[Glycohemoglobin (GHb): clinical and analytical aspects]

Predisposition to Type 2 Diabetes in Aspects of the Glycemic Curve and Glycated Hemoglobin in Healthy, Young Adults: A Cross-sectional Study

OBJECTIVES

Our aim in this study was to identify predictors for diabetes among the characteristics of the glycemic curve and glycated hemoglobin (A1C) in healthy, young adults.

METHODS

We used a cross-sectional study to establish predictors for diabetes based on earlier studies and evaluated occurrence of the condition in 81 healthy, young adult subjects. These volunteers underwent analysis of fasting plasma glucose, oral glucose tolerance test plasma glucose, A1C, and inflammatory markers (leukocytes, monocytes, and C-reactive protein). The nonparametric Mann-Whitney U test, Fisher's exact test, chi-square test, Kruskal-Wallis test, and multiple-comparisons test were used to analyze the data.

RESULTS

We studied 2 age groups, homogeneous in terms of family history of diabetes: one group ranged in age from ≥18 to <28 years (median 20 years; body mass index [BMI] 24 kg/m2) and the other group ranged in age from ≥28 to <45 years (median 35 years; BMI 24 kg/m2). The older group had a higher incidence of predictors (p=0.0005) and was associated with the predictors 30-minute blood glucose ≥164 mg/dL (p=0.0190), 60-minute blood glucose ≥125 mg/dL (p=0.0346), and A1C ≥5.5% (p=0.0162), with a monophasic glycemic curve (p=0.007). The younger group was associated with the 2-hour plasma glucose predictor ≥140 mg/dL (p=0.014). All subjects had fasting glucose in the normal range.

CONCLUSIONS

Healthy, young adults may already have predictors of diabetes, identified mainly by aspects of the glycemic curve and A1C, but at more modest levels than those with prediabetes.

Use of Machine Learning and Routine Laboratory Tests for Diabetes Mellitus Screening

Most patients with diabetes mellitus are asymptomatic, which leads to delayed and more complex treatment. At the same time, most individuals are routinely subjected to standard clinical laboratory examinations, which create large health datasets over a lifetime. Computer processing has been used to search for health anomalies and predict diseases using clinical examinations. This work studied machine learning models to support the screening of diabetes through routine laboratory tests using data from laboratory tests of 62,496 patients. The classification and regression models used were the K-nearest neighbor, support vector machines, Bayes naïve, random forest models, and artificial neural networks. Glycated hemoglobin, a test used for diabetes diagnosis, was used as the target. Regression models calculated glycated hemoglobin directly and were later classified. The performance of classification computer models has been studied under various subdataset partitions and combinations (e.g., healthy, prediabetic, and diabetes, as well as no healthy and no diabetes). The best single performance was achieved with the artificial neural network model when detecting prediabetes or diabetes. The artificial neural network classification model scored 78.1%, 78.7%, and 78.4% for sensitivity, precision, and F1 scores, respectively, when identifying no healthy group. Other models also had good results, depending on what is desired. Machine learning-based models can predict glycated hemoglobin values from routine laboratory tests and can be used as a screening tool to refer a patient for further testing.

Estresse no trabalho e níveis de hemoglobina glicada: o papel da escolaridade. Dados da linha de base do Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil)

Resumo Introdução: as condições estressantes do trabalho estão associadas ao aumento dos níveis glicêmicos, mas pouco se conhece sobre o papel da escolaridade neste contexto. Objetivos: analisar a associação entre o estresse psicossocial no trabalho e os níveis de hemoglobina glicada (HbA1c) e a influência da escolaridade como modificador de efeito. Métodos: estudo transversal com dados de 11.922 trabalhadores ativos da linha de base do Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). O estresse psicossocial no trabalho foi avaliado pelo modelo demanda-controle. Foram empregadas a regressão logística multinomial e interações multiplicativas. Resultados: em trabalhadoras do sexo feminino com baixa escolaridade, observou-se associação entre baixo uso de habilidades no trabalho (OR 1,56; IC95% 1,09-2,24) e HbA1c elevada. A baixa autonomia no trabalho foi relacionada à HbA1c limítrofe (OR 1,21; IC95% 1,01-1,45) e elevada (OR 1,73; IC95% 1,19-2,51). Entre trabalhadores do sexo masculino com baixa escolaridade, o trabalho de alto desgaste (OR 1,94; IC95% 1,18-3,21), o baixo uso de habilidades (OR 2,00; IC95% 1,41-2,83) e a baixa autonomia no trabalho (OR 1,58; IC95% 1,13-2,21) foram associados à HbA1c elevada. Conclusão: o estresse psicossocial no trabalho foi associado a níveis limítrofes e elevados de HbAlc para trabalhadores com baixa escolaridade de ambos os sexos. Assim, ações para modificar as relações de trabalho e prevenir doenças crônicas devem ser priorizadas.

New Validated Method for Quantification of Glycated Hemoglobin by LC-QToF-MS: Is HRMS Able to Quantify Clinical Samples?

High-resolution mass spectrometry is a powerful tool in clinical analysis but remains less explored due to its lower dynamic range and sensitivity compared to triple quadrupoles. Glycated hemoglobin (HbA1c) is the current gold standard biomarker to monitor the control of diabetes, representing long-term plasma glycemic levels. Due to its clinical importance, several methods have been developed for HbA1c quantification, using different principles; however, the results obtained with these techniques may differ according to the method adopted. Hence, there is a great need to standardize the current methods to quantify glycated hemoglobin. A new UPLC-QToF-MS method was fully validated and tested to quantify HbA1c in human samples. The peptides VHLTPE m/z 695.373 and gly-VHLTPE m/z 857.426, obtained via Glu-C digestion, were the selected peptides for quantification of HbA1c (mmol/mol). Chromatographic separation was obtained in a C18 column, maintained at 40 °C. The mobile phase was composed of water and acetonitrile, both containing 0.02% TFA and 0.1% acetic acid, and eluted in gradient mode. The method was fully validated, being considered linear in the range of 25-107 mmol/mol of HbA1c, and was sensitive, selective, precise, accurate, and free of matrix and carryover effects. The method was successfully applied to real samples, reaching about 90% agreement with reference method results, providing accurate and precise information on peptide mass, without laborious sample preparation. These results support the use of HRMS to improve the quality of quantitative results of HbA1c in health services and demonstrate a possible application of peptide investigation for clinical analysis in the near future.

Combined Use of Job Stress Models and the Incidence of Glycemic Alterations (Prediabetes and Diabetes): Results from ELSA-Brasil Study

Evidence of psychosocial stress at work as a risk factor for diabetes and prediabetes is restricted.

OBJECTIVES

Analyze the independent and combined association of the models, demand-control and social support (DC-SS) and the effort-reward imbalance and overcommitment (ERI-OC), and the incidence of glycemic alterations (prediabetes and diabetes).

METHODS

A prospective study was carried out with data from 7503 active workers from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) study in the period 2008-2014. Work stress was measured by two stress models. Glycemic levels were evaluated by glycated hemoglobin (HbA1c) in two moments and classified in four groups: normal, maintenance of prediabetes, incident prediabetes, and incident diabetes. Multinomial logistic regression was analyzed with 5% significance levels stratified by sex, and multiplicative interactions were investigated.

RESULTS

Work stress and glycemic alterations were more frequent in women. Psychosocial stress at work was shown to be associated to the risk of prediabetes and diabetes only among women. For women, the combination of models enlarged the magnitude of the association: prediabetes (DC-ERI = OR 1.51, 95% CI 1.15-1.99) and diabetes (DC-ERI = OR 2.10, 95% CI 1.20-3.65). Highly-educated women exposed to ERI-OC were four times more likely to have diabetes.

CONCLUSION

Both models may contribute to explaining the psychosocial stress load according to each pattern of glycemic alteration among women.

HbA1c levels in individuals heterozygous for hemoglobin variants

Summary Objective: To evaluate the levels of glycated hemoglobin (HbA1c) in patients heterozygous for hemoglobin variants and compare the results of this test with those of a control group. Method: This was an experimental study based on the comparison of HbA1c tests in two different populations, with a test group represented by individuals heterozygous for hemoglobin variants (AS and AC) and a control group consisting of people with electrophoretic profile AA. The two populations were required to meet the following inclusion criteria: Normal levels of fasting glucose, hemoglobin, urea and triglycerides, bilirubin > 20 mg/dL and non-use of acetylsalicylic acid. 50 heterozygous subjects and 50 controls were evaluated between August 2013 and May 2014. The comparison of HbA1c levels between heterozygous individuals and control subjects was performed based on standard deviation, mean and G-Test. Results: The study assessed a test group and a control group, both with 39 adults and 11 children. The mean among heterozygous adults for HbA1c was 5.0%, while the control group showed a rate of 5.74%. Heterozygous children presented mean HbA1c at 5.11%, while the controls were at 5.78%. G-Test yielded p=0.93 for children and p=0.89 for adults. Conclusion: Our study evaluated HbA1c using ion exchange chromatography resins, and the patients heterozygous for hemoglobin variants showed no significant difference from the control group.

[The influence of quality of life in treatment adherence of diabetic patients: a systematic review]

OBJECTIVE

To verify the influence of quality of life in treatment adherence of patients with diabetes mellitus.

METHOD

Systematic review of the literature using the databases MEDLINE, CINAHL, Scopus, LILACS, SciELO and Web of Science with studies published between 2003 and 2014 in English, Portuguese or Spanish.

RESULTS

Six studies were included in the review, three were identified as having better quality of life scores, being related to better adherence to diabetes treatment measured by glycated hemoglobin or characteristics related to diet, exercise, use of medication and foot care. No association was found between quality of life and adherence in two investigations and a study found a negative association between these variables.

CONCLUSION

There is causal relationship between quality of life and adherence with diabetes treatment. It is suggested that psychosocial aspects of patients should be considered by health professionals in the search for better clinical outcomes in diabetes care.

Efficacy of pre-exercise low-level laser therapy on isokinetic muscle performance in individuals with type 2 diabetes mellitus: study protocol for a randomized controlled trial

Background

Type 2 diabetes, also known non-insulin-dependent diabetes, is the most prevalent type of the disease and involves defects in the secretion and action of insulin. The aim of the proposed study is to evaluate the efficacy of pre-exercise low-level laser therapy (LLLT) on muscle performance of the quadriceps femoris in individuals with type 2 diabetes.

Methods/Design

A double-blind, randomized, controlled clinical trial will be carried out in two treatment phases. In the first phase, quadriceps muscle performance will be evaluated using an isokinetic dynamometer and the levels of creatine kinase and lactate dehydrogenase (biochemical markers of muscle damage) will be determined. The participants will then be allocated to four LLLT groups through a randomization process using opaque envelopes: Group A (4 Joules), Group B (6 Joules), Group C (8 Joules) and Group D (0 Joules; placebo). Following the administration of LLLT, the participants will be submitted to an isokinetic eccentric muscle fatigue protocol involving the quadriceps muscle bilaterally. Muscle performance and biochemical markers of muscle damage will be evaluated again immediately after as well as 24 and 48 hours after the experimental protocol. One week after the last evaluation the second phase will begin, during which Groups A, B and C will receive the LLLT protocol that achieved the best muscle performance in phase 1 for a period of 4 weeks. At the end of this period, muscle performance will be evaluated again. The protocol for this study is registered with the World Health Organization under Universal Trial Number U1111-1146-7109.

Discussion

The purpose of this randomized clinical trial is to evaluate the efficacy of pre-exercise LLLT on the performance of the quadriceps muscle (peak torque, total muscle work, maximum power and fatigue index – normalized by body mass) in individuals with DM-2. The study will support the practice of evidence-based to the use of LLLT in improving muscle performance in Individuals with DM-2. Data will be published after the study is completed.

Beta thalassemia and energy consumption in hemoglobin A1C formation: a model

Hemoglobin (Hb) A1C is the nonenzymatic glycated product of the Hb beta chain at the valine terminal residue. Recently, the nature of energy-consuming reaction in HbA1C formation was reported, and this was proposed as an underlying pathophysiology for poor nutritional status, muscle loss, and functional impairment in poor-control diabetic patients. Here, the author focuses on energy change in HbA1C formation in the case of beta thalassemia. According to this study, the energy range required for any type of beta thalassemia is greater than that required for normal Hb. Hence, it might be expressed that beta thalassemia did significantly increase complications due to energy consumption during HbA1C formation in poor-control diabetic cases.

Problem of using hemoglobin A1C measurement in endemic area of hemoglobinopathy

Diabetes mellitus (DM) is a frequent disorder affecting individuals of all ages. Glycohemoglobin (GHb) has a key role in the assessment of glycemic control in diabetic patients. Generally, GHb is measured as hemoglobin (Hb) A1C and is the result of an irreversible non-enzymatic glycation of the beta chain of hemoglobin A. HbA1C is used routinely to assess long term glycemic control in patients with DM. A variety of patient- and laboratory-related factors can adversely affect the measurement of HbA1C in patients harboring Hb variants or derivatives. In this article, problem of using hemoglobin A1C measurement in endemic area of hemoglobinopathy is addressed.