Inorganic phosphate accelerates hemoglobin A1c synthesis

The effects of inorganic phosphate (Pi), 2,3-diphosphoglycerate (2,3-DPG) and glucose-6-phosphate (G-6-P) on labile and stable hemoglobin A1c (HbA1c) synthesis were studied. After a 75 gram oral glucose administration, the rate of labile or stable HbA1c synthesis decreased in parallel to the decrease in plasma Pi concentrations. In in vitro incubations of red blood cell suspensions or hemoglobin preparations with glucose, Pi proportionally increased the rate of labile or stable HbA1c synthesis. The increase in 2,3-DPG caused by Pi explained only one fiftieth of the increased rate of labile HbA1c synthesis, and G-6-P did not affect HbA1c synthesis. The kinetic analysis of the effect of Pi showed the unchanged rate constant [K1], the decreased rate constant [K-1], and the increased rate constant [K2]. Based on these data it is concluded that Pi in its physiological range directly increases hemoglobin glycation by decreasing labile HbA1c dissociation and accelerating the Amadori rearrangement for stable HbA1c synthesis, and that Pi should be taken into account when using HbA1c to evaluate diabetic control.     

Limited synthesis of labile hemoglobin A1 in vivo and in vitro by the preexisting hemoglobin A1 in diabetic subjects

The synthesis of labile hemoglobin A1 in vivo was studied in subjects with non-insulin dependent diabetes mellitus, impaired and normal glucose tolerance. The labile hemoglobin A1 index defined as delta labile hemoglobin A1 divided by delta plasma glucose at 30 min after oral glucose load, representing the rate of labile hemoglobin A1 synthesis in vivo, was low in diabetic subjects and high in normal subjects, showing an inverse correlation with the amount of preexisting hemoglobin A1. The study on the synthesis of labile hemoglobin A1 in vitro showed a lower initial rate of synthesis and a smaller increase in labile hemoglobin A1 at saturation in red blood cells from diabetic subjects with a relatively large amount of preexisting hemoglobin A1, as opposed to red blood cells from normal subjects. Although the further study is necessary in which delta plasma glucose levels are kept relatively constant in each of 3 groups by glucose-clamp methods, our data suggest that the synthesis of labile hemoglobin A1 is limited in vivo and in vitro in diabetic subjects by the preexisting hemoglobin A1 due to the saturability of its synthesis.     

A Novel Glycated Hemoglobin A1c-Lowering Traditional Chinese Medicinal Formula,Identified by Translational Medicine Study

Diabetes is a chronic metabolic disorder that has a significant impact on the health care system. The reduction of glycated hemoglobin A1c is highly associated with the improvements of glycemic control and diabetic complications. In this study, we identified a traditional Chinese medicinal formula with a HbA1c-lowering potential from clinical evidences. By surveying 9,973 diabetic patients enrolled in Taiwan Diabetic Care Management Program, we found that Chu-Yeh-Shih-Kao-Tang (CYSKT) significantly reduced HbA1c values in diabetic patients. CYSKT reduced the levels of HbA1c and fasting blood glucose, and stimulated the blood glucose clearance in type 2 diabetic mice. CYSKT affected the expressions of genes associated with insulin signaling pathway, increased the amount of phosphorylated insulin receptor in cells and tissues, and stimulated the translocation of glucose transporter 4. Moreover, CYSKT affected the expressions of genes related to diabetic complications, improved the levels of renal function indexes, and increased the survival rate of diabetic mice. In conclusion, this was a translational medicine study that applied a “bedside-to-bench” approach to identify a novel HbA1c-lowering formula. Our findings suggested that oral administration of CYSKT affected insulin signaling pathway, decreased HbA1c and blood glucose levels, and consequently reduced mortality rate in type 2 diabetic mice.     

Increased insulin-insensitive glucose transport in polymorphonuclear leukocytes from non-insulin-dependent diabetic patients.

We studied the transport rate of a non-metabolizable hexose analogue, 3-O-methyl-D-glucose, in polymorphonuclear leukocytes (insulin-insensitive cells) from patients with untreated non-insulin-dependent diabetes mellitus. The mean glucose transport rate was significantly elevated in the diabetic patients compared with healthy controls (13.3 +/- 3.7 vs 10.4 +/- 2.5 fl/cell.sec, mean +/- SD, p less than 0.01). In the diabetic subjects, glucose transport rates were positively correlated with HbA1c levels (r = 0.563, p less than 0.01) but had no relations with ambient plasma glucose concentrations. Short-term incubation with 20 mM D-glucose had no effect on glucose transport in those cells. When glucose transport rates, HbA1c and fasting plasma glucose levels were simultaneously measured at weekly intervals over a four-week period in three diabetic subjects, the alterations in transport rates generally paralleled the changes observed in HbA1c levels rather than plasma glucose concentrations. It can be concluded that unlike insulin-sensitive cells such as adipocytes and muscle, glucose transport in human polymorphonuclear leukocytes, which are insulin insensitive cells, is increased in patients with non-insulin-dependent diabetes mellitus. Long-term, not short-term, derangement of glucose metabolism seems to be associated with increased glucose transport rate found in those patients.     

Prediction of Glycated Hemoglobin Levels at 3 Months after Metabolic Surgery Based on the 7-Day Plasma Metabolic Profile

Metabolic surgery has been shown to provide better glycemic control for type 2 diabetes than conventional therapies. Still, the outcomes of the surgery are variable, and prognostic markers reflecting the metabolic changes by the surgery are yet to be established. NMR-based plasma metabolomics followed by multivariate regression was used to test the correlation between the metabolomic profile at 7-days after surgery and glycated hemoglobin (HbA1c) levels at 3-months (and up to 12 months with less patients), and to identify the relevant markers. Metabolomic profiles at 7-days could differentiate the patients according to the HbA1c improvement status at 3-months. The HbA1c values were predicted based on the metabolomics profile with partial least square regression, and found to be correlated with the observed values. Metabolite analysis suggested that 3-Hydroxybutyrate (3-HB) and glucose contributes to this prediction, and the [3-HB]/[glucose] exhibited a modest to good correlation with the HbA1c level at 3-months. The prediction of 3-month HbA1c using 7-day metabolomic profile and the suggested new criterion [3-HB]/[glucose] could augment current prognostic modalities and help clinicians decide if drug therapy is necessary.     

Localization of the putative precursor of Alzheimer''s disease-specific amyloid at nuclear envelopes of adult human muscle.

Cloning and sequence analysis revealed the putative amyloid A4 precursor (pre-A4) of Alzheimer's disease to have characteristics of a membrane-spanning glycoprotein. In addition to brain, pre-A4 mRNA was found in adult human muscle and other tissues. We demonstrate by in situ hybridization that pre-A4 mRNA is present in adult human muscle, in cultured human myoblasts and myotubes. Immunofluorescence with antipeptide antibodies shows the putative pre-A4 protein to be expressed in adult human muscle and associated with some but not all nuclear envelopes. Despite high levels of a single 3.5-kb pre-A4 mRNA species in cultured myoblasts and myotubes, the presence of putative pre-A4 protein could not be detected by immunofluorescence. This suggests that putative pre-A4 protein is stabilized and therefore functioning in the innervated muscle tissue but not in developing, i.e. non-innervated cultured muscle cells. The selective localization of the protein on distinct nuclear envelopes could reflect an interaction with motor endplates.     

Fluctuation between Fasting and 2-H Postload Glucose State Is Associated with Chronic Kidney Disease in Previously Diagnosed Type 2 Diabetes Patients with HbA1c ≥ 7%

Objective

To investigate how the glucose variability between fasting and a 2-h postload glucose state (2-h postload plasma glucose [2hPG]-fasting plasma glucose [FPG]) is associated with chronic kidney disease (CKD) in middle-aged and elderly Chinese patients previously diagnosed with type 2 diabetes.

Design and Methods

This cross-sectional study included 1054 previously diagnosed type 2 diabetes patients who were 40 years of age and older. First, the subjects were divided into two groups based on a glycated hemoglobin (HbA1c) value of 7%. Each group was divided into two subgroups, with or without CKD. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was used to estimate the glomerular filtration rate (GFR). CKD was defined as eGFR<60 mL/min/1.73 m². Multiple linear regression analysis was used to estimate the association between the 2hPG-FPG and eGFR. The 2hPG-FPG value was divided into four groups increasing in increments of 36 mg/dl (2.0 mmol/L): 0–72, 72–108, 108–144 and ≥144 mg/dl, based on the quartiles of patients with HbA1c levels ≥7%; then, binary logistic regression analysis was used to investigate the association between 2hPG-FPG and the risk of CKD.

Results

In the patients with HbA1c levels ≥7%, the 2hPG-FPG was significantly associated with decreased eGFR and an increased risk of CKD independent of age, gender, body mass index (BMI), systolic blood pressure (BP), diastolic BP, smoking, and drinking, as well as fasting insulin, cholesterol, triglyceride, and HbA1c levels. The patients with 2hPG-FPG values ≥144 mg/dl showed an increased odds ratio (OR) of 2.640 (P = 0.033). Additionally, HbA1c was associated with an increased risk of CKD in patients with HbA1c values ≥7%.

Conclusions

The short-term glucose variability expressed by 2hPG-FPG is closely associated with decreased eGFR and an increased risk of CKD in patients with poor glycemic control (HbA1c≥7%).     

Effect of iron deficiency anaemia over glycated hemoglobin in non-diabetic women

Background: Glycated hemoglobin (HbA1c) is a form of hemoglobin bound to glucose and used as an index of glycaemic control reflecting glucose levels of the previous three months. Iron deficiency anemia (IDA) is the commonest form of anemia that affects HbA1c. Reports on the effects of IDA on HbA1c levels are inconsistent in India. Therefore, the study correlated the HbA1c and IDA in non-diabetic female patients. Methods: A correlative study between HbA1c and IDA was carried out at the Department of Biochemistry, A. J. Institute of Medical Sciences, Mangaluru, India. A total of 50 non-diabetic female patients, aged between 20-50 years, with decreased levels of Hb, MCV and MCHC were selected. Their ferritin levels were determined by ELISA method to confirm IDA. Forty confirmed iron-deficient samples whose serum ferritin levels were <90 pg/dL, were tested for HbA1c levels by nephelometry method. Results: HbA1c correlated positively with serum ferritin, Hb, MCV, MCH and MCHC (P<0.05). There was a significant decrease in mean value of HbA1c in those with severe anemia (4.50±0.34) compared to those with moderate anemia (5.18±0.35) (P<0.001). Conclusion: Results showed positive correlation of HbA1c with ferritin and hemoglobin. Therefore, iron status should be considered during the interpretation of the HbA1c concentrations in diabetes mellitus.     

Routine enzymes in the monitoring of type 2 diabetes mellitus

We examined the relationships of glucose and HbA1c levels with the routinely screened serum enzyme activities in type 2 diabetes mellitus, and we designed an in vitro study to evaluate the direct effect of glucose levels on enzyme activities. The study was performed on a consecutive series of outpatients with type 2 diabetes who were followed up at Dicle University Medical Faculty Hospital from May 2009 to May 2010 for the first time. Effects of aspartate transaminase, aminotransferase, gamma‐glutamyl transferase (GGT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) activities, glucose and HbA1c levels and in vitro glucose (492, 287, 184, 131, 82 mg dl⁻¹, respectively) on enzymes were determined. The patients were categorized on the basis of glucose and HbA1c levels and grouped according to a range of values. In patients with high HbA1c levels (>10.1%), ALP, GGT activities and creatine kinase (CK)‐MB/CK (p = 0.008, 0.026, 0.014) ratio were increased significantly when compared with those in the control group. In patients with high glucose levels (>200 mg dl⁻¹), ALP, GGT activities and CK‐MB/CK ratio (p = 0.003, 0.001, 0.001) were increased significantly when compared with those in the control group. Glucose, which was added to serum in different concentrations in vitro, did not directly affect enzyme activities such as ALP, GGT and CK. We concluded that increased glucose levels could damage the liver and the heart muscle cells. Monitoring of blood glucose levels is a more valuable parameter than monitoring HbA1c in the momentary evaluation of diabetes. Copyright © 2011 John Wiley & Sons, Ltd.     

Studies on subfractions of hemoglobin A1b and hemoglobin A1c in diabetic subjects

Hemoglobin (Hb) obtained from the hemolysate of normal subjects and diabetic patients was separated into HbA1a1, HbA1a2, HbA1b, HbA1c and HbA0 (major Hb) by Bio-Rex 70 cation exchange column chromatography. The glycosylated Hbs were further separated reproductively by cation exchange high performance liquid chromatography (HPLC), using 50 mM sodium phosphate buffer pH 5.80 with 0-0.2 M NaCl linear gradient system. HbA1b and HbA1c were separated into two subfractions (HbA1b1 and HbA1b2) and three subfractions (HbA1c1, HbA1c2, HbA1c3), respectively. The percentages of each subfraction except HbA1c1 in diabetic patients were significantly higher than those in normal subjects. Furthermore, HbA1c1, HbA1c2 and HbA1c3 correlated well with fasting blood glucose levels in the prior 5 month period, while subfractions in HbA1b revealed no significant correlation with blood glucose levels. The percentages of each subfraction of HbA1c in patients either with diabetic cataracts or with diabetic neuropathy were almost the same as those in the patients without complications. However, the percentages of each of the three groups were markedly higher than those of the normal subjects. These results suggest that glycosylation of hemoglobin in diabetic patients may be increased in various sites of the molecule in parallel with the blood glucose levels during the preceding 4-5 months.     

Antidiabetic zinc(II)-N-acetyl-L-cysteine complex: evaluations of in vitro insulinomimetic and in vivo blood glucose-lowering activities

The diabetic state is known to induce oxidative stress in its mechanism, which in turn is responsible for the complications of diabetes mellitus (DM). Recently, we found that Zn(II) complexes have in vitro insulinomimetic and in vivo blood glucose-lowering activities. During our study on the development of new Zn(II) complexes with antioxidative ligands involving L-cysteine, L-cysteine-methylester, and N-acetyl-L-cysteine (nac), we found a new (N-acetyl-L-cysteinato)Zn(II) (Zn(nac)) complex by evaluating of both its in vitro insulinomimetic and in vivo potencies. The insulinomimetic activity of Zn(nac) with respect to the inhibition of free fatty acid release in isolated rat adipocytes treated with epinephrine was higher than that of a well-known insulinomimetic VOSO4, being equivalent to that of ZnSO4. The blood glucose level of hyperglycemic KK-Ay mice with type 2 DM was reduced by daily intraperitoneal injections of Zn(nac) for 28 days. Their serum insulin, HbA1c, TCHO, and UN levels were remarkably decreased, indicating that Zn(nac) improved the insulin resistance of the mice. The improvement of DM by Zn(nac) was also confirmed by the oral glucose tolerance test. In conclusion, Zn(nac) complex is proposed to attenuate both hyperglycemia and hyperinsulinemia in KK-Ay mice by decreasing serum insulin, HbA1c, UN, and TCHO levels.     

妊娠糖尿病患者血清HbA1c与CRP水平的相关性分析

目的:为明确妊娠期糖尿病(gestational diabetes mellitus,GDM)患者血清糖化血红蛋白(glycosylated hemoglobin,Hb A1c)与C反应蛋白(C-reactive protein,CRP)的关系,本研究检测了GDM患者血糖、血清Hb A1c与CRP水平,并对Hb A1c与CRP的相关性进行了分析。方法:以68例2015年4月至2017年4月于我院诊治的GDM孕妇为研究对象,所有患者均符合《妇产科学》中关于GDM的诊断标准,另选取68例正常孕妇为对照组。采用葡萄糖氧化酶法检测血糖水平(空腹血糖及餐后2 h血糖水平),采用免疫凝集法检测和比较两组血清糖化血红蛋白(HbA1c)水平,采用免疫透射比浊法检测血清C反应蛋白(CRP)水平,并分析HbA1c与CRP的相关性。结果:GDM组患者空腹血糖(fasting plasma glucose,FPG)、2 h血糖(plasma glucose,PG)、血清HbA1c和CRP水平均显著高于正常组(P0.05),GDM患者血清Hb A1c和CRP水平呈显著正相关关系(r=0.654,P0.05)。结论:GDM患者血清HbAlC和CRP水平相较于正常孕妇有显著提高,且二者呈显著的正相关关系,二者联合检测可能作为GDM早期诊断的筛查的重要参考指标。     

Growth and Glucose Repression Are Controlled by Glucose Transport in Saccharomyces cerevisiae Cells Containing Only One Glucose Transporter

A set of Saccharomyces cerevisiae strains with variable expression of only the high-affinity Hxt7 glucose transporter was constructed by partial deletion of the HXT7 promoter in vitro and integration of the gene at various copy numbers into the genome of an hxt1-7 gal2 deletion strain. The glucose transport capacity increased in strains with higher levels of HXT7 expression. The consequences for various physiological properties of varying the glucose transport capacity were examined. The control coefficient of glucose transport with respect to growth rate was 0.54. At high extracellular glucose concentrations, both invertase activity and the rate of oxidative glucose metabolism increased manyfold with decreasing glucose transport capacity, which is indicative of release from glucose repression. These results suggest that the intracellular glucose concentration produces the signal for glucose repression.     

Effects of human diabetic serum on the in vitro development of early somite rat embryos

High levels of glucose, beta-hydroxybutyrate (B-HOB), and acetoacetate are known to have embryotoxic and teratogenic effects on rat embryos in culture, especially when added concomitantly to the culture medium. We studied the effects of human serum from different types of diabetes mellitus on the in vitro development of 10 1/2-day-old rat embryos cultured for 48 hours. We used serum from type I diabetes with and without ketoacidosis and type II diabetes either untreated or treated with insulin or with daonil. Type I diabetes without ketoacidosis increased the rate of malformations to 27% vs. 11% in controls. Serum from type I diabetes with ketoacidosis further increased the malformation rate to 44%. The rate of malformations induced by serum of type II diabetes was dependent on the treatment. It was relatively low among embryos cultured on serum from untreated (16%) or treated with daonil (19%) and rose to 27% among embryos cultured on serum from type II diabetes treated with insulin. No significant correlation was found between the rate of malformations and the concentrations of glucose, B-HOB, acetoacetate, and HbA1c in all diabetic sera except serum from type I diabetes with ketoacidosis. We may therefore conclude that for most types of diabetes in humans, neither the high blood glucose concentrations nor the high levels of ketone bodies seem to be the main reason for the high rate of malformations. However, we used cultured rat embryos, and the effects on the human embryo may be different. The results of studies on various experimental animal models in diabetes teratogenicity seem to have only partial relevance to the human situation.     

Glycolipid pattern and glycosilated hemoglobin (HbA 1) in a group of arteriosclerotic subjects

Total glycosilated haemoglobin (HbA1) concentration, serum triglyceride and cholesterol levels were measured in 55 arterio sclerotic patients classified in three groups: (A) normal, (B) borderline and (C) chemical diabetics according to their OGTT results. HbA1 values were high only in group C. In these patients the HbA1 concentrations correlated to the serum glucose peaks and serum triglyceride levels. Therefore we believe that the HbA1 concentration can be considered an index of the degree of carbohydrate imbalance in arteriosclerotic patients who frequently have high triglyceride levels and carbohydrate intolerance.     

Aspects of adipose-tissue metabolism in foetal lambs.

1. The mean volume of adipocytes, the rates of fatty acid and acylglycerol glycerol synthesis from various precursors (in vitro), the rates of oxidation of acetate and glucose (in vitro) and the activities of lipoprotein lipase and various lipogenic enzymes were determined for perirenal adipose tissue from foetal lambs during the last month of gestation. 2. The fall in the rate of growth of perirenal adipose tissue during the last month of gestation is associated with a diminished capacity for fatty acid synthesis and lipoprotein lipase activity, but no change in the rate of acylglycerol glycerol synthesis was observed. There was no fall in the activities of cytosolic acetyl-CoA synthetase or the NADP-linked dehydrogenases, suggesting that the decrease in the rate of fatty acid synthesis was due to an impairment at the level of acetyl-CoA carboxylase or fatty acid synthetase. 3. The rate of fatty acid synthesis from acetate was greater than that from glucose. The rate of fatty acid synthesis from glucose per adipocyte of foetal lambs was similar to that of young sheep. The characteristic metabolism of adipose tissue of the adult sheep is thus present in the foetus, despite the relatively large amounts of glucose in the foetal 'diet'.     

Pentosidine plasma levels and relation with metabolic control in diabetic patients.

Levels of plasma pentosidine, a well-known AGE, were measured in type 2 diabetic patients in varying states of metabolic control to verify possible relationships between this parameter and traditional metabolic control parameters such as HbA1c and plasma glucose levels. At baseline, mean values of fasting plasma glucose, HbA1c and pentosidine were significantly higher in diabetic patients than those of controls, confirming patients' poor glycemic control. After ten months, patients with good metabolic control achieved showed near-normal HbA1c levels and reduced but not normalized pentosidine levels. Significant differences were found in the mean percentage decrease in the parameters. Regarding linear correlation, HbA1c levels only showed a positive relationship with plasma glucose values at baseline. Patients affected by chronic complications showed higher levels of pentosidine than those without complications. Thus, pentosidine plasma levels may be used to evaluate very long-term metabolic control in diabetic patients. In addition, a period of ten months of acceptable metabolic control is not enough to normalize pentosidine levels in diabetics, thus emphasizing the need for a longer period of improved metabolic control to reduce both this parameter and the burden of chronic diabetic complications.     

Abolition by preventive action of calcitonin of vitamin D3-stimulated gluconeogenesis in rat kidney

The effects of vitamin D3, 1-alpha-OH D3 and calcitonin treatment on the rate of glucose synthesis in rat renal cortex slices were studied. The rate of glucose synthesis was significantly increased in animals treated with vitamin D3 and 1-alpha-OH D3 as compared to the control. The increase in the rat of glucose synthesis observed after vitamin D3 and 1-alpha-OH D3 treatment was abolished after administration of calcitonin in doses normalizing the serum calcium level. The obtained data point to a correlation between the serum calcium level observed in vivo and the ability to synthesize glucose measured in vitro in renal cortex slices.     

Relation between glycoprotein synthesis and carbohydrate metabolism in the small intestine mucosa. Effect of cholera enterotoxin

The regulatory properties of adenylate cyclase in small intestinal mucosa were investigated. Glucagon, epinephrine and isoproterenol failed to activate the cAMP synthesis; prostaglandin E1 caused a 2.8-fold, while cholera toxin-a 4.5-fold stimulation. The latter was not able to increase the rate of glucose synthesis from alanine in vitro, but increased markedly the in vivo incorporation of 14C-labeled alanine into the mucus glucosamine. Unlabeled glucosamine excretion was also enhanced 3-fold. This provides evidence for the involvement of glycolysis and gluconeogenesis enzyme systems in the mucosal glycoprotein synthesis. It was assumed that both metabolic pathways may play a common physiological role, namely, to convert carbohydrates and gluconeogenic precursors into the substrate for glucosamine synthesis which is thought to be a rate-limiting step in small intestinal mucus secretion.