Clinical evaluation of the reference intervals for diabetes in Chinese geriatric population: a cross-sectional cohort study protocol

INTRODUCTION

Diabetes mellitus (DM) is an important health issue that affects the ageing population. China has the largest geriatric population and the largest number of diabetes cases in the world. This poses a significant challenge for healthcare providers and policymakers. Haemoglobin A1C (HbA1c), which is one of the diagnostic criteria for diabetes, is affected by many factors such as pregnancy, age, race and anaemia. Glycated albumin (GA) is not influenced by factors that affect HbA1c concentrations, although it has been used in the diagnosis of diabetes in a few people. The aim of this study protocol is to determine reference intervals (RIs) of HbA1c and GA for the diagnosis of older adults with diabetes in China and to assess the optimal cut-off values for these parameters from a health economic perspective.

METHODS AND ANALYSIS

This cross-sectional survey study will recruit 1278 community-dwelling older adults aged 60-89 in Chengdu City. The data collection process will involve a questionnaire survey, a comprehensive physical examination and the collection of blood samples for laboratory testing. Data analyses will be conducted on the pooled sample and stratified by gender, age or other demographic features if necessary. Rates will be compared using the χ2 test or Fisher test and receiver operating characteristic (ROC) curves will be used to identify the most effective threshold values for HbA1c and GA for diagnosing diabetes among older adults in China.

ETHICS AND DISSEMINATION

The study protocol was approved by the ethics review board of the Bioethics Subcommittee of West China Hospital, Sichuan University (Approval No. 1705 in 2022). The study's results will be disseminated through peer-reviewed journals and scientific conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2300070831.

Glycated serum proteins and albumin but not glycated albumin show negative correlation with BMI in an overweight/obese, diabetic population from the United States

BACKGROUND AND AIMS

Multiple previously published studies have shown a weak to medium, negative correlation between BMI and glycated albumin (GA). However, many of these studies were in populations with a narrow range of BMI. It is unknown whether this trend exists if a wider BMI range is used. This is an important question for proper interpretation of GA levels in obese populations.

MATERIALS AND METHODS

A retrospective analysis of clinical trial data (NCT02519309) was performed. After appropriate exclusions, 334 subjects remained. These included 73.7% with type 2 diabetes (T2D) diagnosis and 26.3% with prediabetes. BMI ranged from 24.8-86.9 kg/m2. Laboratory data were measured in a CLIA-certified laboratory using commercially available, automated methods.

RESULTS

No significant, negative correlation was seen between GA and BMI. However, individual components (glycated serum proteins and albumin) as well as the GA/HbA1c ratio show a weak, negative correlation with BMI for all subjects and those with T2D. The strongest negative correlation was with albumin. Examination by traditional BMI subgroups also showed statistically significant differences for those with T2D, but not for the prediabetic cohort. Correlations between BMI and C-reactive protein were similar in those with diabetes and prediabetes; however, correlation between BMI and insulin was stronger in those with diabetes.

CONCLUSION

Negative correlations between BMI and albumin or BMI and glycated serum proteins persist in diabetic populations that are obese and overweight, even when a statistically significant negative correlation is not observed between BMI and GA. Inflammation or insulin-mediated changes in protein synthesis could be contributors to these negative correlations, but BMI-related changes to the glomerulus could also affect clearance of albumin or glycated proteins and should be examined.

Intervalos de referência de parâmetros de creatinina e hemoglobina glicosilada para a população adulta brasileira

Objetivo: estimar intervalos de referência (IR) de creatinina e hemoglobina glicosilada (HbA1c) na população adulta brasileira. Métodos: estudo transversal, utilizando na base de dados Pesquisa Nacional de Saúde (PNS), entre 2014-2015, composta por 8.952 adultos. Para estabelecer IR, aplicaram-se critérios de exclusão, removeram-se outliers e foi feita estratificação. Após esses procedimentos, a amostra constitui-se de 2.723 adultos para HbA1c e de 2.738 adultos para creatinina. Avaliaram-se diferenças pelos testes Mann Withney e Kruskal Wallis (p≤0,05). Resultados: homens (IR 0,69-1,25; mediana 0,95 mg/dL) apresentaram maiores IR para creatinina que mulheres (IR 0,53-1,05; mediana 0,74 mg/dL) e tiveram maiores valores de limites inferiores (LI) e mediana de HbA1c (sexo masculino: IR: 4,55-5,97; mediana 5,3%; sexo feminino: IR 4,49-5,97; mediana 5,20%) (p ≤ 0,05). Nas mulheres, IR para creatinina foram mais elevados entre 45 a 59 anos (IR: 0,55-1,04; mediana 0,77 mg/dL) e a partir dos 60 anos (IR: 0,54-0,98; mediana 0,77 mg/dL (p ≤ 0,05). Para HbA1c, homens apresentaram IR mais elevados a partir de 60 anos (IR 4,65-6,07; mediana 5,44%) e mulheres a partir de 45 anos (45 a 59 anos: IR 4,61-6,05; mediana 5,40%; e 60 anos ou mais: IR 4,82-6,03; mediana 5,50%) (p ≤ 0,05). Para creatina, foram observados menores LI dos IR e mediana mais proeminente nos adultos de raça/cor branca (IR: 0,56-1,19; mediana 0,85%) em comparação com a parda (IR: 0,55-1,19; mediana 0,84%) (p ≤ 0,05). Conclusão: IR próprios possibilitam desvelar as condições de saúde dos adultos brasileiros e podem subsidiar a identificação adequada de doença renal crônica e diabetes.

Combining HbA1c and glycated albumin improves detection of dysglycaemia in mixed-ancestry South Africans

BACKGROUND

Combining HbA_1c with glycated albumin (GA) may improve detection of dysglycaemia. As BMI correlates positively with HbA_1c and negatively with GA, HbA_1c may be more effective in obese and GA in nonobese individuals.

METHODS

To relate these findings to Africans, we assessed in 1274 South Africans living in CapeTown (male 26%; age 48±16y; BMI 28.7 kg/m² (range 15.6-73.8); obesity 39.9% and no prior diabetes history) the: (1) correlation of BMI with HbA_1c and GA, (2) ability of HbA_1c and GA separately and jointly, to detect OGTT-diagnosed dysglycaemia (diabetes plus prediabetes). Data collection took place between 2014 and 2016 in the City of Cape Town. Dysglycaemia was diagnosed by glucose criteria for the OGTT. Youden index was used to optimize diagnostic thresholds for HbA_1c and GA.

FINDINGS

Normal glucose tolerance, prediabetes and diabetes occurred in 76%, 17% and 7%, respectively. BMI positively correlated with HbA_1c [r = 0·34 [95%CI: 0·29,0·39)] and negatively with GA [-0·08 (0·13,0·03)]. For HbA_1c the optimal threshold by Youden-index for dysglycaemia diagnosis was: 6·0% (95%CI: 5·8,6·2) and for GA: 13·44% (12·72,14·71). In the nonobese, obese and total cohort, HbA_1c-alone detected: 51% (42-60), 72% (65,78), 63% (57,68), respectively; GA-alone detected 55% (52% (46,63), 52% (44, 59) and 53% (47,53), respectively; whereas: HbA_1c+GA detected: 69% (60,76), 82% (75,87) and 76% (71, 81). Therefore, for the total cohort detection of dysglycaemia HbA_1c-alone vs HbA_1c+GA detected 63% (57,68) vs 76% (71,81).

INTERPRETATION

The opposite correlations of HbA_1c and GA with BMI have now been demonstrated in an African-based population. Improving detection of dysglycaemia by combining HbA_1c and GA has important implications for diabetes risk screening.

FUNDING

AES is supported by the intramural programs of the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of Minority Health and Health Disparities of the National Institutes of Health (NIH, Bethesda, Maryland, USA). DBS is supported by the intramural program of the Clinical Center of NIH. The South African Medical Research Council (SAMRC) funded the VMH study with funds from the National Treasury under its Economic Competitiveness and Support Package (MRC-RFA-UFSP-01-2013/VMH Study).

Analytical performances of a glycated albumin assay that is traceable to standard reference materials and reference range determination

BACKGROUND

Glycated albumin (GA) is an intermediate-term marker for monitoring glycemic control (preceding 2-3 weeks) in patients with diabetes mellitus. We evaluated the performance of Lucica Glycated Albumin-L, a new GA assay that is traceable to standard reference materials and determined the reference range in healthy subjects without diabetes.

METHODS

The performance and reference range studies were conducted in accordance with Clinical and Laboratory Standards Institute (CLSI) Guidelines. The traceability was established using reference material recommended by the Japan Society of Clinical Chemistry (JSCC).

RESULTS

The coefficient of variation (CV) of overall repeatability, within-laboratory precision, and overall reproducibility values of GA values were not more than 2.6%, 3.3%, and 1.6%, respectively, among laboratories. The GA values showed good linearity from 173 to 979 mmol/mol (9.4%-54.9%) across the assay range. The GA reference range in 262 healthy subjects was between 183 and 259 mmol/mol (9.9%-14.2%) while that of subjects with diabetes was 217-585 mmol/mol (11.8-32.6%). The reagent was stable for 2 months on the bench at room temperature. The limits of blank, detection, and qualification were 6.9, 7.9, and 9.7 μmol/L for GA concentration, and 3.8, 7.0, and 21.8 μmol/L for albumin concentration, respectively. Hemoglobin slightly affected the assay, while other classical interfering substances had no significant impact.

CONCLUSIONS

The present GA assay shows comparable performance to current clinical assays and could be used for intermediate-term monitoring of glycemic control in diabetes patients.

Glycated albumin in pregnancy: LC-MS/MS-based reference interval in healthy, nulliparous Scandinavian women and its diagnostic accuracy in gestational diabetes mellitus

Glycated albumin (GA) may be a useful biomarker of glycemia in pregnancy. The aim of this study was to establish the reference interval (RI) for GA, analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), in healthy, nulliparous pregnant women. In addition, we assessed the accuracy of GA and glycated hemoglobin A1c (HbA1c) in the diagnosis of gestational diabetes mellitus (GDM). Finally, we explored the prevalence of GDM in healthy nulliparas, comparing three diagnostic guidelines (WHO-1999, WHO-2013 and the Norwegian guideline). The study was carried out at Stavanger University Hospital, Norway, and included a study population of 147 pregnant nulliparous women. An oral glucose tolerance test (OGTT) was performed and used as the gold standard for GDM diagnosis. Blood samples for analysis of GA and HbA1c were collected at pregnancy week 24-28. A nonparametric approach was chosen for RI calculation, and receiver operating characteristic (ROC) curves were used to evaluate the diagnostic performance of GA and HbA1c. The established RI for GA in 121 pregnant women was 7.1-11.6%. The area under the ROC curves (AUCs) were 0.531 (GA) and 0.627 (HbA1c). According to the WHO-1999, WHO-2013 and the Norwegian guideline, respectively, 24 (16%), 36 (24%) and 21 (14%) women were diagnosed with GDM. Only nine women (6%) fulfilled the GDM-criteria of all guidelines. In conclusion, we established the first LC-MS/MS-based RI for GA in pregnant women. At pregnancy weeks 24-28, neither GA nor HbA1c discriminated between those with and without GDM. Different women were diagnosed with GDM using the three guidelines.

Glycated albumin as a biomarker for diagnosis of diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Glycated albumin (GA), the non-enzymatic glycation product of albumin in plasma, became a glycemic marker in the beginning of the 21st century. The assay is not affected by hemoglobin levels and reflects the glycemic status over a shorter period as compared to HbA1c measurements. Thus, GA may contributes as an intermediate glucose index in the current diabetes mellitus (DM) diagnostic system.

AIM

To search and summarize the available data on glycated albumin measurements required for the diagnosis of diabetes mellitus.

METHODS

Databases, including PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL), among others, were systematically searched. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was applied for the assessment of quality, and the bivariate model was used to pool the sensitivity and specificity. The hierarchical summary receiver operator characteristic curves (HSROC) model was utilized to estimate the summary receiver operating characteristics curve (SROC). Sensitivity analysis was performed to investigate the association of the study design and patient characteristics with the test accuracy and meta-regression to find the source of heterogeneity.

RESULTS

Three studies regarding gestational diabetes mellitus (GDM) and a meta-analysis of 16 non-GDM studies, comprising a total sample size of 12876, were included in the work. Results reveal that the average cut-off values of GA reported for the diagnosis of GDM diagnosis was much lower than those for non-GDM. For non-GDM cases, diagnosing DM with a circulating GA cut-off of 14.0% had a sensitivity of 0.766 (95%CI: 0.539, 0.901), specificity of 0.687 (95%CI: 0.364, 0.894), and area under the curve of 0.80 (95%CI: 0.76, 0.83) for the SROC. The estimated SROC at different GA cut-off values for non-GDM exhibited that the average location parameter lambda of 16 non-GDM studies was 2.354 (95%CI: 2.002, 2.707), and the scale parameter beta was -0.163 (95%CI: -0.614, 0.288). These non-GDM studies with various thresholds had substantial heterogeneity, which may be attributed to the type of DM, age, and body mass index as possible sources.

CONCLUSION

Glycated albumin in non-DM exhibits a moderate diagnostic accuracy. Further research on the diagnostic accuracy of GA for GDM and combinational measurements of GA and other assays is suggested.

Preliminary reference intervals of Glycated Albumin in healthy Caucasian pregnant women

BACKGROUND AND AIMS

Glycated albumin (GA) could represent a useful biomarker in pregnant women for diagnosing and monitoring gestational diabetes mellitus (GDM). The establishment of reference intervals (RI) is mandatory before assessing its clinical usefulness. The RIs of GA in healthy pregnant women are not well defined. The aim of the current study was to establish the RI in a cohort consisting of Caucasian pregnant women without overt diabetes mellitus or gestational diabetes mellitus.

METHODS

The study included 183 healthy pregnant women. GA was measured on plasma by an enzymatic method (quantILab Glycated Albumin, IL Werfen, Germany). The RI was calculated by the non-parametric and robust methods.

RESULTS

The RI of GA in the whole population was 10.16% (90%CI 9.60-10.70) and 15.44% (90%CI 14.90-16.90). GA levels decreased during pregnancy, with lower levels in the third trimester: 10.11 (90%CI 9.48-10.79) and 15.72 (90%CI 15.15-16.27) in the first trimester, 10.49 (90%CI 10.05-10.96) and 15.49 (90%CI 15.05-15.92) in the second trimester, 9.84 (90%CI 9.50-10.22) and 14.57 (90%CI 14.11-15.01) in the third trimester. Finally, a weak negative correlation was found between GA levels and body mass index.

CONCLUSION

This is the first study establishing the RIs of GA in Caucasian healthy pregnant women.