False measurement of glycated hemoglobin in patients without hemoglobin A

Glycation resistance and life-history traits: lessons from non-conventional animal models

Glycation reactions play a key role in the senescence process and are involved in numerous age-related pathologies, such as diabetes complications or Alzheimer's disease. As a result, past studies on glycation have mostly focused on human and laboratory animal models for medical purposes. Very little is known about glycation and its link to senescence in wild animal species. Yet, despite feeding on high-sugar diets, several bat and bird species are long-lived and seem to escape the toxic effects of high glycaemia. The study of these models could open new avenues both for understanding the mechanisms that coevolved with glycation resistance and for treating the damaging effects of glycations in humans. Our understanding of glycaemia's correlation to proxies of animals' pace of life is emerging in few wild species; however, virtually nothing is known about their resistance to glycation, nor on the relationship between glycation, species' life-history traits and individual fitness. Our review summarizes the scarce current knowledge on the links between glycation and life-history traits in non-conventional animal models, highlighting the predominance of avian research. We also investigate some key molecular and physiological parameters involved in glycation regulation, which hold promise for future research on fitness and senescence of individuals.

Significantly High HbA1c in Diabetic Patient with Hb J: Case Report

Glycated hemoglobin (HbA_1c) is used to monitor the long-term management of diabetes and reflects the average blood glucose level over the past three months. Hb J is an alpha-globin gene variant that occurs less commonly but can interfere with the HbA_1c result. This case report presents two cases of abnormally high HbA_1c in patients with Hb J using the high-performance liquid chromatography (HPLC) method and repeated value using the capillary electrophoresis (CE) method. The first case was a 26 years old female Malay patient, presenting at 25 weeks gestation with diabetes mellitus (DM). Her HbA_1c results from HPLC showed persistently high level (> 18.5%, > 179 mmol/mol) despite optimum diabetic control (fasting blood sugar (FBS) range 4.0–6.1 mmol/L). The second case was a 62-year-old female Malay with type 2 DM. Her HbA_1c results from HPLC was also persistently high (> 18.5%, > 1;79 mmol/mol) despite good diabetic control (FBS average 5.0–7.0 mmol/L). Both patients’ hemoglobin analysis reports were suggestive of Hb J. Repeated HbA_1c using CE were 6.0% (42 mmol/mol) and 8.1% (65 mmol/mol), respectively, and supported the presence of the Hb J variant peak. HbA_1c measurement in patients with a variant should be interpreted with caution to avoid misdiagnosis and mismanagement in these kinds of patients.

Resistance to glycation in the zebra finch: Mass spectrometry-based analysis and its perspectives for evolutionary studies of aging

In humans, hyperglycemia is associated with protein glycation, which may contribute to aging. Strikingly, birds usually outlive mammals of the same body mass, while exhibiting high plasma glucose levels. However, how birds succeed in escaping pro-aging effects of glycation remains unknown. Using a specific mass spectrometry-based approach in captive zebra finches of known age, we recorded high glycaemia values but no glycated hemoglobin form was found. Still, we showed that zebra finch hemoglobin can be glycated in vitro, albeit only to a limited extent compared to its human homologue. This may be due to peculiar structural features, as supported by the unusual presence of three different tetramer populations with balanced proportions and a still bound cofactor that could be inositol pentaphosphate. High levels of the glycated forms of zebra finch plasma serotransferrin, carbonic anhydrase 2, and albumin were measured. Glucose, age or body mass correlations with either plasma glycated proteins or hemoglobin isoforms suggest that those variables may be future molecular tools of choice to monitor glycation and its link with individual fitness. Our molecular advance may help determine how evolution succeeded in associating flying ability, high blood glucose and long lifespan in birds.

The Interaction between Hb A1C and Selected Genetic Factors in the African American Population in the USA

BACKGROUND

The global prevalence of diabetes mellitus has been growing in recent decades and the complications of longstanding type 2 diabetes continue to place a burden on healthcare systems. The hemoglobin A1c (Hb A1c) content of the blood is used to assess an individual's degree of glycemic control averaged over 2 to 3 months. In the USA, diabetes is the seventh leading cause of death. Black, indigenous, people of color (BIPOC) are disproportionately affected by diabetes compared to non-Hispanic whites. There are many reports of interaction of Hb A1c and hematologic conditions that have a high prevalence in the Black population; some of these effects are contradictory and not easily explained. This review attempts to document and categorize these apparently disparate effects and to assess any clinical impact.

METHODS

Hb A1C can be determined by a variety of techniques including cation-exchange chromatography, electrophoresis, immunoassays, and affinity chromatography. The amount of Hb A1c present in a patient specimen depends not only on blood glucose but is strongly influenced by erythrocyte survival and by structural variations in the globin chains. Sickling hemoglobinopathies are well-represented in the USA in African Americans and the effects of these hemoglobin disorders as well as G6PD deficiency is examined.

CONCLUSION

Hb A1c measurement should always be performed with a cautious approach. The laboratory scientist should be aware of possible pitfalls in unquestioningly determining Hb A1c without a consideration of hematologic factors, both inherited and acquired. This presents a challenge as often times, the laboratory is not aware of the patient's race.