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At least 19 recordsLinked to original sources

PubMed2006

Hereditary spherocytosis and other hemolytic anomalies distort diabetic control by glycated hemoglobin.

Glycated hemoglobin (%HbA1c) has become a well established and reliable long term parameter indicative of the mean glucose load of the preceding 8 -10 weeks. A normal life span of approximately120 days of the red blood cells (RBC) is an essential condition. Hemolytic affections are characterized by a shorter life span, reducing the overall glucose uptake and %HbA1c. Measured %HbA1c is no longer correlated with mean blood glucose of the preceding period, simulating false low values. Underestimation of this kind is demonstrated for several hemolytic conditions, among them hereditary spherocytosis (HS). This latter, often harmless anomaly may lead to serious underestimation of glucose load. Recent investigations show not only a much higher incidence of HS than hitherto admitted (approximately 1 in 250 persons) but also an abnormally high incidence of diabetes in this hemolytic affection. In the presence of hemolysis %HbA1c is to be interpreted with caution. This justifies systematic detection of HS in routine hematology using--if available--the increase of the percentage of hyperchromic RBC.

Anemia, Hemolytic↗

PubMed2005

A case of type 2 diabetes mellitus developing hypothyroidism discovered as a result of a discrepancy between glycated hemoglobin and glycated albumin values.

We report a case of type 2 diabetes mellitus presenting hypothyroidism due to overeating of seaweed that was noticed as a result of a discrepancy between glycated albumin (GA) and glycated hemoglobin (GHb). A 71-year-old woman was undergoing managed treatment with oral medicines and insulin for diabetes mellitus with no sign of thyroid disease. Her thyroid function was euthyroid without aid of thyroid hormone. All of the patient's thyroid autoantibodies were negative. Fifteen weeks prior to indications of hypothyroidism, she had started to consume large amounts (100-200 g dry weight equivalent) of cooked "wakame" seaweed every morning. Just before admission to our hospital, her GA was 26.9%, while GHb and fasting plasma glucose remained within normal ranges (less than 5.6%, and 106 mg, respectively). This discrepancy between GA and GHb drew our attention to the development of complications. Naive interview of the patient led us to believe a thyroid hormone deficiency existed, though without any related complaints or findings, such as non-pitting edema, cold intolerance, or easy fatiguing. Seaweed consumption was stopped and periodic observation of thyroid function started. As thyroid hormone levels moved into normal range, GA and GHb returned to their normal relative ratio after 3 months. Thus, measurement of the relative ratio of GA and GHb may be useful for glycemic monitoring, with the potential as a readily available glycemic control marker for patients with changeable complications.

Aged↗

PubMedDate not supplied

High and low hemoglobin glycation phenotypes in type 1 diabetes: a challenge for interpretation of glycemic control.

This study tested the hypothesis that there are consistent individual differences in the relationship between glycated hemoglobin (HbA1c) and mean blood glucose (MBG) levels in individuals with similar preceding blood glucose levels. Blood glucose data were collected for up to 2.3 years by 128 children and adolescents with type 1 diabetes. HbA1c values were date-matched with MBG levels calculated from an average of 85 self-monitored blood glucose measurements collected in the previous 30 days. There was significant linear correlation between MBG and HbA1c (HbA1c=0.027xMBG+5.8, n=682, r=.71, P<.0001) but also wide variability in the population HbA1c response to MBG. We calculated a hemoglobin glycation index (HGI=observed HbA1c-predicted HbA1c) to quantify the magnitude and direction of the difference between each patient's set of observed and predicted HbA1c results. Likelihood ratio tests and t statistics showed that mean HGI were significantly different among individuals, and that 29% of the patients had HbA1c levels that were statistically significantly higher or lower than predicted by the regression equation. The observed individual differences in the relationship between MBG and HbA1c were not related to erythrocyte age and there was no evidence of analytical artifact. We interpret these results as possible evidence of high and low hemoglobin glycation phenotypes within the population. We conclude that MBG and HbA1c are not necessarily interchangeable estimates of glycemic control and that hemoglobin glycation phenotype may be important for the clinical assessment of diabetic patients.

Adolescent↗

PubMed1998

Hyperglycemia in hummingbirds and its consequences for hemoglobin glycation.

We measured levels of glucose and glycated hemoglobin in the blood of three of the world's smallest nectarivorous birds, the Anna's (Calypte anna), Costa's (Calypte costae), and ruby-throated hummingbirds (Archilochus colubris). Plasma glucose levels of hummingbirds that were fasted overnight (17 mM) were higher than those in any mammal and are among the highest ever measured in a fasting vertebrate. Glucose levels in hummingbirds just after feeding were extreme, rising as high as 42 mM. The surprisingly high blood glucose concentrations in hummingbirds were accompanied by glycated hemoglobin levels that are the highest ever measured in birds but are lower than those of non-diabetic humans. How hummingbirds tolerate blood glucose levels that cause serious neurological and microvascular pathologies in diabetic humans and animals remains unknown.

Animals↗

PubMed1991

A comparison of home glucose monitoring with determinations of hemoglobin A1c, total glycated hemoglobin, fructosamine, and random serum glucose in diabetic patients.

We compared four objective measures of glycemic control (fructosamine, total glycated hemoglobin, hemoglobin A1c, and random serum glucose) with home glucose monitoring records in 17 diabetic patients followed up prospectively for 4 months. There was good overall correlation between all of these objective measures and weekly mean capillary glucose values. However, considerable scatter was seen in the data such that none of the glycated protein measurements was an ideal predictor of home glucose values. For example, all markedly elevated home glucose levels (greater than 11.1 mmol/L) were associated with elevated glycated protein levels, but moderately high blood glucose levels (8.3 to 11.1 mmol/L) were associated with one or more normal glycated protein values in some patients. Similar correlations were obtained whether glycemia was estimated by 1-week or 6-week home averages. Random serum glucose level also correlated with average home glucose level; however, there was wide fluctuation within individual subjects. All three glycated protein measurements (hemoglobin A1c, glycated hemoglobin, and fructosamine) appear equally useful as a supplement to home glucose monitoring in the assessment of glycemic control. Of the three types of glycated protein assays, fructosamine, with its advantage of speed and simplicity, may offer a more cost-effective alternative.

Adolescent↗

PubMed1992

Glycated hemoglobin of fractionated erythrocytes, glycated albumin, and plasma fructosamine during pregnancy.

OBJECTIVE: To evaluate glucose metabolism during pregnancy, we measured plasma fructosamine, glycated albumin, and the stable glycated hemoglobin of the light and dense erythrocytes. STUDY DESIGN: The abnormal glucose tolerance group comprised patients with gestational diabetes and those with one abnormal value on a 75 gm oral glucose tolerance test. Erythrocyte fractionation was performed by capillary centrifugation. RESULTS: In normal pregnancy glycated hemoglobin of the light erythrocytes was reduced in the second and third trimesters (3.42% +/- 0.62% [mean +/- SD] [n = 306] in the first trimester, 2.15% +/- 0.48% [n = 353] in the second, and 2.06% +/- 0.58% [n = 300] in the third), and dense erythrocytes were higher in the third trimester (first 4.59% +/- 0.46%, second 4.70% +/- 0.49%, third 5.29% +/- 0.73%). Glycated albumin and fructosamine followed a pattern similar to the light erythrocytes. The group with abnormal glucose tolerance had significantly higher levels of glycated hemoglobin of the light erythrocytes in the first and third trimesters and glycated hemoglobin of the dense erythrocytes and glycated albumin in all trimesters. CONCLUSION: The biphasic change in nonfractionated glycated hemoglobin is the sum of the lower glycated hemoglobin of the light erythrocytes and the higher glycated hemoglobin of the dense erythrocytes in late pregnancy. The stable glycated hemoglobin of fractionated erythrocytes and the glycated albumin accurately reflect maternal glucose metabolism during pregnancy.

Adult↗

PubMed1985

Cord blood glycosylated (glycated) hemoglobin: correlation with maternal glycosylated (glycated) hemoglobin and birth weight.

Maternal and cord blood glycosylated hemoglobin levels were measured by an affinity chromatographic method in three groups: normal women (nondiabetic women who gave birth to infants that were normal for gestational age); test women (women who had no evidence of glucose intolerance with screening procedures and who gave birth to large-for-gestational age infants); and women with gestational diabetes. In all cases the level of cord blood glycosylated hemoglobin was approximately 40% less than the corresponding maternal blood levels, and no correlation could be detected between maternal and cord blood concentrations. The reference range for glycosylated hemoglobin in the normal maternal population was similar to that for nonpregnant adults. There was no significant difference in cord and maternal glycosylated hemoglobin levels among the three groups, although a slight upward trend was detected in the diabetic group. There was a lack of correlation of cord and maternal glycosylated hemoglobin with birth weight in all three groups. The implications of these findings are discussed in respect to the usefulness of cord and maternal glycosylated hemoglobin in retrospective screening for gestational diabetes.

Adult↗

PubMed1994

Ion-exchange microchromatography and thiobarbituric acid colorimetry for the measurement of canine glycated hemoglobins.

Nonenzymatic glycation of hemoglobin is a slow, continuous, and irreversible process which takes place during the whole lifespan of the erythrocyte. When hemolytic diseases are ruled out, the levels of glycated hemoglobins reflect the time-averaged serum glucose concentration for the preceding weeks. Canine hemoglobin also binds physiologically to intraerythrocytic glucose to form a glycated fraction which provides information on the animal's long-term glycemic status. This study describes an overall evaluation of ion-exchange microchromatography and thiobarbituric acid (TBA) colorimetry for the measurement of canine glycated hemoglobins. The intra- and inter-assay coefficients of variation (CVs) found were less than 5% in normal and diabetic canine samples, and both assays proved linear over the analytical range tested, which was wide enough to include the expected clinical values. Under our laboratory's conditions, the reference range for HbA(1) was 5.82 +/- 0.62% and for HbA(1)c was 2.35 -/+ 0.47%. Sample stability was lower using the ion-exchange procedure, with increases in HbA(1) observed after 4 days in whole blood and hemolysates stored at room temperature, after 12 days in whole blood stored at 4 degrees C, and after 7 days in hemolysates stored at 4 degrees C and -20 degrees C. In the case of TBA colorimetry, whole blood was stable for at least 21 days at room temperature and at 4 degrees C, and hemolysates were stable for 18 days at room temperature, at least 21 days at 4 degrees C, and up to 3 months at -20 degrees C.

Journal Article↗

PubMed1997

A case of X-linked alpha-thalassemia/mental retardation syndrome: analysis of hemoglobin by an automated glycated hemoglobin analyzer.

A 5-year-old male patient with X-linked alpha-thalassemia/mental retardation syndrome is reported. He showed multiple minor anomalies including characteristic facial abnormalities, alpha-thalassemia, severe mental retardation, and hypogonadism. Analysis of his hemoglobin by high performance liquid chromatography using an automated glycated hemoglobin analyzer revealed an abnormal peak. Identification of an abnormal peak by an automated glycated hemoglobin analyzer will aid in the diagnosis of patients with X-linked alpha-thalassemia/mental retardation syndrome.

Abnormalities, Multiple↗

PubMed1991

Production and characterization of monoclonal antibodies against non-A1c glycated hemoglobin.

Hybridomas secreting monoclonal antibodies specific for hemoglobin nonenzymatically glycated in the non-A1c position were produced by fusion of SP 2/0 myeloma cells with spleen cells from BALB/c mice immunized with nonenzymatically glycated hemoglobin prepared from human erythrocytes. Wells containing hydridomas secreting antibodies against glycohemoglobin were identified by binding, in an enzyme-linked immunosorbent assay, to purified glycated hemoglobin. The colony designated E85, which secreted antibodies discriminating between glycated versus unglycated hemoglobin, was cloned at least four times by limiting dilution and used for further study, performed with purified monoclonal antibody. Specificity of E85 was demonstrated by immunoblotting and by ELISA, wherein the monoclonal antibody reacted with glycated hemoglobin but not with hemoglobin A1c or with unglycated hemoglobin. Immunoblotting of human plasma with E85 on nitrocellulose yielded no reactive proteins, indicating site specificity for glycated epitopes residing in hemoglobin but not in other nonenzymatically glycated proteins present in plasma. E85 differs from other antibodies raised against glycated hemoglobin and other glycated proteins, which recognize hemoglobin glycated at the N terminal valine of the beta chain (HbA1c) or which recognize glycated residues only after reductive conversion to glucitollysine and which do not discriminate between different glycated proteins. Thus, this report describes the establishment of the first hybridoma secreting monoclonal antibody raised against a physiologic (unreduced) form of non-A1c glycohemoglobin, and for the glycated epitope when it resides in glycohemoglobin but not in other proteins or in hemoglobin A1c.

Antibodies, Monoclonal↗

PubMed1991

Purification of glycated hemoglobin free of hemoglobin A1c and its use to produce monoclonal antibodies specific for deoxyfructosyllysine [correction of deoxyfructosyllsine] residues in glycohemoglobin.

Hemoglobin nonenzymatically glycated at E-amino groups of lysine residues was purified from human erythrocyte lysates and used for immunization of BALB/c mice. Hybridomas secreting monoclonal antibodies for glycated hemoglobin were produced by fusion of mouse spleen cells with SP 2/0 myeloma cells. Immunoblotting with purified monoclonal antibody demonstrated specificity for glycated hemoglobin, with no reaction with HbAO. Glycated hemoglobin was effectively separated from other hemoglobins upon application of erythrocyte lysates to an affinity column of monoclonal antibody immobilized onto Sepharose 4B. A small fraction of purified HbA1c adsorbed to the monoclonal antibody affinity column, indicating that glycation can occur at both E-amino lysine and N-terminal valine positions in the same molecule. HbA1c did not react with the antibody after removal by immunoadsorption of molecules containing glycated lysine, confirming specificity of the antibody for deoxyfructosyl-lysine residues. The findings indicate that these monoclonal antibodies are site specific for glycated lysine amino groups in hemoglobin, and can provide rapid and efficient separation and identification of glycated hemoglobin in human erythrocyte lysates.

Animals↗

PubMedDate not supplied

Hemoglobin variants and determination of glycated hemoglobin (HbA1c).

Measurement of glycated hemoglobin in diabetic patients is an established procedure for evaluating long-term control of diabetes. The Diabetes Control and Complications Trial (DCCT), as well as the United Kingdom Prospective Diabetes Study (UKPDS), confirmed the direct relationship between the degree of glycemic control as estimated by glycohemoglobin (GHb) determinations and the development and progression of long-term complications in diabetic patients. Samples with known interferences of HbA(1c) determination as hemoglobinopathies are specifically excluded from certification testing and there are no guidelines or requirements for comparability of samples containing hemoglobin (Hb) variants. This paper reviews the interference of Hb variants on determination methods of glycated hemoglobin as they result in false HbA(1c) results.

Biomarkers↗

PubMed1988

Hemoglobin hafnia: alpha 2 (beta 116 (G18) His----Gln)2; a new hemoglobin variant mistaken for glycated hemoglobin.

Isoelectric focusing of hemolysate from patients with diabetes mellitus is routinely performed to measure their level of HbA1c (glycated hemoglobin). For a 6 year old boy with diabetes mellitus this analysis showed an HbA1c fraction of approx. 50%, which is very unlikely to occur. The possibility of a hemoglobin variant was considered, and by HPLC-separation the presence of two different beta-chains was shown. One tryptic fragment was found to deviate from the normal, and amino-acid analysis and sequence determination revealed the following amino-acid substitution: beta 116 His----Gln. It is the first reported mutation at this position. Functional studies showed almost normal behaviour, consistent with the fact that the affected persons are without any symptoms. In a family survey we found five nondiabetic members with an abnormality similar to the proband. For the variant we chose the name Hafnia, which is Latin for Copenhagen.

Amino Acid Sequence↗

PubMed1988

Postmortem diagnosis of diabetes mellitus. Quantitation of fructosamine and glycated hemoglobin.

Fructosamine and glycated hemoglobin were determined in samples from 52 cadavers autopsied in the Forensic Pathology Institute of the University of Copenhagen (Denmark). The population studied comprised 15 adult subjects with history of diabetes mellitus and 37 adult non-diabetic subjects. The fructosamine/total protein ratio was 1.7 times higher in diabetic than in non-diabetic subjects, as was the case for glycated hemoglobin. Measurement of glycated serum protein appears to be a useful tool for the postmortem diagnosis of fatal diabetic coma and glucose concentration before death.

Adult↗

PubMed1999

The narrow therapeutic window of glycated hemoglobin and assay variability.

Glycated hemoglobin is measured by a variety of assays, each of which has a unique normal level. Our purpose is to show that among the different assays available in the United States, using the same patient's blood sample, assay results may vary widely and may more or less easily achieve a glycated hemoglobin value within the normal range. The following assays were compared using the same patient's blood sample for each pair of assays: glycohemoglobin affinity assay (GHB Reader; Isolab, Akron, OH) versus gel electrophoresis assay (n = 76); Isolab versus ion capture assay (IMX; Abbott Laboratories, Irving, TX) (n = 57); monoclonal antibody assay (DCA2000; Bayer Diagnostics, Pittsburgh, PA) versus IMX (n = 100); and high-performance liquid chromatography (HPLC) assay (Bio-Rad Variant A1c; Bio-Rad Laboratories, Richmond, CA) versus IMX assay (n = 55). Our analyses indicate that a relative ranking can be established for the ease of achieving a normal glycated hemoglobin level. The ranking indicates that the most stringent or difficult assays for achieving a normal level are the Isolab and DCA2000 assays. The intermediate assays are the IMX and Bio-Rad Variant, and the easiest method for achieving a normal value is the gel electrophoresis assay. Our results indicate that various glycated hemoglobin assays vary widely and are associated with more or less difficulty for an individual patient to achieve a glycated hemoglobin level within the normal range. These results are especially significant with respect to (1) the clinically narrow therapeutic window of glycated hemoglobin values in type 1 diabetes to avoid rapidly advancing severe hypoglycemia rates and chronic microvascular complication rates, and (2) the glycated hemoglobin threshold for rapidly advancing macrovascular disease in both type 1 and type 2 patients.

Adolescent↗

PubMed2002

[Determination of glycated hemoglobins (Hb A1c)].

Glycated hemoglobin is measured as HbA1c 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 diabetes mellitus. There are more than 20 determination methods, the techniques used are cation-exchange chromatography, electrophoresis, affinity chromatography and immunoassays, although each of these techniques measures a different fraction of the glycated hemoglobin. In addition, genetic hemoglobin variants and chemically modified derivates of hemoglobin can affect the HbA1c measurement and thus can not be included in international attempts for standardization. This manuscript reviews the current information on glycation of hemoglobin, HbA1c determination methods, interferences and attempts for standardization. We aim at pointing out to the reader the current problems of glycated hemoglobin determination and to describe the necessary measures which need to be taken for proper measurement of HbA1c.

Diabetes Mellitus↗

PubMed1986

Sensitivity of isoelectric focusing, ion exchange, and affinity chromatography to labile glycated hemoglobin.

We examined the effect of labile glycated hemoglobin on measurements of glycated hemoglobin by several commercial procedures. Erythrocytes from diabetic and nondiabetic patients were incubated in vitro with various concentrations of glucose, to generate labile glycated hemoglobin, and the species of glycated and nonglycated hemoglobin in each sample were identified by isoelectric focusing. Glycated hemoglobin was then assayed by the Bio-Rad A1 column method (I), the Bio-Rad A1c column method (II), and the Pierce affinity column method (III). I was sensitive to the labile (aldimine) fraction of glycated hemoglobin, and percentages of glycated hemoglobin so determined represented the sum of the labile fraction plus hemoglobin A1c and other stable glycated species. This spurious increase in glycated hemoglobin concentration by the aldimine could be obviated by any of three wash procedures, which eliminated the labile fraction from the samples: incubating the erythrocytes (a) in phosphate-buffered saline (pH 7.4) for 18 h at 22 degrees C, (b) in 100 mmol/L citrate (pH 5.0) for 30 min at 37 degrees C, or (c) in saline containing, per liter, 30 mmol of semicarbazide and 12 mmol of aniline hydrochloride (pH 5.0) for 30 min at 37 degrees C. Methods II and III did not detect the labile fraction. However, treatments a-c decreased the concentrations of stable glycated hemoglobin as determined by all three column-chromatographic methods as compared with unwashed sample. By isoelectric focusing we determined that blood with high glucose content had concentrations of aldimine roughly proportional to the blood glucose concentration. The kinetics of formation of labile glycated hemoglobin in these cells were consistent with the reported rate constants determined by using purified hemoglobin preparations in vitro.

Chromatography, Affinity↗

PubMed2004

Fructosamine, glycated hemoglobin, and dietary carbohydrates.

BACKGROUND: Glycated hemoglobin (HbA(1c)), a marker of glycemia in the previous 3 months, was found to be associated with dietary saturated, fat but not with carbohydrates, in recent population surveys. Another nonenzymatically glycated substance in the blood, fructosamine, a marker of glycemia in the previous 3 weeks, is poorly correlated with HbA(1c) in nondiabetic subjects. The aim of this study is to compare the correlation of glycated hemoglobin and fructosamine with dietary carbohydrate intake in the same subjects. SUBJECTS AND METHODS: Seventy-one individuals from a cohort study on diet and cancer entered this study. Serum fructosamine was measured by a standard colorimetric method, and glycated hemoglobin by high-performance liquid chromatography (HPLC). Diet was measured by a validated semiquantitative food frequency questionnaire. The correlation of fructosamine and glycated hemoglobin with dietary variables, corrected for calories, was evaluated by multiple correlation. RESULTS: Fructosamine was more strongly correlated with dietary sugar (r=0.26, p=0.05) than HbA(1c) was (r=0.001, p=0.99). Fructosamine was also inversely correlated with energy, and glycated hemoglobin with vitamin C. CONCLUSIONS: Fructosamine appears to be more related to dietary sugar intake than glycated hemoglobin and may be a marker of exposure to dietary carbohydrates, particularly simple sugars, in epidemiological studies.

Aged↗