Possible link between glycated hemoglobin and lipid peroxidation in hyperthyroidism

Efficacy of a Methanolic Extract of Adansonia digitata Leaf in Alleviating Hyperglycemia, Hyperlipidemia, and Oxidative Stress of Diabetic Rats

Traditionally, in many countries, various parts of the Adansonia digitata (A. digitata) tree have been used in the treatment of many clinical ailments including diarrhea and dysentery. The phytochemical screening has indicated that the leaf extract of A. digitata contains flavonoids, saponins, mucilage, steroids, and alkaloids. Thus, this paper aims to evaluate the hyperglycaemic and hypolipidaemic effects of methanolic extract of A. digitata leaves (200 mg/kg and 400 mg/kg) in diabetic rats. The extract was administered orally for six weeks in the streptozotocin (STZ)-induced diabetic rats. The treatment with the extract caused a significant reduction in the blood glucose, glycosylated hemoglobin, cholesterol, triglycerides, low-density lipoprotein (LDL), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and malondialdehyde (MDA) levels by 46.7%, 46.15%, 48.91%, 43%, 60%, 66%, 45.45%, and 30.4%, respectively, as compared to the diabetic group after the sixth week of treatment. The leaf extract also mitigated the decline of high-density lipoprotein (HDL) level, RBCs count, hemoglobin level, packed cell volume (PCV %), and erythropoietin concentration in diabetic rats by 31%, 33.25%, 24.72%, 51.42%, and 220.68% with respect to the diabetic group. Also, the extract maintained the level of antioxidant enzymes, catalase (CAT) and superoxide dismutase (SOD), and reduced glutathione (GSH) in the diabetic rats. It also reduced the elevation in the white blood corpuscles (WBC) count in the STZ-induced diabetic rats. Our study, therefore, indicates that methanolic extract of A. digitata leaf exerts strong antidiabetic and hypolipidaemic properties in a dose-dependent manner by improving the hematological properties and redox parameters in the experimental diabetic rats.

Comparing glucose and hemoglobin A1c diagnostic tests among a high metabolic risk Hispanic population

BACKGROUND

Compare glycated hemoglobin (HbA1c ) diagnostic tests for prediabetes and diabetes with plasma glucose criteria and compare the metabolic profiles of people classified by HbA1c versus by glucose levels.

METHODS

Participants were recruited for the San Juan Overweight Adults Longitudinal Study. The participants were primarily Hispanic (98%), without previously diagnosed diabetes, and aged 40 to 65 years. Participants classified as normal glycemic, prediabetes, or diabetes on the basis of baseline HbA1c and plasma glucose criteria were compared with respect to baseline cardiometabolic factors.

RESULTS

The 1342 participants had a mean age of 50.5 ± 6.8 years and 28% were men. Thirty-one percent were diagnosed with prediabetes by plasma glucose criteria and 53.4% by HbA1c , and 8.1% were diagnosed with diabetes by plasma glucose criteria and 6.3% by HbA1c ; overall concordance rate was 55.1%. The area under the receiver operating characteristic curve of HbA1c compared to plasma glucose criteria was 0.62 for impaired glucose and 0.76 for diabetes. A worse cardiometabolic profile was seen within subgroups that met HbA1c and plasma glucose criteria for diabetes or prediabetes. Those diagnosed with prediabetes by plasma glucose criteria had significantly higher systolic blood pressure and higher homeostatic model assessment than those diagnosed using HbA1c . Participants diagnosed with diabetes by plasma glucose criteria had lower body mass index, smaller waist circumference, and lower insulinogenic and disposition indices, but higher homeostatic model assessment of insulin resistance, than those diagnosed by HbA1c .

CONCLUSIONS

Low concordance was seen between HbA1c and glucose measurements. The HbA1c is not a good test for prediabetes but shows reasonable validity for diabetes in this high-risk predominantly female Hispanic population. People classified by HbA1c , plasma glucose criteria, or both show different metabolic profiles; a combined test may be ideal.

Effects of thyroid status on glycated hemoglobin

INTRODUCTION

Glycated hemoglobin (HbA1c) can be altered in different conditions. We hypothesize that HbA1c levels may change due to altered thyroid status, possibly due to changes in red blood cell (RBC) turnover.

OBJECTIVES

The objective of this study was to determine the effects of altered thyroid status on HbA1c levels in individuals without diabetes, with overt hyper- and hypo-thyroidism, and if present, whether such changes in HbA1c are reversed after achieving euthyroid state.

METHODS

Euglycemic individuals with overt hypo- or hyper-thyroidism were selected. Age- and sex-matched controls were recruited. Baseline HbA1c and reticulocyte counts (for estimation of RBC turnover) were estimated in all the patients and compared. Thereafter, stable euthyroidism was achieved in a randomly selected subgroup and HbA1c and reticulocyte count was reassessed. HbA1c values and reticulocyte counts were compared with baseline in both the groups.

RESULTS

Hb A1c in patients initially selected was found to be significantly higher in hypothyroid group. HbA1c values in hyperthyroid patients were not significantly different from controls. HbA1c reduction and rise in reticulocyte count were significant in hypothyroid group following treatment without significant change in glucose level. Hb A1c did not change significantly following treatment in hyperthyroid group. The reticulocyte count, however, decreased significantly.

CONCLUSION

Baseline HbA1c levels were found to be significantly higher in hypothyroid patients, which reduced significantly after achievement of euthyroidism without any change in glucose levels. Significant baseline or posttreatment change was not observed in hyperthyroid patients. Our study suggests that we should be cautious while interpreting HbA1c data in patients with hypothyroidism.

Increased hemoglobin A1c threshold for prediabetes remarkably improving the agreement between A1c and oral glucose tolerance test criteria in obese population

CONTEXT

It is unclear why the prevalence of diabetes and prediabetes, especially prediabetes, between diagnosed by oral glucose tolerance test (OGTT) and hemoglobin A1c (HbA1c) criteria, is substantially discordant.

OBJECTIVE

We aimed to evaluate the effects of obesity on the agreement between HbA1c and OGTT for diagnosing diabetes and prediabetes and identify the optimal HbA1c cutoff values in different body mass index (BMI) classifications.

DESIGN SETTING AND PARTICIPANTS

In a population-based, cross-sectional study in Harbin, China, 4325 individuals aged 20-74 years without a prior diagnosed diabetes were involved in this study.

OUTCOME

measure The performance and optimal cutoff points of HbA1c were assessed by receiver-operating characteristic curve. The contribution of BMI to HbA1c was analyzed by structural equational model.

RESULTS

The agreement between HbA1c criteria and OGTT decreased with BMI gain (κ = 0.359, 0.312, and 0.275 in a normal weight, overweight, and obese population, respectively). The structural equational model results showed that BMI was significantly associated with HbA1c in normal glucose tolerance and prediabetes subjects but not in diabetes subjects. At a specificity of 80% for prediabetes and 97.5% for diabetes, the optimal HbA1c cutoff points for prediabetes and diabetes were 5.6% and 6.4% in normal-weight, 5.7% and 6.5% in overweight, and 6.0% and 6.5% in an obese population. When the new HbA1c cutoff values were used, the agreement in obese subjects increased almost to the level in normal-weight subjects.

CONCLUSIONS

The poor agreement between HbA1c and OGTT criteria in an obese population can be significantly improved through increasing the HbA1c threshold for prediabetes.

Prevalance of gestational diabetes mellitus in patients with gestational transient thyrotoxicosis

OBJECTIVE

To investigate prevalence of gestational diabetes mellitus (GDM) in patients with gestational transient thyroxicosis (GTT).

METHODS

Fifty two patients with GTT and 100 age matched healthy pregnant women were included. Fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), LDL-cholesterol, HDL-cholesterol, triglyceride, thyrotrophin (TSH) and thyroid hormones were measured at thyrotoxic state in GTT patients and at 6-12th weeks of pregnancy in control group. Oral glucose tolerance test (OGTT) with 100 g glucose was performed and laboratory parameters were re-evaluated at 24-28th weeks of pregnancy in all subjects.

RESULTS

Mean age of patients with GTT was 28.46 ± 5.45 and control group was 27.78 ± 3.75(p = 0.085). Patients with GTT had significantly higher HbA1c, LDL-cholesterol and HDL-cholesterol at 6-12th weeks of pregnancy (p < 0.01, p < 0.01 and p = 0.034, respectively). TSH was negatively correlated with HbA1c and LDL-cholesterol in thyrotoxic state in GTT patients (r = -0.393, p < 0.001 and r = -0.293, p < 0.001, respectively). OGTT showed GDM in 7 (13.5%) GTT patients and 4 (4%) healthy pregnants (p = 0.047). HbA1c, LDL-cholesterol and HDL-cholesterol were higher in GTT patients compared to healthy pregnants also at 24-28th weeks of pregnancy (p < 0.001, p < 0.001 and p = 0.024).

CONCLUSION

Although GTT is known to be a transient state that can resolve spontaneously, it might have negative effect on carbohydrate metabolism like other causes of hyperthyroidism.

Altered fructosamine and lipid fractions in subclinical hypothyroidism

BACKGROUND

Thyroid function disorders lead to changes in the lipoprotein metabolism.

OBJECTIVES

To study the lipid and the glycaemic abnormalities in the subclinical hypothyroidism cases and to compare the same with the euthyroid, overt hypothyroid and the hyperthyroid subjects.

METHODOLOGY

Four groups, euthyroid (Group-I), hypothyroid (Group-II), subclinical hypothyroid (Group-III) and hyperthyroid (Group-IV), which consisted of 30 subjects each, of either sex, who were aged 25-55 years, underwent Fasting Plasma Glucose (FPG), fructosamine, lipid profile and total T3, T4 and TSH estimations. The subjects who were on lipid lowering or thyroid disorder drugs and known diabetics were excluded from the study.

RESULTS

In Group-III, all the lipid fractions were comparable to those of Group-II and they were significantly deranged, as compared to those of Group-I. The fructosamine levels were significantly higher in Group-II and Group-III (p<0.05), but the subclinical hypothyroid pool had statistically lower levels than the hypothyroid pool (376.63±54.73, 587.80±65.10). In the Group-IV patients, the LDL-C levels were significantly higher as compared to those in the euthyroid pool. The fructosamine levels were significantly lower in comparison with both the euthyroid and the hypothyroid pools (both in Groups-II and III). The FPG levels were higher in all the classes of the thyroid abnormalities (subclinical hypothyroidnot significant) but within the reference range of 70-100mg/dl.

CONCLUSION

Since the lipid derangement in subclinical hypothyroidism is on par with that in overt hypothyrodism, the subclinical hypothyroid cases also need to be treated similarly. The fructosamine values which are largely in excess of the FPG values, indicate a higher propensity to glycation and a decreased turnover of the proteins in the hypothyroid and the subclinical hypothyroid pools. Vice versa is true of the hyperthyroid pool. Fructosamine can be included in the thyroid work up of the patients to assess the metabolic function and the subsequent response after the initiation of the therapy.

Hemoglobin glycation index: a robust measure of hemoglobin A1c bias in pediatric type 1 diabetes patients

BACKGROUND

The hemoglobin glycation index (HGI) assesses biological variation in A1c after accounting for the effect of mean blood glucose (MBG). Previous studies minimized analytical variation that could mask biological variation and showed that HGI was consistent within individuals over time and positively associated with risk for microvascular complications. We tested the hypothesis that biological variation in A1c can be assessed by HGI calculated using routine MBG and A1c data obtained from a typical diabetes clinic.

METHODS

Self-monitored MBG and A1c were collected from charts of 202 pediatric type 1 diabetes patients attending 1612 clinic visits over 6 yr. Predicted A1c was calculated from the linear regression equation of A1c on MBG in the study population. HGI was calculated by subtracting predicted A1c from observed A1c. Patients were divided into low, moderate, and high HGI tertile groups.

RESULTS

Patients used 12 models of glucose meters. Download protocols varied with clinical practice over time. A1c was measured by multiple assays and laboratories. Despite this analytical heterogeneity, HGI was significantly different between individuals and correlated within individuals. MBG (mean ± SD, mg/dL) was similar in the low (186 ± 31), moderate (195 ± 28), and high (199 ± 42) HGI groups. A1c (%) was significantly different (p < 0.0001) in the low (7.6 ± 0.7), moderate (8.4 ± 0.7), and high (9.6 ± 1.1) HGI groups.

CONCLUSION

Biological variation in A1c is a robust quantitative trait that can be assessed using HGI calculated from routine clinic data. This suggests that HGI could be used clinically for more personalized assessment of complications risk.

Effects of subchronic coexposure to arsenic and endosulfan on the erythrocytes of broiler chickens: a biochemical study

Arsenic is a known global groundwater contaminant. The organochlorine insecticide endosulfan has gained significance as an environmental pollutant due to its widespread use in the control of many food- and non-food-crop-damaging insects. The adverse effects produced by arsenic or endosulfan alone in humans and animals are well documented, but very little is known about the consequences of their coexposure. We evaluated whether their simultaneous exposure can induce oxidative stress and affect antioxidative systems and certain membrane-bound enzymes in erythrocytes of broiler chickens. Day-old chicks were exposed to 3.7 ppm of arsenic via drinking water or 30 ppm of endosulfan-mixed feed or similarly coexposed to these in the same dose levels for 60 days. At term, the impact of their coexposure was assessed by evaluating lipid peroxidation (LPO), activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione-S-transferase (GST), different ATPases and acetylcholinesterase (AChE) in erythrocytes, serum glucose, and levels of glutathione (GSH) and glycosylated hemoglobin (GHb) in blood. LPO was increased with all of the treatments. Catalase was decreased with endosulfan and the coexposure, but not with arsenic, whereas GSH was decreased with arsenic and endosulfan, but not with the coexposure. All of the treatments increased SOD and GPx activities. GST activity was increased only in the coexposed birds. None of the treatments affected the activities of total ATPase and Mg2+-ATPase. Na+-K+-ATPase activity was decreased in the endosulfan-treated and the coexposed birds. All three exposures increased erythrocyte AChE activity. Endosulfan increased the serum glucose level and arsenic and endosulfan increased GHb levels, but these were not altered in the coexposed birds. Erythrocyte protein content was insignificantly decreased with these treatments. Overall, the effects of coexposure were not appreciably different from either of the agents, except on AChE, GSH, and glucose. The results do not reflect any specific type of interaction between these agents in chicken erythrocytes, but they do indicate that the coexposure induces a low level of oxidative stress, which is comparable to that induced by arsenic or endosulfan.

The role of selenium, vitamin C, and zinc in benign thyroid diseases and of selenium in malignant thyroid diseases: Low selenium levels are found in subacute and silent thyroiditis and in papillary and follicular carcinoma

BACKGROUND

Thyroid physiology is closely related to oxidative changes. The aim of this controlled study was to evaluate the levels of nutritional anti-oxidants such as vitamin C, zinc (Zn) and selenium (Se), and to investigate any association of them with parameters of thyroid function and pathology including benign and malignant thyroid diseases.

METHODS

This controlled evaluation of Se included a total of 1401 subjects (1186 adults and 215 children) distributed as follows: control group (n = 687), benign thyroid disease (85 children and 465 adults); malignant thyroid disease (2 children and 79 adults). Clinical evaluation of patients with benign thyroid disease included sonography, scintigraphy, as well as the determination of fT3, fT4, TSH, thyroid antibodies levels, Se, Zn, and vitamin C. Besides the routine oncological parameters (TG, TSH, fT4, ultrasound) Se was also determined in the cases of malignant disease. The local control groups for the evaluation of Se levels were taken from a general practice (WOMED) as well as from healthy active athletes. Blood samples were collected between 8:00 and 10:30 a.m. All patients lived in Innsbruck. Statistical analysis was done using SPSS 14.0. The Ho stated that there should be no differences in the levels of antioxidants between controls and thyroid disease patients.

RESULTS

Among the thyroid disease patients neither vitamin C, nor Zn nor Se correlated with any of the following parameters: age, sex, BMI, body weight, thyroid scintigraphy, ultrasound pattern, thyroid function, or thyroid antibodies. The proportion of patients with benign thyroid diseases having analyte concentrations below external reference cut off levels were 8.7% of cases for vitamin C; 7.8% for Zn, and 20.3% for Se. Low Se levels in the control group were found in 12%. Se levels were significantly decreased in cases of sub-acute and silent thyroiditis (66.4 +/- 23.1 microg/l and 59.3 +/- 20.1 microg/l, respectively) as well as in follicular and papillary thyroid carcinoma. The mean Se level in the control group was 90.5 +/- 20.8 microg/l.

CONCLUSION

The H0 can be accepted for vitamin C and zinc levels whereas it has to be rejected for Se. Patients with benign or malignant thyroid diseases can present low Se levels as compared to controls. Low levels of vitamin C were found in all subgroups of patients.

Oxidative stress: Does it play a role in the genesis of early glycated proteins?

Glycation and oxidative stress are two important processes known to play a key role in complications of many pathophysiological processes. The two traditional factors found to modulate the early glycation of proteins are the prevailing concentration of glucose and half life of the protein. But evidences in the literature have documented an increased glycated protein levels in some non-diabetic pathological states. So it stands to reason that hyperglycemia, while clearly the culprit in diabetes, is not the complete answer to the etiology of increased early glycated products in non-diabetic conditions. A common denominator in all these above mentioned non-diabetic pathological conditions is oxidative stress. Collective evidences from the literature reveal that malondialdehyde, reduced glutathione, vitamin C, vitamin E and drugs with antioxidant properties mitigate the process of protein glycation. Taking all the above factors into account, we hypothesis that oxidative stress either via increasing reactive oxygen species or by depleting the antioxidants may modulate the genesis of early glycated proteins in vivo.

Enhanced glycation of hemoglobin and plasma proteins is associated with increased lipid peroxide levels in non-diabetic hypertensive subjects

BACKGROUND

Accumulating evidences indicate that lipid peroxidation and protein glycation play a vital role in the pathogenesis of cardiovascular disease. The purpose of the present study was to evaluate the levels of lipid peroxides and glycated proteins in non-diabetic hypertensive patients and to assess the possible nexus between them, among these subjects.

METHODS

Thirty hypertensive patients and 25 normotensive subjects were enrolled in the present study. Lipid peroxides, glycated hemoglobin, and fructosamine levels were estimated in both groups.

RESULTS

Lipid peroxides, glycated hemoglobin, and fructosamine levels were significantly increased in hypertensive subjects in comparison with normotensive subjects. When partial correlation analysis was performed, malondialdehyde was significantly associated with glycated hemoglobin and fructosamine.

CONCLUSIONS

An increased glycation of proteins was found in non-diabetic hypertensive subjects. These data also support the premise that lipid peroxidation per se plays a role in glycation of hemoglobin and plasma proteins.

Increased plasma malondialdehyde and fructosamine in iron deficiency anemia: effect of treatment

Glycation and lipid peroxidation are spontaneous reactions that are believed to play a key role in the pathogenesis of many clinical disorders. Glycation of proteins is enhanced by elevated glucose concentrations. However, increased glycated hemoglobin levels have been documented in iron deficiency anemic patients without any history of diabetes. Collective evidences reveal that lipid peroxidation can modulate protein glycation. This study was undertaken to unravel the possible association of malondialdehyde and fructosamine in iron deficient anemic patients and to observe the possible alteration in malondialdehyde and fructosamine levels in these patients after one month supplementation with iron. Twenty non-diabetic anemic patients and 16 age-matched healthy subjects were enrolled for this study. Plasma lipid peroxides, fasting glucose, fructosamine, iron, ferritin and hemoglobin were analyzed in both the groups. Partial correlation analysis was performed to predict the independent association of malondialdehyde and fasting glucose on fructosamine. In anemic patients, while fructosamine and malondialdehyde levels were found to be significantly increased, hemoglobin, iron and ferritin levels decreased significantly when compared to before treatment. Fructosamine was found to have a significant positive correlation with malondialdehyde even after nullifying the effect of glucose. After one month supplementation with iron, both fructosamine and malondialdehyde levels decreased significantly when compared to before treatment. There was a significant increase in iron, ferritin and hemoglobin levels in anemic patients after one month of treatment. In conclusion, an increased level of fructosamine and malondialdehyde was found in anemic patients. These data suggest that fructosamine levels are closely associated with malondialdehyde concentrations in iron deficient anemic patients.

Attenuation of oxidative stress in plasma and tissues of rats with experimentally induced hyperthyroidism by caffeic acid phenylethyl ester

Increased oxidative stress with high free radical generation has been described previously in animal models of hyperthyroidism. The present study was designed to investigate the protective effects of caffeic acid phenylethyl ester (CAPE) on oxidative damage in rats with experimentally induced hyperthyroidism. The study was conducted on 32 male Sprague-Dawley rats. The experimental animals were divided into four groups (control, CAPE alone, hyperthyroidism, and hyperthyroidism + CAPE). Hyperthyroidism was induced by intraperitoneal administration of 0.3 mg/kg/day L-thyroxine for 4 weeks. CAPE (10 micro g/kg) was administered intraperitoneally for 4 weeks. At the end of the experimental period, blood samples and various organs (liver, heart and brain) of rats were taken for the determination of thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), oxidized glutathione, vitamin C and superoxide dismutase (SOD) levels and concentrations of triiodothyronine (T3), thyroxine (T4) and thyroxine-stimulating hormone (TSH). Our results indicate that TBARS, oxidized glutathione, SOD levels and concentrations of T3 and T4 were higher in plasma and tissues of the hyperthyroid group compared to controls. Vitamin C, GSH and TSH levels were decreased significantly in the hyperthyroid group when compared to the control group. CAPE treatment decreased the elevated TBARS, SOD, T3 and T4 levels and increased the lowered GSH, vitamin C and TSH levels to control levels in rats with hyperthyroidism. In conclusion, our results indicate that CAPE is beneficial as a protective agent against oxidative stress induced by hyperthyroidism in rats. The protection is probably due to multiple mechanisms involving free radical scavenger properties, attenuating lipid peroxidation and increasing the antioxidant status.

Increased plasma malondialdehyde and fructosamine in anemic H pylori infected patients: Effect of treatment

AIM: To unravel the possible association of malon-dialdehyde (MDA) and fructosamine in anemic H pylori infected patients and to observe the alteration in MDA and fructosamine levels in these patients after treatment for one month.

METHODS: Fructosamine, MDA and glucose were estimated in 22 anemic H pylori infected patients and 16 healthy controls. Hematological parameters were also evaluated in both the groups using Sysmex-K-100 automated cell counter. The H pylori infected patients were randomly divided into two groups. H pylori infected patients in GroupIreceived both iron supplementation and anti-H pylori therapy, while patients in Group II received only iron supplementation. All the biochemical and hematological parameters were estimated after one month of treatment.

RESULTS: In anemic H pylori infected patients, while MDA (5.41 ± 2.16 vs 2.26 ± 0.50; P < 0.05) and fructosamine (2.64 ± 0.93 vs 1.60 ± 0.35; P < 0.05) were significantly increased, iron (32.72 ± 14.93 vs 110.25 ± 26.58; P < 0.05), hemoglobin (6.9 ± 2.6 vs 12.66 ± 0.74; P < 0.05) and ferritin (28.82 ± 16.27 vs 140.43 ± 30.72; P < 0.05) levels were significantly decreased compared with the controls. With partial correlation analysis, fructosamine was found to have a significant positive correlation with MDA. In GroupI, while MDA level decreased significantly (3.11 ± 1.73 vs 5.50 ± 2.46; P < 0.05), there was a significant increase in iron (84.09 ± 29.51 vs 36.09 ± 17.81; P < 0.05), hemoglobin (10.40 ± 1.11 vs 7.42 ± 1.90; P < 0.05) and ferritin (116.91 ± 63.34 vs 30.46 ± 17.81; P < 0.05) levels after one month. There was no significant change in the levels of fructosamine in groupIafter treatment. Similarly, no significant alterations were noted in the levels of MDA, fructosamine, hemoglobin or ferritin in Group II patients after one month of treatment.

CONCLUSION: An increased level of fructosamine and MDA was found in anemic H pylori infected patients. Present data supports the premise that lipid peroxides per se do play a role in the glycation of plasma proteins. Furthermore, the findings from this study indicate that treatment for both anemia and H pylori infections is required for lowering the levels of lipid peroxides in these patients.

Increased glycation of hemoglobin and plasma proteins in normotensive, non-diabetic obese Indian subjects: putative role of lipid peroxides

BACKGROUND

Glycation and lipid peroxidation are spontaneous reactions believed to contribute to the pathogenesis of many clinical disorders. The purpose of the present study was to evaluate the levels of lipid peroxides and glycated proteins in normotensive, non-diabetic obese Indian subjects and to assess possible associations between them.

METHODS

A total of 28 obese male subjects and 20 non-obese subjects were included in the present study. Whole blood glycated hemoglobin, plasma lipid peroxides and fructosamine levels were estimated in both groups.

RESULTS

Lipid peroxides, glycated hemoglobin and fructosamine levels were significantly higher in obese subjects in comparison with non-obese subjects. We also found a significant association between malondialdehyde and body mass index (r=0.424, p=0.025). Partial correlation analysis revealed that malondialdehyde was significantly correlated with glycated hemoglobin (r=0.590, p=0.01) and fructosamine (r=0.442, p=0.021) after controlling for glucose.

CONCLUSIONS

Increased glycation of proteins was found in normotensive, non-diabetic obese Indian subjects. These data also support the premise that lipid peroxides per se play a role in the glycation of hemoglobin and plasma proteins.

LDL oxidation is associated with increased blood hemoglobin A1c levels in diabetic patients

AIM

To investigate whether levels of blood HbA1c in diabetic patients are associated with susceptibility of LDL to oxidation.

METHODS

LDL was separated from blood of 40 diabetic patients with known blood glucose and HbA1c levels. The tendency to undergo lipid peroxidation was assessed via lag time required for initiation of LDL oxidation. HbA1c formation was measured in vitro following incubation of red blood cell (RBC) hemolysate for 3 months with increasing concentrations of glucose in the absence or presence of LDL or oxidized LDL.

RESULTS

Lag time for copper-induced LDL oxidation was twice as long in normal subjects compared to diabetic patients. Correlation analyses between LDL oxidation lag time and HbA1c blood levels revealed an R value of 0.74. Incubation of RBC hemolysate with high glucose concentration (up to 400 mg/dl) resulted in increased blood HbA1c concentration by up to 107%. Addition of LDL to this hemolysate over a period of 3 months resulted in LDL oxidation and an increase in HbA1c levels by up to 168%. Similarly, addition of oxidized LDL to the hemolysate increased HbA1c by up to 240%.

CONCLUSIONS

Increased tendency of LDL to undergo lipid peroxidation in diabetic patients contributes to increased levels of blood HbA1c, mainly in those with HbA1c<7.3.

Evidence for the role of lipid peroxides on glycation of hemoglobin and plasma proteins in non-diabetic asthma patients

BACKGROUND

Collective evidences reveal that malondialdehyde (MDA), reduced glutathione (GSH) and ascorbic acid can modulate protein glycation. We investigated the concentrations of MDA, GSH, ascorbic acid and protein glycation in asthma patients to delineate the possible association among these parameters.

METHODS

Blood was collected from 18 asthma patients and 16 age and sex matched control subjects. Glycated hemoglobin (HbA1C), GSH, MDA, vitamin C, fructosamine and glucose were assessed in both groups. The effect of H2O2 on glycation of hemoglobin was studied by incubating normal healthy erythrocytes with either 5 or 50 mmol/l glucose concentration.

RESULTS

Plasma of asthma patients revealed significantly higher concentrations of lipid peroxides and fructosamine concentrations than the matched controls. Glycated hemoglobin concentrations were also found to be significantly increased. Ascorbic acid and GSH concentrations were decreased significantly in the test group when compared with the healthy control group. When the effects of fasting glucose, GSH and ascorbic acid on the concentrations of HbA1C and fructosamine were refuted by partial correlation analysis, MDA was found to be a significant determinant of HbA1c and fructosamine in patients with asthma. The in vitro model with human erythrocytes showed an enhancement of protein glycation by H2O2.

CONCLUSION

An increased glycation of proteins was found in asthma patients. These data also support the premise that lipid peroxides per se do have a role to play in glycation of hemoglobin and plasma proteins.

Reassessing the increased glycation of hemoglobin in nondiabetic chronic renal failure patients: a hypothesis on the role of lipid peroxides

BACKGROUND

Glycated hemoglobin (HbA(1C)) is considered clinically useful for assessing long-term integrated control of blood glucose in diabetes. However, an increased HbA(1C) concentration has been documented in chronic renal failure (CRF) patients without any history of diabetes. Collective evidences reveal that lipid peroxidation (MDA) can modulate protein glycation. We evaluated the relationship between glycated hemoglobin (HbA(1C)) and lipid peroxidation in non-diabetic CRF patients.

METHODS

Twenty-eight nondiabetic CRF and 23 age- and sex-matched healthy subjects were enrolled for this study. Plasma urea, creatinine, lipid peroxides, fasting glucose and HbA(1C) were analyzed in both the groups. The in-vitro effect of MDA on glycation of hemoglobin was studied by incubating healthy erythrocytes with either 5 or 50 mmol/l glucose concentration.

RESULTS

The percentage of HbA(1C) concentrations and plasma malondialdehyde (MDA) were significantly increased in CRF patients compared to control subjects. When the effects of uremia and blood glucose on the concentration of HbA(1C) was refuted by partial correlation analysis, MDA was found to be a significant determinant of HbA(1C) (r=0.41, p=0.04) in patients with renal failure. In-vitro incubation of RBC with glucose along with MDA was found to enhance the process of hemoglobin glycation.

CONCLUSION

Our results suggest that lipid peroxidation per se can contribute to glycation of hemoglobin, warranting extra-precaution in interpreting HbA(1C) as a measure of glycemic control in CRF.

Effect of lipid peroxides and antioxidants on glycation of hemoglobin: an in vitro study on human erythrocytes

BACKGROUND

Glycation and lipid peroxidation are two important processes known to play a key role in complications of many pathophysiological process. We sought to assess the possibility of an interaction between these processes in vitro and to examine the effect of lipoic acid and taurine on the glycation of hemoglobin and lipid peroxidation.

METHODS

Human erythrocytes in phosphate buffered saline (pH 7.4) were incubated with 5 or 50 mmol/l glucose. To study the effect of antioxidants on glycation of hemoglobin, erythrocytes were incubated with either lipoic acid or taurine and then exposed to glucose concentration of either 5 or 50 mmol/l. To clarify if lipid peroxides per se enhances the glycated hemoglobin level, an in vitro study was performed by incubating erythrocyte suspension containing either 5 or 50 mmol/l glucose with or without MDA. Lipid peroxides and glycated hemoglobin levels were determined in the glucose treated cells.

RESULTS

Glycated hemoglobin levels were higher in erythrocytes incubated with 50 mmol/l glucose concentrations than in erythrocytes incubated with 5 mmol/l glucose. The increase in glycated hemoglobin levels was blocked significantly when erythrocytes were pretreated with either lipoic acid or taurine. Both the antioxidants used in the present study markedly reduced the MDA levels. The level of glycated hemoglobin in erythrocyte incubated in the presence of MDA was increased significantly when compared to erythrocyte incubated with glucose alone.

CONCLUSIONS

Lipid peroxides per se may have a role to play in glycation of hemoglobin and antioxidants (lipoic acid and taurine) can partially inhibit the formation of glycated hemoglobin by lowering the levels of lipid peroxides.