High-sensitivity C-reactive protein does not improve the differential diagnosis of HNF1A-MODY and familial young-onset type 2 diabetes: A grey zone analysis.

AIM: Low plasma levels of high-sensitivity C-reactive protein (hs-CRP) have been suggested to differentiate hepatocyte nuclear factor 1 alpha-maturity-onset diabetes of the young (HNF1A-MODY) from type 2 diabetes (T2D). Yet, differential diagnosis of HNF1A-MODY and familial young-onset type 2 diabetes (F-YT2D) remains a difficult challenge. Thus, this study assessed the added value of hs-CRP to distinguish between the two conditions. METHODS: This prospective multicentre study included 143 HNF1A-MODY patients, 310 patients with a clinical history suggestive of HNF1A-MODY, but not confirmed genetically (F-YT2D), and 215 patients with T2D. The ability of models, including clinical characteristics and hs-CRP to predict HNF1A-MODY was analyzed, using the area of the receiver operating characteristic (AUROC) curve, and a grey zone approach was used to evaluate these models in clinical practice. RESULTS: Median hs-CRP values were lower in HNF1A-MODY (0.25mg/L) than in F-YT2D (1.14mg/L) and T2D (1.70mg/L) patients. Clinical parameters were sufficient to differentiate HNF1A-MODY from classical T2D (AUROC: 0.99). AUROC analyses to distinguish HNF1A-MODY from F-YT2D were 0.82 for clinical features and 0.87 after including hs-CRP. For the grey zone analysis, the lower boundary was set to miss<1.5% of true positives in non-tested subjects, while the upper boundary was set to perform 50% of genetic tests in individuals with no HNF1A mutation. On comparing HNF1A-MODY with F-YT2D, 65% of patients were classified in between these categories - in the zone of diagnostic uncertainty - even after adding hs-CRP to clinical parameters. CONCLUSION: hs-CRP does not improve the differential diagnosis of HNF1A-MODY and F-YT2D.

Association of peripheral neuropathy with circulating advanced glycation end products, soluble receptor for advanced glycation end products and other risk factors in patients with type 2 diabetes.

BACKGROUND: The pathogenesis of diabetic peripheral neuropathy remains uncertain and nonenzymatic glycoxidation is one of the contributing mechanisms. The aim of this study was to assess the respective relationship of diabetic peripheral neuropathy with glycoxidation, compared with other identified risk factors, in patients with type 2 diabetes. METHODS: We included 198 patients with type 2 diabetes and high risk for vascular complications. Circulating concentrations of three advanced glycation end products (carboxymethyllysine, methyl-glyoxal-hydroimidazolone-1, pentosidine) and of their soluble receptor (sRAGE) were measured. Peripheral neuropathy was assessed by the neuropathy disability score and by the monofilament test and defined as either an abnormal monofilament test and/or a neuropathy disability score ≥6. Multivariate regression analyses were performed adjusting for potential confounding factors for neuropathy: age, gender, diabetes duration, current smoking, systolic blood pressure, waist circumference, height, peripheral arterial occlusive disease, glycated haemoglobin, estimated glomerular filtration rate and lipid profile. RESULTS: Prevalence of peripheral neuropathy was 20.7%. sRAGE and carboxymethyllysine were independently and positively associated with the presence of peripheral neuropathy. No significant association was found between peripheral neuropathy and methyl-glyoxal-hydroimidazolone-1 or pentosidine. Waist circumference, height and peripheral arterial occlusive disease were independently associated with peripheral neuropathy. CONCLUSIONS: Carboxymethyllysine and sRAGE were independently associated with peripheral neuropathy in patients with type 2 diabetes. Although the conclusions are limited by the absence of a healthy control population, this study confirms the relationship between advanced glycoxidation and diabetic peripheral neuropathy, independently of other risk factors.

[Screening and diagnosis of gestational diabetes. Evaluation of the methodological quality of the guidelines of the Haute Autorité de Santé, of the American Diabetes Association, and of the World Health Organisation]. / Dépistage et diagnostic du diabète gestationnel: évaluation de la qualité méthodologique des avis de la Haute autorité de santé, de l'American diabetes association et de l'Organisation mondiale de la santé

We critically appraised the methodological quality of the clinical practice guideline (CPG) published by the Haute autorité de santé (HAS) about screening and diagnosis of gestational diabetes, and we compared its quality with that of two other CPGs, i.e. that of the American diabetes association (ADA) and that of the World health organisation (WHO). According to the AGREE criteria, HAS and ADA have produced CPGs that have approximately got the same levels of quality. Both these CPGs obtain AGREE scores that are better than those of WHO. Although the CPG of the HAS suffers from a few methodological drawbacks, regarding more particularly stakeholder involvement (AGREE domain n degrees 2), applicability (AGREE domain n degrees 5) and editorial independence (AGREE domain n degrees 6), this CPG summarises, and allows to compare most, if not all, other CPGs available with each other, with their possible benefits or harms, which may be useful for professionals involved in the care of the patient.

[Propositions for the standardized expression of HbA 1c results]. / Propositions pour l'expression standardisée des résultats d'HbA 1c.

The 2007 international consensus about the standardization of HbA(1c) determination and expression of results is progressively implemented in most countries. In France, a common working group of the Société française de biologie clinique (SFBC) and the Société francophone de diabétologie (SFD) has expressed the following recommendations. HbA(1c) results are expressed in percentage of total hemoglobin and in mmol HbA(1c)/mol Hb, but are not converted into estimated average glucose. A table indicating the correspondence between HbA(1c) and estimated average glucose may be given with the results, subject to precautions of interpretation at the individual level.

[Interference of hemoglobin variants on glycated hemoglobin measurement using Architect ci8200 immunoassay (Abbott Diagnostics)]. / Immunodosage de l'hémoglobine glyquée sur ci8200 (Abbott Diagnostics) en présence d'hémoglobines anormales.

The objective of this study was to compare haemoglobin A(1c) (HbA(1c)) levels measured by the immunoturbidimetric assay on ci8200 Architect (Abbott Diagnostics) to those obtained by the high pressure liquid chromatography (HPLC) assay from Tosoh Bioscience. Firstly, we verified correlation between the two methods in 47 subjects without hemoglobin variants: the coefficient of correlation was 0.968 and the regression equation was as follows: y(Abbott) = 0.928x(Tosoh) - 0.081. We then measured HbA(1c) levels by both methods in blood samples of 23 patients with a structural hemoglobin variant (A/S, A/C or S/C). Analysis of these samples revealed significant discrepancies between results of both methods, as indicated by the higher mean value obtained by immunoturbidimetric assay when compared to HPLC assay (7.17 +/- 2.68% vs. 5.86 +/- 1.41%). Classification of patients according to the HAS (French Haute Autorité de Santé) recommendations HbA(1c) was not modified for 68% of patients with abnormal hemoglobin. However, in 32% of cases, discrepancies between the two methods may have clinical importance, which justifies the occurrence of an abnormal hemoglobin when the HbA(1c) assay is performed by the method immunoturbidimetry Abbott Diagnostics.

[Practice guidelines: let us sort them]. / Guides de pratique clinique: trions-les.

A growing number of clinical practice guidelines (CPG) is published. This is understandable because CPG are the corner stone in the evaluation of professional practices (EPP). One cannot deny that EPP is necessary. However, in order for the EPP to reach their objectives, which are to use our resources better and to improve health-care, CPG at our disposal should be of good quality, both in their form and in their content. This is not always the case. What is more, health-care professionals are often not properly trained to distinguish "good" from "not so good" CPG. In this context, the Société française de biologie clinique has created a working group on "CPG and Evidence-Based Laboratory Medicine (EBLM)". One of the main objectives of our group is to publish critical appraisals of CPG on a regular basis in the Annales de Biologie Clinique (ABC). Thus, the ABC will follow the example set by other medical journals, for example in France: Prescrire. We will more particularly appraise CPGs in relation with laboratory medicine. In this first article, we describe the methods that we will use in order to distinguish "good" from "not so good" CPG. Just like Prescrire as well as like many others, our first tool will be the AGREE instrument, which is quite consensual at an international level. The AGREE tool makes it possible to appraise quite easily, and in a reproducible way, the methodological quality of CPG. We also briefly discuss the more complicated methods that can be used to make judgments about the content of CPG, bearing in mind that equity, patients' autonomy, balancing risks and benefits, are the four universal principles of medical ethics, that is of good medicine, that is of EB(L)M.

[Hemoglobin A1C determination and hemoglobinopathies: problems and strategies]. / Dosage de l'hémoglobine A(1c) et hémoglobinopathies: problèmes posés et conduite à tenir.

The semiological value of hemoglobin A1c (HbA1c) as a retrospective and cumulative marker of glycemic balance in diabetic patients is greatly weakened in case of hemoglobinopathy. The presence of an abnormal hemoglobin raises methodological problems due to the interferences generated in most assay methods, but also alters the normal process of HbA glycation to HbA1c, and often induces a certain level of hemolysis, very variable and impossible to quantify. This paper reviews methodological and semiological problems related to the presence of abnormal hemoglobin species, and proposes a standardized strategy in case of hemoglobinopathies.

[Considerations on delocalized HbA1c assays]. / Réflexions sur les dosages délocalisés d'hémoglobine A1C.

Availability and knowledge of HbA(1c) value during consultation is an important feature for diabetologists, that permits a better adaptation of therapy and a better motivation of patients. This expectation explains the request for delocalized assays of HbA(1c), even though life prognosis is not affected, like in the other cases of point of care testing. One of the most frequent solutions is the use of immunological delocalized HbA(1c) assays. Technically, these methods have to meet the same criteria as those used in laboratories. They have to be standardized, and controlled according to the "Guide de Bonne Exécution des Analyses de Biologie Médicale" (GBEA) rules. Solutions chosen for delocalization must respect specific skills of clinicians and biologists and cope with cost limitations. This paper reviews rationales for delocalized HbA(1c) assays, steps of their implementation, and their use in practical routine, with a special emphasis given on the necessary complementarity between clinicians and biologists.

Multicenter evaluation of Tosoh glycohemoglobin analyzer.

BACKGROUND: We describe an Anglo-French evaluation of a new analyzer. METHODS: The Tosoh HLC-723 GHb V, A1c2.2 glycohemoglobin analyzer is an HPLC instrument with primary blood tube sampling, bar-code reading, cap piercing, and the ability to chromatographically separate labile hemoglobin A1c (HbA1c). We evaluated two analytical protocols, 2.2 and 3.0 min, and compared results for blood samples collected from diabetic and nondiabetic subjects with those obtained with Bio-Rad Diamat and Variant analyzers. RESULTS: Within- and between batch-imprecision (CVs) was <2% with linearity to at least 15.9% HbA1c. Although some hemoglobinopathies were detected in the 2. 2-min chromatography, clearer evidence of abnormality was visible in the 3.0-min version. Comparison with established methods showed good correlation (r = 0.993; n = 316 with Diamat; and r = 0.995; n = 133 with Variant) but highlighted calibration differences. CONCLUSIONS: The problems of manual blood sample preparation, labile HbA1c, and carbamylated hemoglobin interference associated with the older instruments have been eliminated in the new Tosoh analyzer. The 3. 0-min protocol is preferred for routine use.

HBA1c: clinical and biological agreement for standardization of assay methods. Report by the experts of ALFEDIAM (Association de Langue Française pour lEtude du Diabète et des Maladies Métabolique) and SFBC (Société Française de Biologie Clinique). / HbA1c: concertation clinico-biologique pour la standardisation des méthodes de dosage. Rapport des experts de l'ALFEDIAM et de la SFBC.

Glycohaemoglobin, and particularly haemoglobin A1c(HbA1c), assays have been used for many years to retrospectively evaluate the glycaemic control of diabetic patients. Cut-off values have been established for deciding treatment modifications. The techniques used in the laboratories however exhibit varying quality, and all of them are not yet standardized. The consequence is an under-utilization of this test, especially in non-hospital practice. In this context, working groups of Société Française de Biologie Clinique (SFBC), Association de Langue Française pour l'Etude du Diabète et des Maladies Métaboliques (ALFEDIAM) and Société Française d'Endocrinologie (SFE) have met together, in order to analyze the national status, and to propose practical recommendations for implementing a standardization process on the basis of international experiences. It is recommended to exclusively express results as HbA1c percentage, using methods standardized and certified by comparison to reference methods such as those using Diabetes Control and Complications Trial (DCCT) values. Simultaneously, contacts have been established with manufacturers, and the realisation of periodic quality control surveys was encouraged.

[Respective value of glycated hemoglobin and fructosamine assays in the care of diabetes mellitus]. / Intérêts respectifs des dosages d'hémoglobine glyquée et de fructosamines dans la surveillance du diabète sucré.

The monitoring of metabolic balance in diabetes mellitus involves the assay of cumulative markers of protein glycation. Glycated hemoglobin, particularly the major component HbA1c, and fructosamine, which reflects glycated plasma protein levels, are the most commonly used parameters. Nevertheless, their utilization is still under discussion with respect to methodologies used, as well as to their respective interest in clinical diabetology. This review shows current opinion concerning the analytical and physiopathological use of these biological indicators.

A sensitive time-resolved immunofluorometric assay for the measurement of apolipoprotein B in cerebrospinal fluid. Application to multiple sclerosis and other neurological diseases.

Although low density lipoprotein receptors have been described on oligodendrocytes, apolipoprotein B was thought to be absent or present in only very small amounts in cerebrospinal fluid (CSF). Several immunoassays have been used for the measurement of apolipoprotein B in serum. However, the majority of methods cannot be used to measure small amounts of apolipoprotein B in CSF. In this study, we describe a highly sensitive time resolved immunofluorometric assay (TR-IFMA) using europium as label (detection limit: 0.3 microgram/l). The reliability of the TR-IFMA for the measurement of apolipoprotein B was first studied in serum. Serum and CSF apolipoprotein B concentrations were then determined in subjects free of neurological disorders and in patients with multiple sclerosis. Local intrathecal apolipoprotein B synthesis was calculated. Although the high sensitivity of the TR-IFMA allowed low amounts of apolipoprotein B in CSF to be detected (0.11 +/- 0.06; 0.12 +/- 0.06 mg/l in controls and multiple sclerosis patients, respectively), no apolipoprotein B could be detected in CSF by electroimmunodiffusion. As suggested by the blood/CSF apolipoprotein B ratio (about 6000), no apolipoprotein B synthesis was observed by both using apolipoprotein B index and formula. This indicates its probable serum origin. Moreover, there was no difference between controls and multiple sclerosis patients in CSF, serum, blood/CSF, index, and local intrathecal apoliprotein B synthesis. Finally, these results suggest that the role of apolipoprotein B in lipid transport in the central nervous system may be questionable.

Application of the time-resolved immunofluorometric assay to the study of C3 complement component glycation in vitro and in vivo.

A time-resolved immunofluorometric assay (TR-IFMA) was used for the measurement of glycated C3. The very high sensitivity of this technique allowed the direct measurement of glycated and non-glycated proteins (especially C3) in chromatography eluates. C3 glycation in vitro after incubation with 20 mmol/l glucose was always less than 3.5% by day 5. As determined with the TR-IFMA, the means +/- standard deviations of glycated C3 were 0.20% +/- 0.04 for non-diabetic subjects and 0.88% +/- 0.06 for insulin-dependent diabetic patients. The low percentages of glycated C3 in both our in vitro and in vivo studies show that this protein is subject to only moderate rates of glycation.