglobin glycation index mismatch tertiles. RESULTS: Those participants with higher mismatches were more likely to be black, to be men, to be older, and to have higher BMI (all P<0.001). Using oral glucose tolerance test criteria, the distribution of normal glucose metabolism, prediabetes and diabetes was similar across mismatch tertiles; however, using HbA1c criteria, the participants with low mismatches were classified as 97% normal glucose metabolism, 3% prediabetes and 0% diabetes, i.e. mostly normal, while those with high mismatches were classified as 13% normal glucose metabolism, 77% prediabetes and 10% diabetes, i.e. mostly abnormal (P<0.001). CONCLUSIONS: Measuring only HbA1c could lead to under-diagnosis in people with low mismatches and over-diagnosis in those with high mismatches. Additional oral glucose tolerance tests and/or fasting glucose testing to complement HbA1c in diagnostic classification should be performed in most individuals.