The Analytical Reliability of the Oral Glucose Tolerance Test for the Diagnosis of Gestational Diabetes: An Observational, Retrospective Study in a Caucasian Population

Enzymatic detection of α-hydroxybutyrate, an important marker of insulin resistance, and comparison with LC-MS/MS detection

Aim

The metabolite α-hydroxybutyrate (α-HB) is an important marker of insulin resistance and impaired glucose tolerance allowing to identify patients at risk of developing diabetes and related metabolic disorders before any symptoms become apparent. At present, its exact quantification requires mass spectrometry (LC-MS), which is not compatible with routine laboratory use. Accordingly, a simple enzymatic-based method was assessed and its applicability and measuring accuracy compared with LC-MS was investigated.

Methods

Standards, serum, and plasma samples containing α-HB were prepared with routine procedures and their α-HB contents measured with the XpressGT® enzymatic test kit photometrically or with LC-MS and multiple reaction monitoring.

Results

α-HB detection with XpressGT® yielded highly linear calibration curves and 102 % recovery of stocks added to commercial samples. Stability of the analyte in serum and plasma samples prepared with various anti-coagulants was >90 % after 46 h for several widely used preparations and recovery after 3 freeze-thaw cycles was ≥95 % with these anti-coagulants. A direct comparison of 75 samples indicated very good agreement of α-HB levels determined by both methods, 86 % of XpressGT® samples being within ±20 % of LC-MS values and even 93 % within ±20 % considering only samples above 30 μM concentration.

Conclusion

XpressGT®-based detection of α-HB is an easily applicable method which can be used for accurate and reliable quantification of the metabolite in clinical practice. Routine α-HB determination in patients at risk of developing diabetes would allow early establishment of preventive measures or pharmacological intervention reducing the risk for the onset of serious diabetes-related health problems.

Comparing the screening methods for gestational diabetes mellitus before and during the COVID-19 pandemic: A systematic review

BACKGROUND

The oral glucose tolerance test (OGTT) is the gold standard for detecting gestational diabetes mellitus (GDM). However, during the COVID-19 pandemic, screening practices were reevaluated due to the risk of infection associated with the prolonged hospital visit required for the OGTT. Some countries have published novel screening protocols for GDM, suggesting the utilization of hemoglobin A1c (HbA1c), random plasma glucose (RPG), or fasting plasma glucose (FPG) in favor of OGTTs during the pandemic. Therefore, differences in screening methods before and after the epidemic need to be examined.

METHODS

A systematic search was carried out across five electronic databases (Cinahl, Medline, Embase, Pubmed, and Web of Science) between 2016 and 2023. The Critical Appraisal Skills Programme (CASP) checklist for cohort studies was used to evaluate the quality of included papers.

RESULTS

A total of 13 eligible studies were included. Prior to the COVID-19 pandemic, the OGTT was the recommended measure to screen GDM, internationally based on various official guidelines. During the pandemic, it was recommended that HbA1c or FPG, or RPG be used as a substitute for OGTTs. However, the new methods have low sensitivity, may not reflect accurately the prevalence of GDM, and may lead to many false-negative results in women and to adverse pregnancy and neonatal outcomes.

CONCLUSION

The new screening methods for GDM have poor accuracy and a high risk of adverse pregnancy outcomes. Comparatively, targeted screening tests to detect GDM according to the risk level are more effective in an emergency. In the future, the alternatives to OGTTs still need to be further explored in more depth.

Potential antimicrobial activity of camel milk as a traditional functional food against foodborne pathogens in vivo and in vitro

Foodborne pathogens are a leading cause of mortality worldwide. Therefore, strategies focused on functional foods are urgently required to tackle this issue. As a result, camel milk is one of the most important traditional functional foods since it contains a variety of bioactive components, which all have antimicrobial activity against foodborne pathogens. The study aims to investigate the potential antimicrobial activity of raw camel milk against foodborne pathogens in both in vitro agar well diffusion and infected mice, especially Listeria monocytogenes, Staphylococcus aureus, Salmonella Typhimurium and Escherichia coli, particularly in societies that rely on consuming camel milk in its raw form. A total of eighty C57BL/6 mice were divided into ten groups and gavaged with or without camel milk for two consecutive weeks. A blood plasma analysis and serum insulin levels were measured. Histological investigations of the liver, pancreas, kidney, spleen, lung and testicles were also performed. In both in vivo and in vitro studies when compared to other pathogenic bacteria, E. coli was the most affected by raw camel milk, with a significant clear zone of 2.9 ± 0.13 cm in vitro and in all measured parameters in vivo (p < 0.05). As a result, we advocated for further research to improve camel breeding, raise milk yield and extend its reproductive capability as one of the most important farm animals.

Non-Invasive Glucose Sensing Technologies and Products: A Comprehensive Review for Researchers and Clinicians

Diabetes Mellitus incidence and its negative outcomes have dramatically increased worldwide and are expected to further increase in the future due to a combination of environmental and social factors. Several methods of measuring glucose concentration in various body compartments have been described in the literature over the years. Continuous advances in technology open the road to novel measuring methods and innovative measurement sites. The aim of this comprehensive review is to report all the methods and products for non-invasive glucose measurement described in the literature over the past five years that have been tested on both human subjects/samples and tissue models. A literature review was performed in the MDPI database, with 243 articles reviewed and 124 included in a narrative summary. Different comparisons of techniques focused on the mechanism of action, measurement site, and machine learning application, outlining the main advantages and disadvantages described/expected so far. This review represents a comprehensive guide for clinicians and industrial designers to sum the most recent results in non-invasive glucose sensing techniques' research and production to aid the progress in this promising field.

Sensitivity, specificity, and diagnostic accuracy of WHO 2013 criteria for diagnosis of gestational diabetes mellitus in low risk early pregnancies: international, prospective, multicentre cohort study

Objective

To evaluate the predictability of gestational diabetes mellitus wth a 75 g oral glucose tolerance test (OGTT) in early pregnancy, based on the 2013 criteria of the World Health Organization, and to test newly proposed cut-off values.

Design

International, prospective, multicentre cohort study.

Setting

Six university or cantonal departments in Austria, Germany, and Switzerland, from 1 May 2016 to 31 January 2019.

Participants

Low risk cohort of 829 participants aged 18-45 years with singleton pregnancies attending first trimester screening and consenting to have an early 75 g OGTT at 12-15 weeks of gestation. Participants and healthcare providers were blinded to the results.

Main outcome measures

Fasting, one hour, and two hour plasma glucose concentrations after an early 75 g OGTT (12-15 weeks of gestation) and a late 75 g OGTT (24-28 weeks of gestation).

Results

Of 636 participants, 74 (12%) developed gestational diabetes mellitus, according to World Health Organization 2013 criteria, at 24-28 weeks of gestation. Applying WHO 2013 criteria to the early OGTT with at least one abnormal value gave a low sensitivity of 0.35 (95% confidence interval 0.24 to 0.47), high specificity of 0.96 (0.95 to 0.98), positive predictive value of 0.57 (0.41 to 0.71), negative predictive value of 0.92 (0.89 to 0.94), positive likelihood ratio of 10.46 (6.21 to 17.63), negative likelihood ratio of 0.65 (0.55 to 0.78), and diagnostic odds ratio of 15.98 (8.38 to 30.47). Lowering the postload glucose values (75 g OGTT cut-off values of 5.1, 8.9, and 7.8 mmol/L) improved the detection rate (53%, 95% confidence interval 41% to 64%) and negative predictive value (0.94, 0.91 to 0.95), but decreased the specificity (0.91, 0.88 to 0.93) and positive predictive value (0.42, 0.32 to 0.53) at a false positive rate of 9% (positive likelihood ratio 5.59, 4.0 to 7.81; negative likelihood ratio 0.64, 0.52 to 0.77; and diagnostic odds ratio 10.07, 6.26 to 18.31).

Conclusions

The results of this prospective low risk cohort study indicated that the 75 g OGTT as a screening tool in early pregnancy is not sensitive enough when applying WHO 2013 criteria. Postload glucose values were higher in early pregnancy complicated by diabetes in pregnancy. Lowering the postload cut-off values identified a high risk group for later development of gestational diabetes mellitus or those who might benefit from earlier treatment. Results from randomised controlled trials showing a beneficial effect of early intervention are unclear.

Trial registration

ClinicalTrials.gov NCT02035059.

Screening of GDM during COVID pandemic in an Italian setting: comparison between IADPSG and WHO '99 criteria

BACKGROUND

During pandemic period, a single fast glycemia value (≥ 92 mg/dl) performed within the recommended time window for the risk level defined by the Italian guidelines, was considered an acceptable surrogate for GDM diagnosis following Italian Diabetes Association recomendations.

METHODS

All pregnant women who performed an OGTT following Italian Guidelines from march 2020 to september 2021 and then delivered at our University Hospital were prospectively enrolled in this study. Primary outcome of the study was the number of women diagnosed with GDM with only the FPG value (≥ 92 mg/dl), following Italian Diabetes Societies recommendations for COVID 19 pandemic period. At the same time, the data of women who became diabetic according to the 1999 WHO criteria was collected too. The secondary outcome was the comparison of risk factors of women undergoing OGTT according to IADPSG and WHO'99 criteria for the diagnosis of GDM and associated clinical outcomes.

RESULTS

The number of women with a diagnosis of GDM following Italian guidelines in the 18-month period considered was 161. Only 109 (67.7%) had a fast glucose value ≥ 92 mg/dl. No differences between IADPSG and WHO'99 groups in relation to risk factors, with the exception for overweight and obesity, and clinical outcomes.

CONCLUSION

Recommendations of Italian Diabetes Societis for COVID 19 pandemic failed to recognize one third of GDM diagnosis. Clinical Trial Registration ClinicalTrials.gov, www.

CLINICALTRIALS

gov , NCT05026840, August 30, 2021, 'retrospectively registered'.