The IFCC Reference Measurement System for HbA1c: A 6-Year Progress Report

Determination of [Glu1]-fibrinopeptide B purity by gas chromatography - isotope dilution mass spectrometry

The present work assessed the purity of [Glu1]-fibrinopeptide B (GFB) as a model peptide using gas chromatography - isotope dilution mass spectrometry. GFB and various isotope-labeled amino acids were hydrolyzed in HCl and then derivatized using optimized procedures. The primary impurity in GFB was also identified and used to correct the final result. A method repeatability of 0.5% was achieved and linear calibrations were obtained for five amino acids. The LOD and LOQ were 0.041 to 0.096 μg g-1, and 0.16 to 0.56 μg g-1, respectively. The purity of GFB was found to be (0.715 ± 0.012) g g-1. This technique exhibited comparable accuracy to that obtainable from liquid chromatography - isotope dilution mass spectrometry but at lower cost. This method could be employed as a reference technique or in fields such as clinical diagnostics or bio-pharmaceutical peptide purity analysis.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association for Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (HbA1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of HbA1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

BACKGROUND

Numerous laboratory tests are used in the diagnosis and management of diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for laboratory analysis in screening, diagnosis, or monitoring of diabetes. The overall quality of the evidence and the strength of the recommendations were evaluated. The draft consensus recommendations were evaluated by invited reviewers and presented for public comment. Suggestions were incorporated as deemed appropriate by the authors (see Acknowledgments). The guidelines were reviewed by the Evidence Based Laboratory Medicine Committee and the Board of Directors of the American Association of Clinical Chemistry and by the Professional Practice Committee of the American Diabetes Association.

CONTENT

Diabetes can be diagnosed by demonstrating increased concentrations of glucose in venous plasma or increased hemoglobin A1c (Hb A1c) in the blood. Glycemic control is monitored by the people with diabetes measuring their own blood glucose with meters and/or with continuous interstitial glucose monitoring (CGM) devices and also by laboratory analysis of Hb A1c. The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of ketones, autoantibodies, urine albumin, insulin, proinsulin, and C-peptide are addressed.

SUMMARY

The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are found to have minimal clinical value at the present time, and measurement of them is not recommended.

Protein glycation in diabetes mellitus

Diabetes mellitus is the ninth leading cause of mortality worldwide. It is a complex disease that manifests as chronic hyperglycemia. Glucose exposure causes biochemical changes at the proteome level as reflected in accumulation of glycated proteins. A prominent example is hemoglobin A1c (HbA1c), a glycated protein widely accepted as a diabetic indicator. Another emerging biomarker is glycated albumin which has demonstrated utility in situations where HbA1c cannot be used. Other proteins undergo glycation as well thus impacting cellular function, transport and immune response. Accordingly, these glycated counterparts may serve as predictors for diabetic complications and thus warrant further inquiry. Fortunately, modern proteomics has provided unique analytic capability to enable improved and more comprehensive exploration of glycating agents and glycated proteins. This review broadly covers topics from epidemiology of diabetes to modern analytical tools such as mass spectrometry to facilitate a better understanding of diabetes pathophysiology. This serves as an attempt to connect clinically relevant questions with findings of recent proteomic studies to suggest future avenues of diabetes research.

Type 1 diabetes in Laos, 2016-2021

OBJECTIVE

Before 2016, no child was known to survive type 1 diabetes (T1D) in Laos, a lower-middle income country (LMIC) in South-east Asia. In partnership with the Laos government, a non-government organization (NGO) called Action4Diabetes (A4D) has since been providing insulin, blood glucose monitoring kits, HbA1c testing, and emergency hospital expenses for Laotian children and young people (CYP) with T1D, and education for healthcare professionals. Here, we report the demographics and clinical outcomes of the CYP with T1D enrolled in A4D's Clinic Support Programme.

RESEARCH DESIGN AND METHODS

We collated and analyzed data on all known CYP with T1D in Laos, including gender, age and presentation at diagnosis, duration of diabetes, hospital admissions, and glycemic control during follow-up.

RESULTS

Fifty-three CYP (30 male; 57%) were diagnosed with T1D at a mean age of 11.3 years. Thirty CYP (57%) presented in diabetic ketoacidosis (DKA) at diagnosis. As at 16 August 2021, mean duration of T1D was 2.3 years. Forty-five CYP (85%) remained on active follow-up. Mean HbA1c for all 53 CYP was 8.7% (72 mmol/mol). Average HbA1c for the CYP in the age ranges of 1-5 years, 6-10 years, 11-15 years, 16-20 years, and 21-25 years, was 7.9% (63 mmol/mol), 8.2% (66), 8.4% (68), 9.4% (79), and 8.4% (68), respectively.

CONCLUSIONS

This is the first report on the status of T1D care in Laos, achieved through close partnership between the government and an NGO from 2016 to 2021. More global efforts to improve T1D care outcomes in Laos and other LMICs are urgently needed.

External quality assessment scheme for HbA1c assays in Thailand: A 5-year experience

Background

Thailand National External Quality Assessment Scheme (NEQAS) for HbA1c was established to evaluate the quality of HbA1c assays in Thailand in 2016.

Methods

HbA1c results from participating laboratories were compared to the target value assigned by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference system.

Results

The pass rates of participating laboratories during 2016–2020 were72–88%. The mean bias ranged between −0.19 and 0.20% of HbA1c. SD ranged from 0.30 to 1.08% of HbA1c. The overall coefficients of variation ranged from 4.46-15.66%.

Conclusions

Performance evaluation using IFCC assigned values indicated that different assay methods had an effect on HbA1c results. Participation in external quality assessment programs for HbA1c analysis is essential for improving laboratory quality and benefiting patient management.

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This study summarized the performance evaluation of HbA1c assays using IFCC assigned values during a 5 year period in Thailand.

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The most interesting finding was that the quality of HbA1c analysis varied depending on the assay method used.

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This finding should encourage clinical laboratories, manufacturers, and proficiency testing providers to work together to improve laboratory quality.

Employment status and diabetic outpatient appointment non-attendance in middle to senior working generation with type 2 diabetes: the Japan diabetes outcome intervention trial-2 large‑scale trial 005 (J-DOIT2-LT005)

AIMS

Workplace demands, support, and relationships differ according to employment status (e.g., employment that is full-time, part-time, or self-employed) and may lead to unequal opportunities to keep diabetic appointments. We investigated the association between employment status and outpatient diabetic appointment non-attendance among working-age adults with type 2 diabetes.

METHODS

This was a secondary analysis of a cluster-randomized trial (the Japan diabetes outcome intervention trial 2 large-scale trial). The analysis included 2010 trial participants (40-65 years old) with type 2 diabetes who were regularly followed by primary care physicians (PCPs). The outcome measure was the first non-attendance (defined as a failure to visit a PCP within 2 months of the original appointment) during the one-year follow-up. The association between baseline employment status and non-attendance was examined using Cox proportional hazard model in men and women.

RESULTS

During the 1279 and 789 person-year follow-up periods, 90 men and 34 women, respectively, experienced their first appointment non-attendance. Among men, self-employed participants had a higher risk of non-attendance compared with full-time employees (adjusted HR, 1.84; 95% CI, 1.15, 2.95). The trial intervention (attendance promotion) was associated with a significantly reduced risk of non-attendance among self-employed participants (HR, 0.51; 95% CI, 0.26, 0.99). Among women, a significant association between employment status and non-attendance was not observed.

CONCLUSIONS

Self-employed men with type 2 diabetes had a twofold increased risk of non-attendance than did full-time employees. Our study suggests that self-employed men with type 2 diabetes should be targeted for interventions promoting appointment adherence.

Predictive value of the glycated albumin versus glycosylated hemoglobin in follow-up of glucose homeostasis in hemodialysis-maintained type-2 diabetic patients

Objectives. Markers for glucose control in hemodialysis patients (HDP) are debated. Glycosylated hemoglobin (HbA1c%) relies on the stable red blood cell survival. Albumin turnover is faster than hemoglobin. Glycated albumin (GA%) may be used as an index of short-term glycemic control. The predictive value of GA% versus HbA1c% in monitoring the glucose homeostasis in type-2 diabetic HDP is studied. Methods. Forty type-2 diabetic HDP and 20 healthy non diabetic subjects matched age and sex as a control group were included. Calculation of body mass index and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and urea reduction ratio were done. Glycosylated hemoglobin, glycated albumin, fasting blood glucose, insulin, total lipid, kidney and liver functions tests, hepatitis markers, electrolytes, complete blood count, and international normalized ratio were performed. Patients were followed up after 6 months. Results. The study showed that GA% is more sensitive than HbA1c%, but less specific in the follow-up of the glucose homeostasis in type-2 diabetic HDP. Diagnostic accuracy is higher in HbA1c% than in GA%. HOMA-IR is superior regarding the sensitivity and the diagnostic accuracy. Conclusion. The present data show that GA% is more sensitive than HbA1c% and has more diagnostic accuracy in the follow-up of the glucose homeostasis in type-2 diabetic HDP.

Labile glycated hemoglobin: an underestimated laboratory marker of short term glycemia

OBJECTIVES

Diabetes mellitus is a major public health problem. Hemoglobin A_1c (HbA_1c) is a key laboratory parameter in the management of diabetes patients. However, in diabetes monitoring, interpretation of HbA_1c results is hampered by the important interindividual variation in red blood cell (RBC) life span. Furthermore, HbA_1c only slowly responds to changes in glucose metabolism. Besides HbA_1c, there exists a labile HbA_1c fraction (l-HbA_1c), exhibiting much faster kinetics. As both HbA_1c and l-HbA_1c are measured by modern standard chromatography, we explored the possibilities of using the l-HbA_1c fraction for monitoring glycemia.

METHODS

l-HbA_1c and HbA_1c fractions were simultaneously assayed on a Tosoh G8 analyzer and expressed as %. l-HbA_1c results were compared with serum glucose and HbA_1c. Concomitantly, RBC distribution width (RDW) was determined on a Sysmex SN analyzer as a marker for erythrocyte life span.

RESULTS

l-HbA_1c could be measured with between-run coefficient of variations (CVs) between 2.2 and 2.3%. l-HbA_1c correlated with both glycemia (r=0.80) and HbA_1c results (r=0.73). In a multiple regression model (r²=0.752), glycemia and HbA_1c were the most determining factors. To a lesser extent, RDW correlated with l-HbA_1c (r=0.158). Furthermore, the l-HbA_1c/HbA_1c ratio weakly positively correlated with RDW (r=0.247).

CONCLUSIONS

L-HBA_1c represents an additional marker for monitoring the rapid occurrence of glycemic disorders that escape detection when using only HbA_1c and blood glucose. RDW can be used as an indicator of atypical RBCs life span, in which the l-HbA_1c fraction may be helpful.

Compliance of the POCT method with the fully automated method for HbA1c determination

Previous research suggests that point-of-care (POCT) determination of glycated hemoglobin (HbA1c) is a diagnostic test that can be an adequate alternative to measuring HbA1c in the laboratory. The main goal of this study was to examine the analytical characteristics of the novel INCLIX POCT method for HbA1c determination in order to test its performance before introducing this method into routine use. HbA1c is measured in a duplicate in 44 EDTA blood samples parallel on INCLIX POCT device (Sugitech, Inc.) and using automated turbidimetric immunoinhibition test on Olympus AU400 (Beckman Coulter). The within run imprecision was 7.58%, between runs imprecision was 6.63% and 6.22%, and day-to-day imprecision was 8.80% and 7.51%. Total laboratory imprecision was in agreement with those stated by the manufacturer. A statistically significant Pearson correlation coefficient was calculated (r = 0.871, P < 0.01; linear R2 = 0.757). Using Deming regression analysis, the following equation was obtained: y = - 1.80 + 1.304x. Our results indicate statistically significant correlation, linear relationship, and a significant degree of compatibility between the two analyzed methods. However, the negative bias of the HbA1c values determined on the POCT analyzer compared to the Olympus AU400 was confirmed, highlighting the need to standardize the INCLIX method.

Effects of Low-Dose Atorvastatin on the Peripheral Blood Mononuclear Cell Secretion of Angiogenic Factors in Type 2 Diabetes

The aim of this study was to investigate the influence of statins on the secretion of angiogenesis mediators by the peripheral blood mononuclear cells (PBMCs) derived from patients suffering from type 2 diabetes. The study group comprised 30 participants and included: 10 statin-treated patients with diabetes, 10 statin-free diabetic subjects, and 10 statin-free non-diabetic individuals. PBMCs isolated from the blood were cultured in vitro in standard conditions and in an environment mimicking hyperglycemia. Culture supernatants were evaluated for VEGF, MCP-1, Il-10, and Il-12 by flow cytometry using commercial BD^TM. Cytometric Bead Array tests. The secretion of VEGF, MCP-1 and Il-12 by PBMCs, cultured both in standard and hyperglycemic conditions, was significantly lower in the statin-treated patients with type 2 diabetes in comparison with the statin-free diabetic patients. Conversely, the secretion of Il-10 was higher in the statin-treated than in the statin-free diabetic patients. VEGF, MCP-1 and Il-12 levels in PBMCs supernatants from the glucose-containing medium were higher than those from the standard medium in each of the diabetic groups. The results of the study suggest that statins in low doses exhibit an antiangiogenic activity, reducing the secretion of potent proangiogenic factors, such as VEGF and MCP-1, and increasing the secretion of antiangiogenic Il-10 by PBMCs, also under hyperglycemic conditions characteristic for type 2 diabetes.

Time in range correlates glycated albumin measured immediately after 2 weeks of continuous glucose monitoring

AIMS

Time in range (TIR), an index of glycemic control and also blood glucose fluctuation, obtained from continuous glucose monitoring (CGM), has been increasing its importance along with the spread of CGM in recent years. For a while, glycated albumin (GA) has been also used as a glycemic control index during about 2-weeks in routine clinical practice. It has not yet been confirmed under optimal condition whether TIR and GA correlates. Clarification of the correlation between TIR and GA, which was measured immediately after 2-weeks of CGM, might be a finding that further supports the utility of TIR.

METHODS

GA was measured at the conclusion of 2-week CGM in 71 diabetes outpatients at our hospital, and the correlation between GA and indices such as TIR obtained from CGM was statistically analyzed.

RESULTS

It was found that TIR and time above range (TAR) were significantly correlated with GA. Upon performing multiple regression analysis, TIR, TAR and BMI. indicated a significant regression coefficient with respect to GA.

CONCLUSIONS

These findings further support the utility of TIR as a marker of glycemic control that it might also be correlated with GA, and also suggest a relation between GA and blood glucose fluctuation.

Comparison of glycation degrees of HbG-Coushatta and HbG-Taipei with HbA using liquid chromatography with tandem mass spectrometry

BACKGROUND

Hemoglobin A_1c(HbA_1c) is widely used to measure glycemic status and control in diabetes testing and treatment and is an important risk factor forcomplications of diabetes. Hemoglobin variants can interfere with the HbA_1c testing method by reducing the life span of erythrocytes or due to differences in glycation degrees. In this study, glycation levels of the HbA, HbG-Coushatta, and HbG-Taipei β-chains (βA, βG-Coushatta, and βG-Taipei, respectively) were examined.

METHODS

Blood samples from heterozygotic patients (HbG-Coushatta/HbA, HbG-Taipei/HbA) were analyzed. Glycation rateswere determined using high-performance liquid chromatography with tandem mass spectrometry. Ratios of glycated βG-Coushatta to glycated βA and glycated βG-Taipei to glycated βA were calculated by comparingareas under the curves from extracted ion chromatograms.

RESULTS

βG-Coushatta and βG-Taipei were 6.08 ± 1.38% and 5.95 ± 0.93% glycated (respectively), which were significantly higher than βA chains(4.55 ± 1.30% and 4.51 ± 0.91%, respectively; p = 0.000). The total glycation degree (α + β) in HbG-Coushatta and HbG-Taipei heterozygotes were estimated to be 9% and 8% higher than those of HbA homozygotes (P＜0.001), respectively.

CONCLUSION

βG-Coushatta and βG-Taipei glycation degrees were significantly higher than βA, while the differences in total hemoglobin (α + β) were small and unlikely to impact the clinical interpretation of HbA_1c results.

Evaluation of the necessity and the feasibility of the standardization of procalcitonin measurements: Activities of IFCC WG-PCT with involvement of all stakeholders

Procalcitonin (PCT) is an important biomarker for sepsis diagnosis and management. To date, there is no higher-order reference measurement procedure (RMP) and certified reference material to achieve global standardization of results and results traceability to the SI units. Although efforts have been made to harmonize PCT results, a number of comparison studies and external quality assessment (EQA) schemes show conflicting results regarding results comparability and to date, equivalence of PCT results across the assays remains questionable in absence of studies relying on commutable EQA materials. In this context, the IFCC initiated activities to fill these gaps through the creation of the working group on standardization of PCT assays that gathers experts from National Metrology Institutes, calibration laboratories, clinicians, biologists, EQA providers and assay manufacturers. Among the activities, a higher order RMP and commutable reference materials are under development to build a robust reference measurement system (RMS). A commutability study is being organized to identify EQA materials that are fit for purpose to reliably estimate the current comparability of PCT results. This work will make it possible to evaluate the necessity and the feasibility for establishing and maintaining a new RMS for PCT assays, if deemed necessary.

Feasibility of procedures for a randomised pilot study of reduced exertion, high-intensity interval training (REHIT) with non-diabetic hyperglycaemia patients

Background

Physical activity and exercise interventions to improve health frequently bring about intended effects under ideal circumstances but often fail to demonstrate benefits in real-world contexts. The aim of this study was to describe the feasibility of an exercise intervention (reduced-exertion, high-intensity interval training) in non-diabetic hyperglycaemia patients delivered in a National Health Service setting to assess whether it would be appropriate to progress to a future large-scale study.

Methods

The intention was to recruit 40 participants from a single centre (specialist diabesity centre). Patients were eligible to take part if they were diagnostically defined as non-diabetic hyperglycaemic based on a glycated haemoglobin (HbA_1c) value of 42–46 mmol mol. Study procedures including recruitment, occurrence of adverse events, intervention acceptability, and intervention adherence were used to assess feasibility.

Results

Key criteria for progression to a larger study were not met. The study revealed several issues including patient eligibility, challenges to recruitment, patient consent, and poor clinician engagement. Furthermore, despite the simplicity and convenience of using HbA_1c to screen for diabetes risk, the process of accurately screening and case finding eligible patients was problematic. The small sample recruited for this trial (n = 6) also limits the interpretation of data, thus it is not possible to estimate the variability of intended outcomes to use in a formal sample size calculation for a full-scale trial. Some aspects of the intervention worked well. The acceptability of the exercise intervention and outcome measures met progression criteria thresholds and adherence was very high, with 97% of exercise sessions completed for participants that finished the study.

Conclusions

Given the issues, the trial is not feasible in its current form. Yet, this preparatory stage of trial design pre-empted problems with the intervention that could be changed to optimise the design and conduct of future studies. Solutions to the issues identified in this study revolve around using a dedicated local recruiter with a strong relationship among the healthcare team and patients, using participant incentives to take part, and allowing for a longer recruitment period.

Trial registration

ClinicalTrials.gov, NCT04011397. Registered 07 July 2019—retrospectively registered.

HYPOTHYROIDISM COULD BE A POTENTIAL FACTOR TO PROLONG SUBCUTANEOUS NODULES OF EXENATIDE ONCE WEEKLY: A CASE REPORT

Objective

Exenatide once weekly (ExeOW) is one of the long-acting glucagon-like peptide 1 receptor agonists. Embedding exenatide in poly(D,L-lactide-co-glycolide) microspheres enables the once-weekly subcutaneous injection of exenatide as a treatment for diabetes. We report a case of a patient with type 2 diabetes and hypothyroidism who developed long-standing subcutaneous nodules after treatment by ExeOW injection.

Methods

Case report and review of the literature. A 57-year-old Japanese man with type 2 diabetes treated with ExeOW and primary hypothyroidism.

Results

We observed multiple subcutaneous nodules remaining at the ExeOW injection site for >10 weeks. As the patient's thyroid hormone levels normalized, these nodules decreased and disappeared, and his hemoglobin A1c levels improved.

Conclusion

The patient's clinical course suggests that the hydrolysis of ExeOW at the site of injection may be inhibited by concomitant hypothyroidism, in which glycosaminoglycans including hyaluronic acid are known to accumulate (including in the skin). This case may indicate that hypothyroidism prolongs the existence of subcutaneous nodules from ExeOW treatment.

The global impact of the International Federation of Clinical Chemistry and Laboratory Medicine, Education and Management Division: engaging stakeholders and assessing HbA1c quality in a multicentre study across China

Background Diabetes mellitus is a major global issue and high quality testing is essential for the diagnosis and treatment of the disease. The IFCC Committee for the Education in the Utility of Biomarkers in Diabetes (C-EUBD) plays a global role in improving knowledge and understanding around diabetes testing. This paper describes a multi-stakeholder approach, to improving diagnostic and therapeutic testing for diabetes, using a multicentre study in China as an example of the global impact of the group. Methods Educational workshops were developed to support the scientific aims of the study in which 30 centres around China received identical, fresh frozen whole blood samples with values assigned using IFCC secondary reference methods and undertook precision (EP-5) and trueness studies. Performance was assessed using sigma metrics. Results A successful multi-stakeholder group was developed and sustained throughout the study through several educational workshops, which enabled the formation of a long-term collaboration with key opinion leaders and policy makers in China. All 30 centres showed good performance with within and between laboratory coefficient of variations (CVs) below 3% in SI units at both low and high haemoglobin A1c (HbA1c) levels. All individual laboratories met the criteria of a sigma of two or more at a total allowable error (TAE) of 5 mmol/mol (0.46% NGSP). Conclusions The study led to a successful multi-partner approach to improving diabetes testing in China. All centres involved in the study meeting the published IFCC quality criteria, paving the way for future clinical trials and an expanded role for HbA1c testing across the country.

Impact of elevated HbA1c on long-term mortality in patients presenting with acute myocardial infarction in daily clinical practice: insights from a 'real world' prospective registry of the Zwolle Myocardial Infarction Study Group

BACKGROUND

Long-term clinical outcome is less well known in up to presentation persons unknown with diabetes mellitus who present with acute myocardial infarction and elevated glycosylated haemoglobin (HbA1c) levels on admission. We aimed to study the prognostic impact of deranged HbA1c at presentation on long-term mortality in patients not known with diabetes, presenting with acute myocardial infarction.

METHODS

A single-centre, large, prospective observational study in patients with and without known diabetes admitted to our hospital for ST-segment elevation myocardial infarction (STEMI) and non-STEMI. Newly diagnosed diabetes mellitus was defined as HbA1c of 48 mmol/l or greater and pre-diabetes mellitus was defined as HbA1c between 39 and 47 mmol/l. The primary endpoint was all-cause mortality at short (30 days) and long-term (median 52 months) follow-up.

RESULTS

Out of 7900 acute myocardial infarction patients studied, 1314 patients (17%) were known diabetes patients. Of the 6586 patients without known diabetes, 3977 (60%) had no diabetes, 2259 (34%) had pre-diabetes and 350 (5%) had newly diagnosed diabetes based on HbA1c on admission. Both short-term (3.9% vs. 7.4% vs. 6.0%, p<0.001) and long-term mortality (19% vs. 26% vs. 35%, p<0.001) for both pre-diabetes patients as well as newly diagnosed diabetes patients was poor and comparable to known diabetes patients. After multivariate analysis, newly diagnosed diabetes was independently associated with long-term mortality (hazard ratio 1.72, 95% confidence interval 1.27-2.34, P=0.001).

CONCLUSIONS

In the largest study to date, newly diagnosed or pre-diabetes was present in 33% of acute myocardial infarction patients and was associated with poor long-term clinical outcome. Newly diagnosed diabetes (HbA1c ⩾48 mmol/mol) is an independent predictor of long-term mortality. More attention to early detection of diabetic status and initiation of blood glucose-lowering treatment is necessary.

Update on biomarkers of glycemic control

Attaining and maintaining good glycemic control is a cornerstone of diabetes care. The monitoring of glycemic control is currently based on the self-monitoring of blood glucose (SMBG) and laboratory testing for hemoglobin A1c (HbA1c), which is a surrogate biochemical marker of the average glycemia level over the previous 2-3 mo period. Although hyperglycemia is a key biochemical feature of diabetes, both the level of and exposure to high glucose, as well as glycemic variability, contribute to the pathogenesis of diabetic complications and follow different patterns in type 1 and type 2 diabetes. HbA1c provides a valuable, standardized and evidence-based parameter that is relevant for clinical decision making, but several biological and analytical confounders limit its accuracy in reflecting true glycemia. It has become apparent in recent years that other glycated proteins such as fructosamine, glycated albumin, and the nutritional monosaccharide 1,5-anhydroglucitol, as well as integrated measures from direct glucose testing by an SMBG/continuous glucose monitoring system, may provide valuable complementary data, particularly in circumstances when HbA1c results may be unreliable or are insufficient to assess the risk of adverse outcomes. Long-term associations of these alternative biomarkers of glycemia with the risk of complications need to be investigated in order to provide clinically relevant cut-off values and to validate their utility in diverse populations of diabetes patients.

Development of the Metabolic Syndrome: Study Design and Baseline Data of the Lufthansa Prevention Study (LUPS), A Prospective Observational Cohort Survey

The Lufthansa Prevention Study (LUPS) study is a prospective observation of a healthy worker cohort to identify early changes in metabolism leading to the Metabolic Syndrome (MetS) and to analyze their relation to behavioral factors like nutrition, physical activity, psychological status, and to underlying genetic conditions. The LUPS study recruited a sample of 1.962 non-diabetic healthy adults between 25-60 years, employed at a flight base of Lufthansa Technik GmbH in Hamburg, Germany. Baseline assessments included anthropometric measures, blood and urine samples and medical history. Psychosocial variables, dietary habits and life-style risk factors were assessed via self-reported questionnaires.In this report we describe the study design and present baseline parameters including the prevalence of the MetS using different classification criteria. The MetS was present in 20% of male and 12% of female subjects according to the 'Harmonizing the metabolic syndrome' definition. The prevalence varies between 2.6% in male and 2.3% in female subjects up to 48% in male and 41% in female subjects according to different classification criteria of MetS.In conclusion, this first cross-sectional view on the LUPS data confirms the expectation that this cohort is rather healthy and thus provides the opportunity to analyze early changes associated with the development of the MetS. The LUPS study is registered as a clinical trial NCT01313156.

A Rapid Test Strip for Diagnosing Glycosylated Hemoglobin (HbA1c) Based on Fluorescent Affinity Immunochromatography

In this research, we developed a rapid and easy-to-operate point-of-care testing (POCT) strip based on fluorescent affinity immunochromatography to quantitatively determine HbA1c concentrations in whole blood. This assay, based on a sandwich method performed on test strips, effectively utilized the principle of an affinity chromatography column, which was commonly used in the detection of HbA1c, and the technology of traditional fluorescence immunochromatographic test strips (FICTS) were combined. In our test strips, the test line of traditional FICTS was transformed into the region of affinity chromatography, while improving the linearity and reducing the interference of the precursor of HbA1c and hemoglobin variants. The test strips could quantitatively detect HbA1c over a wide range (3 - 13.8%) with excellent linearity (R² > 0.99), and the assay accuracy was demonstrated by comparing with high-performance liquid chromatography (HPLC) (R² > 0.95). The simple, rapid, effective and quantitative strips will provide a novel method for the detection of HbA1c in clinical diagnosis.

Simvastatin attenuates the aberrant expression of angiogenic factors induced by glucose variability

AIM

Over the last few years, studies have indicated that fluctuant hyperglycemia is very likely to increase the risk of cardiovascular complications of diabetes. Statins are widely used in diabetes for the prevention of cardiovascular complications, but it is still not clear whether simvastatin could also prevent glycaemic variability - induced aberrant angiogenesis which plays a significant role in the development of atherosclerosis.

METHODS

Wistar rats were divided into four groups: (1) simvastatin-treated (20 mg/kg for 8 consecutive weeks) type 2 diabetes rat model with daily glucose excursions, (2) placebo-treated type 2 diabetes rat model with daily glucose excursions, (3) placebo-treated stable well-controlled type 2 diabetes rat model and (4) placebo-treated non-diabetic rats. Daily glucose fluctuations and several angiogenic factors: cVEGF, mRNA VEGF, VEGF-R1, VEGF-R2, TGF-beta expression, circulating endothelial and progenitor endothelial cells were measured in all groups.

RESULTS

Simvastatin decreased several factors enhanced by glucose excursions: circulating VEGF, mRNA TGF-beta expression in the myocardium and mRNA VEGFR-2 expression in the aorta. Simvastatin increased some factors attenuated by glucose fluctuations: mRNA VEGF expression and mRNA VEGFR-1 expression in the myocardium and in the aorta. In the simvastatin-treated group with glycaemic variability, the percentage of circulating endothelial cells was lower and the percentage of progenitor endothelial cells in peripheral blood was higher than in the placebo-treated rats with glucose-fluctuations.

CONCLUSIONS

Simvastatin used in the rat model of type 2 diabetes with glucose variability reduces glucose variability and limits glucose fluctuations-induced changes in the expression of angiogenic factors in the cardiovascular system.

EurA1c: The European HbA1c Trial to Investigate the Performance of HbA1c Assays in 2166 Laboratories across 17 Countries and 24 Manufacturers by Use of the IFCC Model for Quality Targets

BACKGROUND

A major objective of the IFCC Committee on Education and Use of Biomarkers in Diabetes is to generate awareness and improvement of HbA1c assays through evaluation of the performance by countries and manufacturers.

METHODS

Fresh whole blood and lyophilized hemolysate specimens manufactured from the same pool were used by 17 external quality assessment organizers to evaluate analytical performance of 2166 laboratories. Results were evaluated per country, per manufacturer, and per manufacturer and country combined according to criteria of the IFCC model for quality targets.

RESULTS

At the country level with fresh whole blood specimens, 6 countries met the IFCC criterion, 2 did not, and 2 were borderline. With lyophilized hemolysates, 5 countries met the criterion, 2 did not, and 3 were borderline. At the manufacturer level using fresh whole blood specimens, 13 manufacturers met the criterion, 8 did not, and 3 were borderline. Using lyophilized hemolysates, 7 manufacturers met the criterion, 6 did not, and 3 were borderline. In both country and manufacturer groups, the major contribution to total error derived from between-laboratory variation. There were no substantial differences in performance between groups using fresh whole blood or lyophilized hemolysate samples.

CONCLUSIONS

The state of the art is that 1 of 20 laboratories does not meet the IFCC criterion, but there are substantial differences between country and between manufacturer groups. Efforts to further improve quality should focus on reducing between-laboratory variation. With some limitations, fresh whole blood and well-defined lyophilized specimens are suitable for purpose.

HbA1c method performance: The great success story of global standardization

Diagnosing and monitoring the treatment of people with diabetes is a global issue and uses considerable resources in laboratories and clinics worldwide. Hemoglobin A1c (HbA1c) has been the mainstay of monitoring glycemic control in people with diabetes for many years and more recently it has been advocated as a diagnostic tool for type 2 diabetes mellitus (T2DM). Good analytical performance is key to the successful use of any laboratory test, but is critical when using the test to diagnose disease, especially when the potential number of diagnoses could exceed 500 million people. Very small variations in bias or increased imprecision could lead to either a missed diagnosis or overdiagnosis of the disease and given the scale of the global disease burden, this could mean erroneous categorization of potentially millions of people. Fundamental to good performance of diagnostic testing is standardization, with defined reference materials and measurement procedures. In this review, we discuss the historical steps to first harmonize HbA1c testing, followed by the global standardization efforts and provide an update on the current situation and future goals for HbA1c testing.

Accuracy of HbA1c as Monitored by External Quality Assessment and Compared With Patient Mean Values

BACKGROUND

The accuracy and trueness of results from a laboratory test, such as the HbA1c test, should not be taken for granted but must be checked continuously. A tool for this is the participation in external quality assessment (EQA) for all laboratories performing the HbA1c-test. An additional possibility to detect changes in trueness is to monitor variations in patient cohort mean or median values that is not explained by changes in treatment or selection of patients.

METHODS

Results reported to an EQA scheme for HbA1c during 20 years have been extracted from Equalis database. The results are compared to current analytical performance specifications (APS) and to the mean HbA1c levels for the Swedish population of persons with type 2 diabetes.

RESULTS

The accuracy of the HbA1c test has improved during the period. The hospital lab methods used in Sweden now fulfil APS agreed by professional organizations in Sweden. The accuracy for point-of-care tests (POCT) methods vary over time and fulfil APS for some periods. The bias found for some of the methods might explain changes seen in patient mean values for HbA1c in Sweden during the period 2007-2017.

CONCLUSIONS

The global standardization of HbA1c has resulted in an improved comparability for HbA1c-results worldwide. But even small variation in trueness for the methods in use might have important impact on mean HbA1c values for cohorts of patients. When a systematic error is observed for a specific method it is therefore essential that manufacturers correct the method without delay.

HbA1c levels in children with type 1 diabetes and correlation to diabetic retinopathy

BACKGROUND

Type 1 diabetes mellitus (T1D) is a metabolic disease causing hyperglycemia due to β-cell destruction. Despite adequate treatment, complications such as diabetic retinopathy (DR) are common. The first aim was to investigate if acute onset of type 1 diabetes differed between those who had developed retinopathy and who had not after 15 years from diagnosis. The second aim was to investigate if mean glycosylated hemoglobin (HbA1c) levels affect the time to development of DR.

METHODS

The medical records of all children and adolescents diagnosed with type 1 diabetes during 1993-2001 in our area in Sweden were studied retrospectively and the mean HbA1c each year until the development of retinopathy was investigated. In total 72 patients were included and the follow-up time was between 15 and 23 years. Gender, p-glucose, age and HbA1c at diagnosis were analyzed for possible correlations to years to retinopathy.

RESULTS

HbA1c was significantly higher among those who had developed DR after 15 years from diagnosis, 98±9.2 (n=25) vs. 86±9.2 (n=46; p=0.025). A negative correlation was found between age at diagnosis and years to DR (rs=-0.376; p=0.026). Mean HbA1c levels at years 6-10 after diabetes diagnosis correlated significantly (rs=-0.354, p=0.037) to years until retinopathy. Mean HbA1c levels at years 1-15 after diabetes diagnosis were significantly higher at years 2-3 and years 5-8 for those who had developed retinopathy after 15 years from diagnosis.

CONCLUSIONS

Higher HbA1c levels shortened the time to development of retinopathy. It is therefore important to keep HbA1c as close to normal as possible.

Difference of seasonal variation between glycated albumin and glycated haemoglobin

Background

Glycated albumin reflects 2–3-week glycaemic controls, and in addition to glycated haemoglobin, it has been used as a glycaemic control indicator. We presumed that glycated albumin also has seasonal variations and is related to temperature, similar to glycated haemoglobin.

Methods

The subjects were diabetic outpatients from April 2007 to March 2013. This resulted in the enrolment of 2246 subjects and the collection of a total of 53,968 measurements. Mean glycated haemoglobin, glycated albumin, and plasma glucose were calculated for each month over six years. The associations of the measures with each other and the average temperature for each month in Tokyo were assessed using Spearman rank correlation coefficients.

Results

Plasma glucose was highest in January and lowest in May. Glycated haemoglobin was highest in March and lowest in September. Glycated albumin was highest in May and lowest in December. Glycated albumin tended to have a disjunction with plasma glucose in winter. Glycated haemoglobin had seasonal variation, but glycated albumin did not. Plasma glucose and glycated haemoglobin showed significant negative correlations with temperature (rs = −0.359, P < 0.001, rs = −0.449, P < 0.001, respectively), but glycated albumin did not. However, glycated albumin was inter-correlated with plasma glucose (rs = 0.396, P < 0.001) and glycated haemoglobin (rs = 0.685, P < 0.001), and glycated haemoglobin was inter-correlated with plasma glucose (rs = 0.465, P < 0.001).

Conclusion

Glycated albumin and glycated haemoglobin showed different seasonal variations from each other over the six-year study period. Thus, further studies to identify factors that contribute to glycated albumin are needed.

New arguments for beneficial effects of alpha-lipoic acid on the cardiovascular system in the course of type 2 diabetes

PURPOSE

Alpha-lipoic acid (ALA), widely known as an antioxidant, modifies also serum levels of angiogenic factors in type 2 diabetic patients. These pharmacological activities may influence the status of the cardiovascular system. Taking into consideration that diabetes is related to the increased cardiovascular risk we investigated several effects of ALA on angiogenic factors in the myocardium and in the aortal wall using a rat model of type 2 diabetes.

METHODS

Diabetes was induced in Wistar rats by a fat-rich diet and by intraperitoneal injection of a small dose of streptozotocin (30 mg/kg). Animals were divided into 3 groups: ALA-treated type 2 diabetes rat model, placebo-treated type 2 diabetes rat model and placebo-treated non-diabetic rats. ALA was administered orally once a day, 20 mg/kg, for 8 consecutive weeks. mRNA VEGF, VEGF-R1 and VEGF-R2 expression was measured in the myocardium and the aortal wall, simultaneously with circulating VEGF and circulating endothelial cells (cEC) and endothelial progenitor cells (cEPC).

RESULTS

ALA induced pro-angiogenic effect in the myocardium of rats with diabetes increasing mRNA VEGF expression and decreasing mRNA VEGFR-1 expression, while in the aortal wall ALA increased mRNA VEGFR-2 and VEGFR-1 expression. cVEGF in the ALA-treated group was higher comparing to both control groups. It was revealed that cEC percentage in the ALA-treated group was decreased with no effect on the percentage of cEPC.

CONCLUSIONS

In summary, the current data provide novel findings about potential beneficial effects of ALA on angiogenic factors in the cardiovascular system, especially on myocardium, in the course of type 2 diabetes.

Clinical significance of serum complement factor 3 in patients with type 2 diabetes mellitus

AIMS

Although serum complement factor 3 (C3) is an acute phase reactant mainly synthesized in the liver, several recent studies have shown high C3 gene expression in adipose tissue (AT). However, the relationship between C3 and AT levels has not been fully clarified in type 2 diabetes mellitus (T2DM) patients.

METHODS

A total of 164 T2DM patients (109men and 55 women) participated in this cross-sectional study. A computed tomography scan was performed to measure visceral, subcutaneous, and total AT. The correlation between these factors and C3 levels was examined using Pearson's correlation analysis. A multivariate regression model was used to assess an independent determinant associated with C3 levels after adjusting the explanatory variables (i.e., all ATs [visceral, subcutaneous, and total], and clinical features [sex, age, body mass index, waist circumference, glycated hemoglobin, duration of diabetes, systolic blood pressure, diastolic blood pressure, aspartate aminotransferase levels, alanine aminotransferase levels, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, log(triglyceride levels), estimated glomerular filtration rate, and log(high-sensitivity C-reactive protein levels)]).

RESULTS

Serum C3 levels were correlated with visceral, subcutaneous, and total AT among both men (r=0.505, p<0.001; r=0.545, p<0.001; r=0.617, p<0.001, respectively) and women (r=0.396, p=0.003; r=0.517, p<0.001; r=0.548, p<0.001, respectively). In the multivariate regression model, the association between total AT and C3 levels remained significantly positive (β=0.490, p<0.001).

CONCLUSIONS

Serum C3 levels are associated with visceral, subcutaneous, and total AT in T2DM patients. Furthermore, C3 levels seem to be a marker for overall adiposity rather than regional adiposity.

Understanding the Use of Sigma Metrics in Hemoglobin A1c Analysis

This study uses three unique data sets to show the state of the art of hemoglobin A1c (HbA1c) analyzers in a range of settings and compares their performance against the international guidance set by the International Federation of Clinical Chemistry and Laboratory Medicine task force for HbA1c standardization. The data are used to show the effect of tightening those criteria, and the study serves as a guide to the practical implementation of the sigma-metrics approach in a range of clinical settings.

Relationship between HbA1c and cancer in people with or without diabetes: a systematic review

AIM

To identify the relationship between HbA1c and cancers in people with or without diabetes.

BACKGROUND

Cancer is a major public health problem, accounting for 8.2 million deaths worldwide in 2012. HbA1c level has been associated with the risk of developing certain cancers, although the existing evidence is conflicting.

METHODS

EMBASE, MEDLINE, CINAHL and the Cochrane Library were searched. Eligible articles included randomized controlled trials, cohort studies, case-control studies, systematic reviews and meta-analyses. Participants of either sex, with or without Type 1 or 2 diabetes, were included. The studies were assessed using the Scottish Intercollegiate Guidelines Network (SIGN) criteria by two independent assessors. No meta-analysis was performed because of the heterogeneity of results.

RESULTS

A total of 19 studies from 1006 met the inclusion criteria, of which 14 were cohort studies and five were nested case-control studies. Eight studies investigated outcomes for all cancer sites. Four of these studies reported that higher HbA1c levels were associated with higher incidence and/or mortality risk for all cancers. One study observed a U-shaped relationship between HbA1c and cancer incidence and mortality. Increasing HbA1c levels were associated with increasing risk of developing colorectal, pancreatic, respiratory and female genital tract cancers. No increased risk was observed for breast cancer, gastrointestinal or urological malignancies.

CONCLUSION

HbA1c appears to be associated with cancer incidence and/or cancer mortality, but further studies are needed to fully understand the complex relationship between HbA1c and cancer.

Diabetes education for Chinese adults with type 2 diabetes: A systematic review and meta-analysis of the effect on glycemic control

AIMS

The purpose of this study is to systematically review evidence in English and Chinese publications to determine the size of glycemic effect of different diabetes education approaches for Chinese patients.

METHODS

CINAHL Plus, Embase, Ovid Medline, Scopus and the China National Knowledge Infrastructure database were searched. Studies were included if they were randomised controlled trials with a detailed description of education approach, with more than 50 Chinese-adult participants, reporting actual glycemic outcome and with at least 3-month follow-up. Data was systematically extracted and cross-checked by the authors. Methodological quality was assessed.

RESULTS

Fifty-three studies, including five English and 48 Chinese publications, were included. The overall weighted mean difference (WMD) in glycated haemoglobin (HbA1c) was -1.19% (-13mmol/mol). Ongoing regular education was most-commonly employed, with a reported WMD of -2.02% (-22mmol/mol). Glycemic control was further enhanced in studies using information reinforcement strategies.

CONCLUSIONS

Diabetes education in any format generates glycemic improvement for Chinese patients, but is particularly effective when an ongoing regular education is employed. Innovative strategies aligned with cultural concepts, such as employing patient examination to reinforce diabetes management knowledge and/or involving family in patient care deserve further trial to determine whether they enhance glycemic control in this group.

Quality of HbA1c Measurement in Trinidad and Tobago

BACKGROUND

Monitoring of HbA1c is the standard of care to assess diabetes control. In Trinidad & Tobago (T&T) there are no existing data on the quality of HbA1c measurement. Our study examined the precision and accuracy of HbA1c testing in T&T.

METHODS

Sets of 10 samples containing blinded duplicates were shipped to laboratories in T&T. This exercise was repeated 6 months later. Precision and accuracy were estimated for each laboratory/method.

RESULTS

T&T methods included immunoassay, capillary electrophoresis, and boronate affinity binding. Most, but not all, laboratories demonstrated acceptable precision and accuracy.

CONCLUSIONS

Continuous oversight of HbA1c testing (eg, through proficiency testing) in T&T is recommended. These results highlight the lack of oversight of HbA1c testing in some developing countries.

A Simple and Easy Process for the Determination of Estimated Plasma Glucose Level in Patients Presenting to Hospital: An Example of Multicentric Data Mining

The aim of the present study was to determine the relation between the simultaneous fasting plasma glucose level and HbA1c in a large population of patients presenting to the hospital, based on various measurement methods available for HbA1c. HbA1c levels of 162,210 patients presenting to various hospitals and laboratories were measured based on seven different systems, and at the same time, eAG levels were calculated based on HbA1c levels. The correlation coefficients (r) between serum plasma glucose and HbA1c levels were found to be 0.809, 0.774, 0.779, 0.817, 0.704, 0.796, and 0.747 in Bio-Rad Variant II, Tosoh G8, ADAMS A1c, Trinity Boronate Affinity, Chromsystems HPLC, Roche Tina-quant, and Abbott Architect, respectively. The concordance correlation coefficients between the eAG levels as calculated with the formulas provided in the text and the eAG levels as calculated according to NGSP directions (where eAG = (28.7*HbA1c) - 46.7) were found to be between 0.9339 and 0.9866. Despite the progress made for the standardization of HbA1c measurements, the relation between serum glucose and HbA1c still demonstrated certain discrepancies pertaining to the differences in measurement methodologies. As a conclusion, each laboratory could determine different eAG levels depending on the data originated by their individual analyzer.

Modified HPLC-ESI-MS Method for Glycated Hemoglobin Quantification Based on the IFCC Reference Measurement Procedure and Its Application for Quantitative Analyses in Clinical Laboratories of China

BACKGROUND

The level of glycated hemoglobin (HbA1c ) has been recognized as an important indicator of long-term glycemic control. However, the HbA1c measurement is not currently included as a diagnostic determinant in China. Current study aims to assess a candidate modified International Federation of Clinical Chemistry reference method for the forthcoming standardization of HbA1c measurements in China.

METHODS

The HbA1c concentration was measured using a modified high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) method. The modified method replaces the propylcyanide column with a C18 reversed-phase column, which has a lower cost and is more commonly used in China, and uses 0.1% (26.5 mmol/l) formic acid instead of trifluoroacetic acid. Moreover, in order to minimize matrix interference and reduce the running time, a solid-phase extraction was employed. The discrepancies between HbA1c measurements using conventional methods and the HPLC-ESI-MS method were clarified in clinical samples from healthy people and diabetic patients. Corresponding samples were distributed to 89 hospitals in Beijing for external quality assessment.

RESULTS

The linearity, reliability, and accuracy of the modified HPLC-ESI-MS method with a shortened running time of 6 min were successfully validated. Out of 89 hospitals evaluated, the relative biases of HbA1c concentrations were < 8% for 74 hospitals and < 5% for 60 hospitals. Compared with other conventional methods, HbA1c concentrations determined by HPLC methods were similar to the values obtained from the current HPLC-ESI-MS method.

CONCLUSION

The HPLC-ESI-MS method represents an improvement over existing methods and provides a simple, stable, and rapid HbA1c measurement with strong signal intensities and reduced ion suppression.

Thymic emigration patterns in patients with type 2 diabetes treated with metformin

Recent data suggest that thymic output, which provides the naive T cells necessary for the normal functioning of T-cell-dependent immunosurveillance cellular immunity including anti-cancer protection, can be disturbed in the course of type 2 diabetes. Metformin, an anti-diabetic drug commonly confirmed as an agent with many potential anti-cancer activities, might be helpful in this immune correction. The profile of thymic output was evaluated in the current study on the basis of the signal-joint T-cell receptor excision circle (sjTREC) concentration in peripheral blood polymorphonuclear cells and thymic emigrant content in peripheral blood evaluated from CD127 and/or CD132 antigen expression. It was revealed that recent thymic emigrants and more differentiated CD127(+) CD132(+) cell populations were decreased among naive T cells and CD8(+) T cells, whereas RTE count was increased in CD4(+) T cells, and the CD127(+) CD132(+) cell population was less numerous than in non-diabetic participants. Terminally differentiated thymic emigrants, i.e. CD127(-) CD132(+) cells, were increased in naive T cells and in CD8(+) T cells. Metformin affects mainly the early phases of thymic export, increasing CD127(+) CD132(-) and CD127(+) CD132(+) cell populations in naive T cells and the CD127(+) CD132(-) population in CD4(+) T lymphocytes. It could be concluded that type 2 diabetes deteriorates thymic immunostasis. The decreased thymic output could be compensated by metformin, especially with regard to CD4(+) naive T cells. It is the first time that therapy with metformin has been documented by us as particularly useful in the control and normalization of thymus function, regarding correction of early populations of thymic emigrants.

Marked increase in rat red blood cell membrane protein glycosylation by one-month treatment with a cafeteria diet

Background and Objectives. Glucose, an aldose, spontaneously reacts with protein amino acids yielding glycosylated proteins. The compounds may reorganize to produce advanced glycosylation products, which regulatory importance is increasingly being recognized. Protein glycosylation is produced without the direct intervention of enzymes and results in the loss of function. Glycosylated plasma albumin, and glycosylated haemoglobin are currently used as index of mean plasma glucose levels, since higher glucose availability results in higher glycosylation rates. In this study we intended to detect the early changes in blood protein glycosylation elicited by an obesogenic diet. Experimental Design. Since albumin is in constant direct contact with plasma glucose, as are the red blood cell (RBC) membranes, we analyzed their degree or glycosylation in female and male rats, either fed a standard diet or subjected to a hyper-energetic self-selected cafeteria diet for 30 days. This model produces a small increase in basal glycaemia and a significant increase in body fat, leaving the animals in the initial stages of development of metabolic syndrome. We also measured the degree of glycosylation of hemoglobin, and the concentration of glucose in contact with this protein, that within the RBC. Glycosylation was measured by colorimetric estimation of the hydroxymethylfurfural liberated from glycosyl residues by incubation with oxalate. Results. Plasma glucose was higher in cafeteria diet and in male rats, both independent effects. However, there were no significant differences induced by sex or diet in either hemoglobin or plasma proteins. Purified RBC membranes showed a marked effect of diet: higher glycosylation in cafeteria rats, which was more marked in females (not in controls). In any case, the number of glycosyl residues per molecule were higher in hemoglobin than in plasma proteins (after correction for molecular weight). The detected levels of glucose in RBC were lower than those of plasma, even when expressed in molal units, and were practically nil in cafeteria-diet fed rats compared with controls; there was no effect of sex. Conclusions. RBC membrane glycosylation is a sensitive indicator of developing metabolic syndrome-related hyperglycemia, more sensitive than the general measurement of plasma or RBC protein glycosylation. The extensive glycosylation of blood proteins does not seem to be markedly affected by sex; and could be hardly justified from an assumedly sustained plasma hyperglycemia. The low levels of glucose found within RBC, especially in rats under the cafeteria diet, could hardly justify the extensive glycosylation of hemoglobin and the lack of differences with controls, which contained sizeable levels of intracellular glucose. Additional studies are needed to study the dynamics of glucose in vivo in the RBC to understand how such extensive protein glycosylation could take place.

The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review

AIMS/HYPOTHESIS

The use of HbA1c for the diagnosis of diabetes is now widely advocated despite caveats to its use. Anaemia is cited as a major confounder to this use; however, the effect of erythrocyte indices and to what degree anaemia influences HbA1c levels is not known.

METHODS

A systematic electronic database search of MEDLINE, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL) and the Cochrane Library was conducted for relevant articles published between January 1990 and May 2014. Included studies had at least one measurement of HbA1c and glucose, and a least one index of haematinic deficiency, involving non-pregnant adults, not known to have diabetes.

RESULTS

A total of 12 articles from 544 were included. The majority of studies focused on iron deficiency anaemia (IDA) and, in general, demonstrated that the presence of iron deficiency with or without anaemia led to an increase in HbA1c values compared with controls, with no concomitant rise in glucose indices. Data on the effects of other indices of erythrocyte abnormalities on HbA1c are limited but show a possible decrease in HbA1c values with non-iron deficiency forms of anaemia.

CONCLUSIONS/INTERPRETATION

HbA1c is likely to be affected by iron deficiency and IDA with a spurious increase in HbA1c values; conversely, non-IDA may lead to a decreased HbA1c value. This may lead to confusion when diagnosing diabetes using HbA1c. This review clearly identifies the need for more evidence, especially in identifying the types and degrees of anaemia likely to have significant impact on the reliability of HbA1c.