Levels of serum sialic acid and thiobarbituric acid reactive substances in subjects with impaired glucose tolerance and type 2 diabetes mellitus

Cardiovascular disease is a common cause of death for diabetic patients. High sialic acid levels (SA) and increased oxidative stress are important factors for cardiovascular diseases. We aimed to research whether SA and thiobarbituric acid reactive substances (TBARS) levels are associated with the degree of the diabetic regulation and investigate if SA and TBARS levels can be controlled with the regulation of the blood glucose levels. A total of 179 subjects were included in the study. Three groups, which were comprised of subjects with type 2 diabetes mellitus (DM) (DM group [DMG], n=149), impaired glucose tolerance (IGT) (IGT group [IGTG], n=15), and normal oral glucose tolerance (NGT) (NGTgroup [NGTG], n=15) were constituted. Glucose, cholesterol, high-density lipoprotein (HDL) and glycated hemoglobin (HbA1C), SA, and TBARS were measured in the sera of the patients. SA and TBARS levels were significantly increased in subjects with type 2 DM (P<0.001 for both). SA concentrations showed significant correlation with triglycerides (r=0.229; P<0.05), fasting glucose (r=0.508; P<0.01), 2-hr postprandial glucose (r=0.455; P<0.01), and HbA1C (r=0.467; P<0.01), and there was a positive correlation between TBARS and HbA1C (r=0.251; P<0.01). Diabetic patients were found to have higher risk for inflammation and oxidative stress. The regulation of blood glucose levels may contribute to the decline of both SA and TBARS levels.     

Healing of diabetic foot ulcers in L-arginine-treated patients

Experimentally, we demonstrated the beneficial effects of L-arginine on regulation of hyperglycemia and dyslipidemia in experimental diabetes, in addition to a positive anti-aggregating effect in platelets in animals and humans. Here, the effect of L-arginine on foot ulcers from diabetic patients was studied. Three groups of diabetic patients were included: 11 patients without ulcer received neither treatment and served as controls. Eleven patients with diabetic ulcer received the standard treatment, this group served as diabetic control with diabetic ulcer. Eleven remain patients with diabetic ulcer received 10 mM L-arginine subcutaneously on the site of the wound. Biopsy with punch number 5 on wound site comprising both ulcerative and contiguous undamaged skin were performed in all patients with ulcerative lesions before any treatment. Patients with intact skin had biopsy performed with punch number 5 on external malleolar region of right lower limb. Biopsies were examined by light and confocal microscopy utilizing histochemical and immunohistochemical methods. Initial and final blood samples were collected to determine glucose, triglycerides, total cholesterol, glycated hemoglobin (HbA(1c)), low (LDL), and high density lipoproteins (HDL). Significant differences (P < 0.05) were observed between initial and final serum glucose levels for treated patients, and initial serum glucose levels between treated and control patients without diabetic ulcer. Glycated hemoglobin, triglycerides, cholesterol, and lipoprotein levels showed no significant changes. Eight patients treated with L-arginine reached total wound healing and the remaining three who abandoned the study because of change of residence showed relevant improvement. Histochemistry and immunohistochemistry methods have shown vascular impairment in both patients with diabetic ulcer (prior to treatment) and control patients without diabetic ulcer. Our observations strongly support efficacy of L-arginine for successful wound healing of diabetic ulcers.     

Rat tissue collagen modified by advanced glycation: correlation with duration of diabetes and glycemic control.

Collagenous proteins are especially prone to nonenzymatic glycation, because they contain several dibasic amino acid residues with free amino groups, have a very slow turnover rate, and are exposed to ambient levels of glucose. The aim of this study was to determine the time-dependent course of advanced glycation process in diabetic rats in relation to glycemic control and duration of diabetes, compared to age-matched controls. Immunochemical assay with antibodies to advanced glycation end products (AGE) was first developed to qualitatively detect and quantify the AGE formed in rat tendon and aortic collagen. Individual collagen samples were extracted by extensive pepsin and collagenase digestion. The amount of AGE was measured by competitive ELISA and results were expressed as AGE U/mg collagen. Diabetic rats showed a significant increase in AGE content in aortic collagen at 20 weeks (n = 6, 206.6 +/- 16.7 U/mg collagen) compared with that measured at 4 and 12 weeks (n = 6, 110 +/- 12.8 U/mg collagen, and n = 13, 184.9 +/- 12.3 U/mg collagen at 4 and 12 weeks, respectively; p < 0.001 between 20 weeks and 4 weeks; p < 0.01 between 20 weeks and 12 weeks). The amount of AGE in tendon collagen of diabetic rats increased from 1.9 +/- 0.38 U/mg at 4 weeks to 11.2 +/- 6.1 U/mg collagen at 20 weeks, p < 0.001. Considerable disparity was observed in the intensity of glycation between aortic and tendon collagen. AGE-content per mg of aortic collagen was several-fold to that found in tendon collagen (p < 0.001). To investigate the effect of glycemic control on the advanced glycation process, total aortic AGE-collagen content was compared between untreated diabetic rats (D; n = 13, 184.9 +/- 12.3 U/mg) and diabetic rats treated for 12 weeks with insulin (DI; n = 6, 133.9 +/- 10.7 U/mg), or phlorizin (DP; n = 6, 132.4 +/- 8.9 U/mg), or by a combination of insulin/phlorizin (DIP; n = 6, 124.3 +/- 6.5 U/mg). In spite of therapy used, all groups of diabetic animals had a significantly higher aortic AGE-collagen content than those in the nondiabetic control group (C: n = 8, 104.6 +/- 14.9 U/mg) of the same age (D, DI, DP, DIP vs. C, p < 0.001). Comparison between the mean levels of glycated hemoglobin (D: 5.62 +/- 0.38 % vs. C: 1.7 +/- 0.05%) and mean AGE levels in the studied group of animals yielded a very good exponential correlation (r = 0.89, p < 0.001). Glycation-derived late-stage collagen modification was detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and by immunoblotting confirmed to contain (an) AGE-structure(s). Our study provides strong immunochemical evidence of AGE formation in vivo during hyperglycemia, and of their temporal association with structural alterations of extracellular matrix proteins. The advanced glycation process is retarded and reduced in intensity, but not completely abolished, by glycemia regulation with, or independently of, insulin.     

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.     

Effects of OPB-9195, anti-glycation agent, on experimental diabetic neuropathy

BACKGROUND: Nonenzymatic glycation of neural proteins and their end-products (advanced glycation end-products, AGE) have been implicated in the pathogenesis of diabetic neuropathy. We need a development of effective ant-glycation agents for future clinical use. MATERIALS AND METHODS: We examined the effects of OPB-9195 (OPB), a new inhibitor of glycation, on the peripheral nerve structure and function in diabetic rats. Eight-week-old Wistar rats were made diabetic by streptozotocin (40 mg kg(-1), i.v.) and OPB (60 mg kg(-1) day(-1)) was given by gavage for 24 weeks. Age- and sex-matched normal Wistar rats were used for comparison. RESULTS: During the experimental period, OPB treatment did not affect the reduced body weight, elevated levels of blood glucose and glycated haemoglobin in diabetic rats. At the end of the experiment, delayed tibial motor nerve conduction velocity was significantly improved (by 60%) in treated diabetic rats, with reduction of serum AGE levels. Expression of immunoreactive AGE in the sciatic nerve was reduced in treated diabetic rats compared with those in untreated rats. Sciatic nerve (Na+, K+)-ATPase activity was also restored in treated diabetic rats. On the cross-sectioned sciatic nerves, positive cells with oxidative stress-related DNA damage, as expressed by 8-hydroxy-2'-deoxyguanosine, were less in the peripheral nerve of treated diabetic rats compared with those of untreated rats. CONCLUSION: The current study suggested that OPB is beneficial for the reduction of serum AGE and the prevention of diabetic neuropathy.     

Inhibition of in vitro pyrraline formation by L-arginine and polyamines

Glycation of biomolecules such as proteins, nucleic acids and lipids leading to the formation of advanced glycation end products (AGEs) may be a major contributor to the pathological manifestations of diabetes mellitus. Several studies have shown that the chemical inhibition of AGEs formation results in attenuation of diabetic complications. We tested the in vitro inhibition of pyrraline formation on bovine serum albumin and L-lysine by L-arginine and the polyamines putrescine, cadaverine, spermidine and spermine. Among the inhibitors, L-arginine and spermine potently inhibited pyrraline formation. This effect could be related to the presence of the guanidino group in L-arginine and four amino groups in spermine, but this inhibitory effect was also shown by putrescine, cadaverine and spermidine, suggesting that these natural compounds may have a novel therapeutic potential in preventing diabetic complications. A significant unexpected observation emerged when experiments were carried out with aminoguanidine. It showed increased absorbance produced by a non-identified compound whose peak appears at 285 nm, but this aspect remains to be investigated.     

Investigation of the mechanisms involved in the high-dose and long-term acetyl salicylic acid therapy of type I diabetic rats

Diabetes mellitus has been classified as a conformational disease because of changes induced in the structure and function of proteins due to hyperglycemia. In this study, we investigated the effect of high-dose and long-term use of acetyl salicylic acid (ASA) on the streptozotocin-induced diabetic rats as a model of type I diabetes, with consideration on the structure and/or function of proteins. The N-[methylnitrosocarbamoyl]-d-glucosamine (streptozotocin)-induced diabetic rats together with the normal rats were studied for 5 months with and without receiving 100 mg/kg ASA in drinking water. All rats were investigated from different aspects such as heat shock protein (HSP) 70 level, serum glucose and insulin concentration, advanced glycated end product (AGE) and glycated hemoglobin (HbA1c) formation, lipid profile, high-density lipoprotein (HDL) functionality (paraoxonase1 and lecithin cholesterol acyltransferase activities), and the antioxidant system. In addition, the in vitro effect of ASA on the structure of albumin as a model protein was studied in the presence of glucose by spectroscopic techniques such as fluorometry and circular dichroism. The results show that ASA therapy causes a decrease in the glucose level and AGE and HbA1c formation, improves the lipid profile, HDL functionality, and the antioxidant capacity, induces serum HSP70, and overall decreases mortality of diabetic rats in comparison with the group without treatment. The conformation of glycated bovine serum albumin is different from the native form, and ASA retains the conformation of this protein similar to the native. The improving effect of ASA on diabetic rats is mostly due to its role as a chemopreventive agent in the structural conservation and protection of proteins involved in diabetes pathogenesis.     

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.     

益气养阴活血法对糖尿病大鼠肝脏P450的影响及其与血糖血脂的关系

目的探讨益气养阴活血法对糖尿病大鼠肝脏P450的影响及与血糖血脂的关系。方法取大鼠55只,分为健康对照组,模型组,丹蛭降糖胶囊(DJC)高、低剂量组,吡格列酮组,除健康对照组外,其余动物给予高脂饲料喂养4周,按35 mg/kg,给大鼠腹腔注射链脲佐菌素(STZ)溶液1次,造模成功后,DJC高、低剂量组分别给予1.08 g·kg~(-1)·d~(-1)、0.54 g·kg~(-1)·d~(-1),吡格列酮组给予10 mg·kg~(-1)·d~(-1),模型组、健康对照组给予等量0.9%氯化钠注射溶液。均连续灌胃8周,留取肝脏,逆转录反应及实时荧光定量PCR检测大鼠肝脏组织β-actin、P450,取血测定血糖、血脂、糖化血红蛋白(HbA1c)。结果与正常组比较,模型组大鼠肝脏P450表达明显升高(P0.01),予DJC后显著抑制了P450的过高表达,与模型组比较,差异有统计学意义(P0.01)。大鼠造模后血糖、血脂(TG)、HbA1c明显升高(P0.01),予DJC后,高、低两组血糖、血脂(TG)、HbA1c显著下降(P0.01或P0.05),疗效与吡格列酮近似。P450与血糖、HbA1c相关分析显示,均呈显著正相关(P0.01);P450与血脂各项指标均无明显相关性。结论具有益气养阴活血作用的丹蛭降糖胶囊对糖尿病大鼠肝脏P450酶活性有显著的抑制作用,有良好的降低血糖和血脂的作用,同时肝脏P450含量与血糖具有一定的相关性。     

Effect of succinic acid monoethyl ester on hemoglobin glycation and tail tendon collagen properties in type 2 diabetic rats

Succinic acid monoethyl ester (EMS) was recently proposed as an insulinotropic agent for the treatment of type 2 diabetes. The aim of the study was to investigate the effect of EMS and metformin administration on tail collagen content and its characteristics in streptozotocin–nicotinamide-induced type 2 diabetic rats. EMS was administered intraperitoneally for 30 days to normal and diabetic rats. In the diabetic rats, a significant increase in the levels of glucose, glycated hemoglobin, hydroxyproline, collagen content, extent glycation, fluorescence, neutral salt, acid and pepsin soluble collagen content was absorbed with a significant decrease in the level of insulin, hemoglobin in streptozotocin-nicotinamide diabetic rats. Moreover, a daily administration of nonglucidic nutrient EMS and metformin significantly decreased the levels of glucose, glycated hemoglobin, hydroxyproline, collagen content, extent glycation, fluorescence, neutral salt, acid and pepsin soluble collagen content, whereas it increased insulin, hemoglobin levels in diabetic rats. The positive influence of nonglucidic nutrient on both collagen content and its properties suggests a potential mechanism for the ability of EMS to delay diabetic complications.     

The efficacy of a home-based nursing program in diabetic control of elderly people with diabetes mellitus living alone

The purpose of this study was to evaluate the efficacy of a home-based nursing program in the diabetic control of elderly people with diabetes mellitus living alone. Patients meeting the sampling criteria were recruited from a medical center and 10 health centers in Taipei for this quasi-experimental study. By matching the effects of age, sex, education, and history of diabetes, subjects were assigned semirandomly to two groups based on the intensity of home-based nursing care visitations. Group I was defined as daily visits to supervise diet, exercise, medication, and self-monitoring blood sugar (n = 15) and Group II as weekly visits to supervise diet, exercise, medication education, and self-monitoring blood sugar (n = 15). Patients who agreed only to receive blood examination were assigned to the control group (n = 14). The results of the study showed that reductions in fasting blood sugar, postmeal blood sugar, and hemoglobin A1c (HbA1c) in Groups I and II were significantly greater than those in the control group. The reduction in the total cholesterol and low-density lipoprotein in Groups I and II was significantly greater than that in the control group. There were no significant differences among the three groups in the improvement of high-density lipoprotein (HDL) and triglycerides (TGs). Group I revealed a significantly greater weight reduction compared to Group II. There was no significant difference between Groups I and II in the improvements of diabetes knowledge, depression level, or quality of life. From the research findings, based on cost-effectiveness, it is recommend that Program II be implemented.     

Pancreas β‐cells morphology,liver antioxidant enzymes and liver oxidative parameters in alloxan‐resistant and alloxan‐susceptible Wistar rats: a viable model system for the study of concepts into reactive oxygen species

The aim of this study was to investigate biochemical and antioxidant parameters in alloxan‐resistant (ALR) and alloxan‐susceptible (ALS) rats. Diabetes was induced in 60‐day‐old male Wistar rats by a single intraperitonial injection of alloxan (AL, 150 mg/kg). Ten days after induction, a group of rats showed a significant decrease in glycemia. This group was named alloxan‐resistant group. Susceptible rats showed a remarkable increase in the plasma lipid content, blood glucose and HbA1. Glycogen content in the liver decreased significantly in the ALS group (2.08 ± 0.41 mg%) compared with ALR group (4.22 ± 0.18). Aspartate aminotransferase and alanine aminotransferase activities were quantified in the plasma. Interestingly, ALR rats showed a decrease in both activities (42.1 ± 6.11 and 21.7 ± 5.54 U/mL) when compared with ALS rats (59.1 ± 6.55 and 58.1 ± 7.28 U/mL). The TBARS index was significantly increased in the ALS liver (0.38 ± 0.08 nm /mg protein) when compared with the ALR liver (0.18 ± 0.04). Superoxide dismutase and catalase activities in the ALR (230 ± 13 and 131 ± 15 U/mg protein) liver showed a marked increase when compared with the ALS liver (148 ± 13 and 68 ± 5 U/mg protein). The immunohistochemical and hematoxilin–eosin analysis also revealed that pancreatic islets of ALR rats display a different morphology amongst the groups. These results suggest an increased regenerative or recovery process in the ALR rat pancreatic islets and an increased hepatic antioxidant defenses in these group of alloxan‐resistant rats.     

Potentiation of carbon tetrachloride-induced hepatotoxicity in alloxan- or strepto- zotocin-diabetic rats.

Studies were performed to examine the effects of alloxan- or streptozotocin-induced diabetes on carbon tetrachloride (CCl4) liver injury. Male rats were pretreated with single i.v. injections of alloxan monohydrate (40 or 80 mg/kg) or streptozotocin (65 mg/kg). A challenging dose of CCl4 (0.1 ml/kg i.p.) was given to rats 4 days after alloxan pretreatment or 5 days after streptozotocin pretreatment, and the animals were sacrificed 24 hours later. Biochemical and morphologic evidence was obtained to show that pretreatment with the diabetogenic agents markedly enhanced CCl4-induced hepatotoxity. The challenging dose of CCl4 had no effect on the serum glutamic pyruvic transaminase (SGPT) activity in control rats. However, the administration of this dose of CCl4 to rats pretreated with 40 and 80 mg/kg of alloxan as well as to rats pretreated with streptozotocin resulted in 11-, 68-, and 32-fold increases, respectively, in SGPT activity. Hepatic triglyceride concentrations in the diabetic rats were also markedly elevated above control values after CCl4 challenge. Alloxan- or streptozotocin-pretreatment alone did not enhance these biochemical parameters of liver injury. Hepatic glucose-6-phosphatase activity, which increased in the rats given a diabetogenic agent, was lowered as a result of CCl4 injection. Insulin treatment of rats given alloxan (80 mg/kg) markedly protected against CCl4-induced hepatotoxicity. The severity of the morphologic changes in diabetic rats given CCl4 correlated with the biochemical findings.     

Determination of the non-enzymatic glycation of hemoglobin by isoelectrofocusing of its globin chains

Micro cation exchange chromatography determination of HbA1c does not provide a complete picture of Hb glycation, for it does not determine all the glycated forms of hemoglobin. For the determination of total glycation, we describe here a rod IEF method, which allows the simultaneous quantitation of glycation on alpha and beta globin chains. The method exhibits good sensitivity; it is not affected by artifacts deriving from temperature, hypertriglyceridemia, Hb variants or labile HbA1 (aldiminic Hb). The results obtained indicate that in a normal population approximately 18% of the beta chain and 8% of the alpha chain are glycated. These mean percentages increase in the diabetic to 28% and 12%, respectively. The beta chain is glycated on both valine and lysine residues, while the alpha chain is glycated only on the latter. HbA1 values from micro cation exchange chromatography are significantly related to both alpha and beta glycation. Thus, valinic or lysinic glycation have roughly the same clinical significance.     

Structural and glycation site changes of albumin in diabetic patient with very high glycated albumin

BACKGROUND: Glycated albumin (GA) has been utilized to monitor mid-term glycemic control, and reflects the status of blood glucose more rapidly and effectively than hemoglobin A(1c) (HbA(1c)). To examine the relationship between GA level and structural changes or glycation sites of albumin, we analyzed pre- and post-treatment samples from a diabetic patient with extraordinary increase of GA. METHOD: A female diabetic patient with poor glycemic control had a GA >94% and was treated with intensive insulin therapy to decrease blood glucose. We analyzed changes in fluorescence derived from tryptophan (Trp) and advanced glycation end product (AGE) of albumin isolated/purified from pre- and post-treatment samples. To determine the sites of glycation of albumin, samples were carboxymethylated and digested by Glu-C endoprotease, and peptides were analyzed using liquid chromatography/mass spectrometry. RESULTS: GA level decreased almost linearly and reflected the improved glycemic state well. Trp-related fluorescence of pre- and post-treated samples did not change while AGE-related fluorescence increased depending on GA level. Ten major glycation sites were detected in the pre-treatment sample, while 3 major glycation sites were detected in post-treated samples. CONCLUSIONS: GA level reflects the status of blood glucose more rapidly than HbA(1c). Since GA level was related to AGE-related fluorescence and number of glycation sites, it might be a good marker for not only glycemic control of diabetic patients but also structural and functional changes of albumin.     

糖化血红蛋白对于2型糖尿病检测的临床意义

目的了解糖化血红蛋白（HbA1C）与糖尿病及其并发症的关系,及时控制糖尿病及其并发症的发生和发展。方法对100例糖尿病及糖尿病伴有并发症患者及50例健康人的HbA1C、空腹血糖（FBG）进行测定,并作分析。结果健康对照组的HbA1C为（5.22±0.48）%,FBG为（4.22±0.91）mmol/L;糖尿病组的HbA1C为（9.58±2.08）%,FBG为（8.76±4.69）mmol/L;糖尿病伴并发症的HbA1C为（11.06±2.92）%,FBG为（11.78±4.82）mmol/L。结论 HbA1C的控制对预防糖尿病及其并发症的发生和发展极为重要。     

Lectin‐Based Estimation of Glycated Hemoglobin in Diabetes Mellitus

This study was undertaken to distinguish between normal and diabetic subjects by lectin–glycated hemoglobin interaction. The quantitative precipitin method was performed for the interaction between glucose‐specific lectin Concanavalin A (Con A) and the glucose‐containing RBC‐lysate for the estimation of calculated HbA1c% from a standard curve. The standard curve was prepared by plotting the optical density of the precipitin for the interaction of standard HbA1c concentration with Con A against HbA1c reference standard. The absorbance range of the precipitate was 0.14–0.20 in normal subjects and the corresponding calculated HbA1c% along with plasma glucose (mg/dl) levels was 4.1–5.8% and 82–101 mg/dl respectively. Higher absorbance values, 0.22–0.42, were obtained in diabetic patients when the calculated HbA1c% was 6.3–12.2% and plasma glucose level was 120–292 mg/dl. Almost similar results were observed for HbA1c% (6.1–11.9%) of the same diabetic samples measured by conventional ion‐exchange high performance liquid chromatography (HPLC). Excellent correlation coefficients of the two methods from regression analysis graph for normal (r = 0.98) and diabetic patients (r = 0.99) were observed. Furthermore, nondiabetic and diabetic hemoglobin variant subjects showed similar HbA1c% by our lectin‐based assay when compared with standard HPLC method. We conclude that this lectin‐based assay may be adopted to estimate glycated hemoglobin level in differentiating between normal and diabetic patients. This assay offers a good correlation with standard HPLC method. Moreover; the method is convenient, cheap, and needs no sophisticated instruments.     

Glucagon-like peptide 1 receptor agonist ZP10A increases insulin mRNA expression and prevents diabetic progression in db/db mice

We characterized the novel, rationally designed peptide glucagon-like peptide 1 (GLP-1) receptor agonist H-HGEGTFTSDLSKQMEEEAVRLFIEWLKNGGPSSGAPPSK KKKKK-NH2 (ZP10A). Receptor binding studies demonstrated that the affinity of ZP10A for the human GLP-1 receptor was 4-fold greater than the affinity of GLP-1 (7-36) amide. ZP10A demonstrated dose-dependent improvement of glucose tolerance with an ED50 value of 0.02 nmol/kg i.p. in an oral glucose tolerance test (OGTT) in diabetic db/db mice. After 42 days of treatment, ZP10A dose-dependently (0, 1, 10, or 100 nmol/kg b.i.d.; n = 10/group), decreased glycosylated hemoglobin (HbA1C) from 8.4 +/- 0.4% (vehicle) to a minimum of 6.2 +/- 0.3% (100 nmol/kg b.i.d.; p < 0.05 versus vehicle) in db/db mice. Fasting blood glucose (FBG), glucose tolerance after an OGTT, and HbA1C levels were significantly improved in mice treated with ZP10A for 90 days compared with vehicle-treated controls. Interestingly, these effects were preserved 40 days after drug cessation in db/db mice treated with ZP10A only during the first 50 days of the study. Real-time polymerase chain reaction measurements demonstrated that the antidiabetic effect of early therapy with ZP10A was associated with an increased pancreatic insulin mRNA expression relative to vehicle-treated mice. In conclusion, long-term treatment of diabetic db/db mice with ZP10A resulted in a dose-dependent improvement of FBG, glucose tolerance, and blood glucose control. Our data suggest that ZP10A preserves beta-cell function. ZP10A is considered one of the most promising new drug candidates for preventive and therapeutic intervention in type 2 diabetes.     

Effects of bis(alpha-furancarboxylato)oxovanadium(IV) on non-diabetic and streptozotocin-diabetic rats

BACKGROUND: Bis(alpha-furancarboxylato)oxovanadium(IV) (BFOV), a new orally active anti-diabetic vanadium complex with organic agent, has been synthesized and characterized. The current study examined the stability in aqueous solution and effects of the complex on carbohydrate and lipid metabolism in non-diabetic and streptozotocin-induced diabetic rats. METHODS: Diabetic rats were induced by a single dose injection of streptozotocin (STZ, 50 mg/kg body weight, i.p.). The rats were randomly divided into non-diabetic (control, CON), diabetic (DM) and BFOV (0.2 mmol/kg body weight)-treated, diabetic-BFOV (0.1, 0.2 and 0.4 mmol/kg body weight) groups. All substances were given intragastrically to non-diabetic and STZ-induced diabetic rats for 4 weeks. Blood glucose concentration was monitored during administration and, at the end of experiment glycosylated hemoglobin, serum insulin, lipid concentrations and glycogen content were observed. RESULTS: Administration of BFOV to STZ-diabetic rats dose-dependently reduced blood glucose concentration when compared to diabetic rats (P<0.01), but it did not influence blood glucose in non-diabetic rats. Serum insulin concentrations were not increased in the BFOV-treated diabetic groups and, in contrast, significantly lowered in the 0.2 mmol/kg body weight BFOV-treated non-diabetic group at the end of experiment. Moreover, BFOV markedly reduced glycosylated hemoglobin concentration and improved dyslipidemia in STZ-diabetic rats, in a dose-dependent manner (P<0.05, P<0.01), but had no significant effect on non-diabetic rats. CONCLUSION: The organic vanadium complex was found to effectively attenuate diabetic alterations in STZ-diabetic rats.     

Glycosylated hemoglobin monitoring of diabetic patients: a pilot study and case report

Fasting and post-prandial blood glucose values have been found to be not totally representative of daily mean blood glucose concentration. Glycosylated hemoglobin (HbA1c) can be used as a supplemental monitoring device in the management and control of the diabetic patient. A pilot study on HbA1c was performed on a severe insulin dependent diabetic who had fasting glucose levels of 200-400 mg/dl over a six month period. The experimental data indicates that for every 10 mg/dl increase in glucose level, there is a corresponding increase in HbA1c of about .35%. Rate of formation of HbA1c depends on blood glucose concentration and is a slow continuous non-enzymatic process occurring during the normal 120 life span of the red blood cell. As such, it can be a useful monitoring tool.