Reduction of Plasma Leptin Concentrations by Arginine but Not Lipid Infusion in Humans

Objective: We examined short-term effects of arginine infusion on plasma leptin in diabetic and healthy subjects. Research Methods and Procedures: Arginine stimulation tests were performed in C-peptide negative type 1 [DM1; hemoglobin A_1c; 7.3 ± 0.3%], hyperinsulinemic type 2 diabetic (DM2; 7.6 ± 0.7%), and nondiabetic subjects (CON; 5.4 ± 0.1%). Results: Fasting plasma leptin correlated linearly with body mass index among all groups (r = 0.61, p = 0.001). During arginine infusion, peak plasma insulin was lower in DM1 than in DM2 (p < 0.05) and CON (p < 0.01). Plasma leptin decreased within 30 minutes by ∼11% in DM1 (p < 0.001), DM2 (p < 0.01), and CON (p < 0.005), slowly returning to baseline thereafter. Plasma free fatty acids (FFAs) were higher in DM1 (0.6 ± 0.1 mM) and DM2 (0.6 ± 0.1 mM) than in CON (0.4 ± 0.1 mM, p < 0.05) and transiently declined by ∼50% (p < 0.05) at 45 minutes in all groups before rebounding toward baseline. To examine the direct effects of FFAs on plasma leptin, we infused healthy subjects with lipid/heparin and glycerol during fasting, and somatostatin-insulin (∼35 pM) -glucagon (∼90 ng/mL) clamps were performed. In both protocols, plasma leptin continuously declined by ∼25% (p < 0.05) during 540 minutes without any difference between the high and low FFA conditions. Discussion: Arginine infusion transiently decreased plasma leptin concentrations both in insulin-deficient and hyperinsulinemic diabetic patients, indicating a direct inhibitory effect of the amino acid but not of insulin or FFAs.     

Diagnostic utility of BNP,corin and furin as biomarkers for cardiovascular complications in type 2 diabetes mellitus patients

Abstract

Context: The number of patients with type 2 diabetes mellitus (T2DM) is progressively increasing, and diabetic cardiovascular complications have become a public health problem. Brain or B-type natriuretic peptide (BNP) is a cardiac hormone synthesized as a pre-pro-peptide. pro-BNP is produced by cleaving the signal peptide then two proprotein convertases, corin and furin cleave pro-BNP to form a biologically active hormone. Two corin single nucleotide polymorphisms (SNPs) have been reported to alter corin protein conformation and impair its biological activity.

Objective: We aimed to investigate the potential role of corin and furin in comparison to BNP as biomarkers for predicting cardiovascular complications in T2DM patients. The association of corin gene SNPs with corin levels was also examined.

Methods: Seventy-five subjects were recruited in this study, including 25 T2DM patients with complications, 25 T2DM patients without complications as well as 25 healthy subjects. Plasma BNP, corin and furin levels were measured using enzyme-linked immunosorbent assays. Two corin SNPs were genotyped using allele specific oligonucleotide-polymerase chain reaction.

Results: Both furin and BNP were found to be more sensitive than corin (80% versus 56%, p?=?0.008), whereas furin showed higher specificity when compared to BNP (96% versus 84%, p?=?0.041) and corin (96% versus 64%, p?<?0.0001) in predicting cardiovascular complications in T2DM patients. Corin SNPs are not associated with corin levels, neither in the entire study cohort nor in the subgroup of T2DM patients with cardiovascular complications (p?>?0.05).

Conclusions: Furin may be useful, either alone or in combination with other biomarkers, for cardiovascular risk stratification assessment in T2DM patients.     

Elevated circulating vaspin levels were decreased by rosiglitazone therapy in T2DM patients with poor glycemic control on metformin alone

Vaspin has been regarded as a novel adipokine with potential insulin sensitizing properties. The aim of the present study is to investigate the effects of rosiglitazone therapy on plasma vaspin in type 2 diabetes patients (T2DM) inadequately controlled on metformin alone. A total of 105 subjects, including 37 subjects with normal glucose tolerance (NGT), 37 subjects with impaired glucose regulating (IGR), and 31 T2DM patients with poor glycemic control on metformin alone were enrolled in this study. Fasting plasma vaspin levels were higher in T2DM patients with poor glycemic control than that in IGR and NGT groups (1.19 ± 0.74 vs. 0.46 ± 0.26 and 0.54 ± 0.28 μg/L, P < 0.05). There was no difference between IGR and NGT groups. In T2DM patients, fasting plasma vaspin concentrations were significantly decreased after rosiglizatone therapy for 12 weeks (1.19 ± 0.74 vs. 0.91 ± 0.54 μg/L, P < 0.05), accompanied with significant amelioration of insulin sensitivity and glucose control. Plasma vaspin levels were positively associated with the fasting insulin and the homeostasis model assessment of IR (HOMA-IR). In conclusion, plasma vaspin level is higher in T2DM patients with poor glycemic control. And rosiglitazone therapy decreased plasma vaspin levels through glucose and insulin sensitivity regulation.     

Ala45Thr variation in neuroD1 gene is associated with early-onset type 2 diabetes with or without diabetic pedigree in Chinese

Objective: Based on onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous type 2 diabetes mellitus (T2DM), we investigated the Ala45Thr variation in unrelated early-onset and late-onset T2DM with or without diabetic pedigree and unrelated non-diabetic control subjects in Chinese. Methods: 175 early-onset and 194 late-onset type 2 diabetic patients were further divided into two subgroups according to with or without diabetic pedigree respectively. This NeuroD1-Ala45Thr variation were screened by PCR-direct sequencing in above 369 type 2 diabetic patients and 87 unrelated non-diabetic control subjects. We then compared the distribution of the Ala45Thr variation among the groups, searching for the predictive trends. Results: Frequencies of the variant (AA + GA genotype) in early-onset T2DM are obviously elevated, especially among diabetic pedigree subjects when compared to non-diabetic controls (p= 0.003) and late-onset T2DM subjects (p = 0.014). However, no significant differences were observed between late-onset T2DM with or without diabetic pedigree and non-diabetic control subjects. Conclusions: Our results suggest that 1) the NeuroD1-Ala45Thr variation may itself have an important role in susceptibility to or be in disequilibrium with early-onset T2DM in Chinese; 2) the Ala45Thr may affect the onset pattern of T2DM, i.e., early-onset but not late-onset T2DM in Chinese; and 3) onset-age stratified analysis may be useful to determine the association of NeuroD1-Ala45Thr variation with susceptibility to genetic heterogeneous T2DM in Chinese.     

The APOE4 allele is associated with a decreased risk of retinopathy in type 2 diabetics

Background

Common polymorphisms within the apolipoprotein E (APOE) gene are suggested to be associated with the development of type 2 diabetes mellitus (T2DM), but the potential association with T2DM complications (nephropathy, neuropathy and retinopathy) remains unclear. We perform the case–control study to analyse the association between the APOE polymorphism and risk of T2DM and to analysed the potential relationship between the APOE and T2DM complications.

Methods and results

APOE variants (rs429358 and rs7412) were genotyped by TaqMan assay in T2DM patients (N?=?1274; N?=?829 with complications including retinopathy, neuropathy and nephropathy status) and with PCR–RFLP in healthy nondiabetic controls (N?=?2055). The comparison of subjects with genotypes associated with low plasma cholesterol (APOE2/E2 and APOE2/E3 carriers vs. others) did not show an association with T2DM (OR [95% CI]?=?0.88 [0.71–1.08). The differences remained insignificant after adjusting for diabetes duration, sex and BMI. Carriers of at least one APOE4 allele (rs429358) are protected against T2DM related retinopathy (OR [95% CI]?=?0.65 [0.42–0.99]. Protection against retinopathy is driven mostly by females (OR [95% CI]?=?0.50 [0.25–0.99]); and remains significant (P?=?0.044) after adjustment for diabetes duration and BMI.

Conclusion

Common APOE polymorphism was not associated with T2DM in the Czech population. Yet, APOE4 allele revealed an association with retinopathy. In particular, female T2DM patients with at least one APOE4 allele exhibit lower prevalence of retinopathy in our study subjects.

     

The PECAM-1 gene polymorphism — a genetic marker of myocardial infarction

We investigated a possible association between the C373G (Leu125Val) polymorphism in the platelet endothelial cell adhesion molecule-1 (PECAM-1) and myocardial infarction (MI) among patients with type 2 diabetes (T2DM) in the Slovene population (Caucasians). The study population of this cross-sectional analysis consisted of 452 subjects with T2DM lasting more than 10 years: 142 patients with MI (MI group) and 310 patients (control group) with no history of coronary diseases. There were significant differences of PECAM-1 genotype distribution in patients with MI (CC=28.2%, CG=47.2% and GG=24.6%) compared with subjects in the control group (CC=17.1%, CG=53.5% and GG=29.4%). The multivariate model showed that the CC genotype of the PECAM-1 gene polymorphism (C373G) (OR=1.9, 95% CI 1.2–3.0, P=0.007) was an independent risk factor for MI. The C allele frequency was also significantly higher (P=0.005) in MI (51.8%) than in control subjects (41%). In addition, our study revealed the connection between smoking habits, the duration of diabetes and the total and LDL cholesterol serum levels and MI in Slovene T2DM patients. We suggest that the tested polymorphism of PECAM-1 (C373G) is associated with MI. Therefore, it might be used as genetic marker of MI in T2DM.     

Vascular Dysfunction in Obstructive Sleep Apnea and Type 2 Diabetes Mellitus

Despite the high prevalence of obstructive sleep apnea (OSA) in type 2 diabetes mellitus (DM), the attributable vascular risk from each condition is unknown. We hypothesize that OSA may have a similar effect on vascular function as type 2 diabetes does. Healthy normal‐weight subjects, healthy obese subjects, subjects with type 2 diabetes, and obese subjects with OSA were enrolled. Vascular function was assessed with brachial artery ultrasound for flow‐mediated dilatation (FMD) and in skin microcirculation by laser Doppler flowmetry. One hundred fifty‐three subjects were studied: healthy normal‐weight controls (NCs) (n = 14), healthy obese controls (OCs) (n = 33), subjects with DM (n = 68), and obese subjects with OSA (n = 38). The DM group did not undergo sleep study and thus may have had subclinical OSA. The OSA and type 2 diabetes groups had impaired FMD as compared to both the normal‐weight and OC groups (5.8 ± 3.8%, 5.4 ± 1.6% vs. 9.1 ± 2.5%, 8.3 ± 5.1%, respectively, P < 0.001, post hoc Fischer test). When referenced to the NC group, a multiple linear regression model adjusting for covariates found that baseline brachial artery diameter (β = ?3.75, P < 0.001), OSA (β = ?2.45, P = 0.02) and type 2 diabetes status (β = ?2.31, P = 0.02), negatively predicted % FMD. OSA status did not seem to affect nitroglycerin‐induced vasodilation (endothelium‐independent) of the brachial artery or vascular function in the skin microcirculation. OSA impairs endothelial function in the brachial artery to a similar degree as type 2 diabetes does. OSA, however, does not appear to affect brachial endothelium‐independent vasodilation or skin microcirculatory function. Treatment of OSA in patients with concomitant type 2 diabetes, therefore, may be a potential therapeutic option to improve macro‐, but not microvascular outcomes.     

Characteristics of Diabetic and Nondiabetic Patients With Thyroid Eye Disease in the United States: A Claims-Based Analysis

ObjectiveThyroid eye disease (TED) is a debilitating autoimmune disease characterized by ocular and periorbital tissue inflammation, proptosis, and visual impairment. The known risk factors for TED include radioactive iodine therapy, female sex, and smoking. The risk factors for severe TED include hyperthyroidism, male sex, smoking, and diabetes; however, little is known about how diabetes mellitus (DM) influences TED. This claims-based analysis examined TED characteristics in patients with and without diabetes.MethodsSymphony database (2010-2015 U.S. claims) was mined for patients with ≥1 Graves’ disease diagnosis code and ≥1 TED-associated eye code, including proptosis, strabismus, diplopia, lid retraction, exposure keratoconjunctivitis, and optic neuropathy (ON). DM status was determined based on type 1 or type 2 diabetes coding. Sight-threatening TED was defined as ≥1 ON or exposure keratoconjunctivitis code.ResultsA total of 51 220 patients were identified. Of them, 2618 (5.1%) and 12 846 (25.1%) had type 1 and type 2 DM, respectively. Patients with and without DM had similar characteristics, but patients with DM were more often men (type 1: 30.3%, type 2: 28.7% vs no DM: 20.5%; both P < .001) and older at the first TED code. In patients with DM, strabismus (25.4%, 22.6% vs 19.9%) and diplopia (38.6%, 37.9% vs 29.9%) occurred more often but proptosis occurred less often (42.3%, 46.3% vs 58.5%; all P < .001). Sight-threatening TED occurred more often in patients with DM because of higher ON rates.ConclusionPatients with TED and DM may have more extraocular muscle involvement. Furthermore, the higher prevalence of severe TED stemmed from higher ON rates, possibly associated with diabetes-related vasculopathies. These hypothesis-generating data warrant further exploration.     

Circulating expression levels of CircHIPK3 and CDR1as circular-RNAs in type 2 diabetes patients

Background

Recent investigations suggested that deregulated levels of Circular RNAs (circRNAs) could be associated with type 2 diabetes mellitus (T2DM) pathogenesis. Accordingly, this study aimed to determine the expression levels of circulating CircHIPK3, CDR1as and their correlation with biochemical parameters in patients with T2DM, pre-diabetes and control subjects.

Methods and results

The expression of circRNAs in peripheral blood was determined using QRT-PCR in 70 patients with T2DM, 60 pre-diabetes and in 69 age and sex matched healthy controls. Moreover, bioinformatics tools were applied to explore and predict the potential interactions between circRNAs and other non-coding RNAs (ncRNAs). Our analysis revealed that the expression level of CircHIPK3 was significantly elevated in T2DM patients compared to healthy participants (P?<?0.001) and pre-diabetes subjects (P?=?0.018). In addition, ROC analysis suggested that at the cutoff value of 0.24 and the sensitivity and specificity of 50% and 88.4%, respectively, CircHIPK3 could distinguish between T2DM patients and control subjects. Furthermore, it was observed that the expression level of CDR1as is higher in pre-diabetic individuals than healthy individuals (P?=?0.004). Finally, Spearman correlation analysis showed that there was a significant correlation between CircHIPK3 and CDR1as expression levels and clinical and anthropometrical parameters such as BMI, systolic and diastolic blood pressure, HbA1c and fasting blood glucose (P?<?0.005).

Conclusions

The data of this study provided evidence that the expression levels of CircHIPK3, CDR1as increased in T2DM and pre-diabetes subjects, respectively.

     

Restoration of acute insulin response in T2DM subjects 1 month after biliopancreatic diversion

Objective: Biliopancreatic diversion (BPD) restores normal glucose tolerance in a few weeks in morbid obese subjects with type 2 diabetes, improving insulin sensitivity. However, there is less known about the effects of BPD on insulin secretion. We tested the early effects of BPD on insulin secretion in obese subjects with and without type 2 diabetes. Methods and Procedures: Twenty‐one consecutive morbid obese subjects, 9 with type 2 diabetes (T2DM) and 12 with normal fasting glucose (NFG) were evaluated, just before and 1 month after BPD, by measuring body weight (BW), glucose, adipocitokines, homeostasis model assessment of insulin resistance (HOMA‐IR), acute insulin response (AIR) to e.v. glucose and the insulinogenic index adjusted for insulin resistance ([ΔI5/ΔG5]/HOMA‐IR). Results: Preoperatively, those with T2DM differed from those with NFG in showing higher levels of fasting glucose, reduced AIR (57.9 ± 29.5 vs. 644.9 ± 143.1 pmol/l, P < 0.01) and reduced adjusted insulinogenic index (1.0 ± 0.5 vs. 17.6 ± 3.9 1/mmol², P < 0.001). One month following BPD, in both groups BW was reduced (by ～11%), but all subjects were still severely obese; HOMA‐IR and leptin decreased significanlty, while high‐molecular weight (HMW) adiponectin and adjusted insulinogenic index increased. In the T2DM group, fasting glucose returned to non‐diabetic values. AIR did not change in the NFG group, while in the T2DM group it showed a significant increase (from 58.0 ± 29.5 to 273.8 ± 47.2 pmol/l, P < 0.01). In the T2DM group, the AIR percentage variation from baseline was significantly related to changes in fasting glucose (r = 0.70, P = 0.02), suggesting an important relationship exists between impaired AIR and hyperglycaemia. Discussion: BPD is able to restore AIR in T2DM even just 1 month after surgery. AIR restoration is associated with normalization of fasting glucose concentrations.     

β‐Cell Function Improvement After Biliopancreatic Diversion in Subjects With Type 2 Diabetes and Morbid Obesity

In subjects with obesity and type 2 diabetes mellitus (T2DM), biliopancreatic diversion (BPD) improves glucose stimulated insulin secretion, whereas the effects on other secretion mechanisms are still unknown. Our objective was to evaluate the early effects of BPD on nonglucose‐stimulated insulin secretion. In 16 morbid obese subjects (9 with T2DM and 7 with normal fasting glucose (NFG)), we measured insulin secretion after glucose‐dependent arginine stimulation test and after intravenous glucose tolerance test (IVGTT) before and 1 month after BPD. After surgery the mean weight lost was 13% in both groups. The acute insulin response during IVGTT was improved in T2DM after BDP (from 55 ± 10 to 277 ± 91 pmol/l, P = 0.03). A reduction of insulin response to arginine was observed in NFG, whereas opposite was found in T2DM. In particular, acute insulin response to arginine at basal glucose concentrations (AIR_basal) was reduced but insulin response at 14 mmol/l of plasma glucose (AIR₁₄) was increased. Therefore, after BPD any statistical difference in AIR₁₄ between NFG and T2DM disappeared (1,032 ± 123 for NFG and 665 ± 236 pmol/l for T2DM, P = ns). The same was observed for Slope_AIR, a measure of glucose potentiation, reduced in T2DM before BPD but increased after surgery, when no statistically significant difference resulted compared with NFG (Slope_AIR after BPD: 78 ± 11 in NFG and 56 ± 18 pmol/l in T2DM, P = ns). In conclusion, in obese T2DM subjects 1 month after BPD we observed a great improvement of both glucose‐ and nonglucose‐stimulated insulin secretions. The mechanisms by which BDP improve insulin secretion are still unknown.     

Resting Metabolic Rate in Severely Obese Diabetic and Nondiabetic Subjects

Objectives : To compare the resting metabolic rate (RMR) between diabetic and nondiabetic obese subjects and to develop a predictive equation of RMR for these subjects. Research Methods and Procedures : Obese adults (1088; mean age = 44.9 ± 12.7 years) with BMI ≥ 35 kg/m² (mean BMI = 46.4 ± 8.4 kg/m²) were recruited. One hundred forty‐two subjects (61 men, 81 women) were diagnosed with type 2 diabetes (DM), giving the prevalence of DM in this clinic population as 13.7%. RMR was measured by indirect calorimetry, and several multivariate linear regression models were performed using age, gender, weight, height, BMI, fat mass, fat mass percentage, and fat‐free mass as independent variables. Results : The severely obese patients with DM had consistently higher RMR after adjustment for all other variables. The best predictive equation for the severely obese was RMR = 71.767 ? 2.337 × age + 257.293 × gender (women = 0 and men = 1) + 9.996 × weight (in kilograms) + 4.132 × height (in centimeters) + 145.959 × DM (nondiabetic = 0 and diabetic = 1). The age, weight, and height‐adjusted least square means of RMR between diabetic and nondiabetic groups were significantly different in both genders. Discussion : Severely obese patients with type 2 diabetes had higher RMR than those without diabetes. The RMR of severely obese subjects was best predicted by an equation using age, gender, weight, height, and DM as variables.     

Plasma Adiponectin Levels in High Risk African‐Americans with Normal Glucose Tolerance,Impaired Glucose Tolerance,and Type 2 Diabetes**

Objective: We studied plasma adiponectin, insulin sensitivity, and insulin secretion before and after oral glucose challenge in normal glucose tolerant, impaired glucose tolerant, and type 2 diabetic first degree relatives of African‐American patients with type 2 diabetes. Research Methods and Procedures: We studied 19 subjects with normal glucose tolerance (NGT), 8 with impaired glucose tolerance (IGT), and 14 with type 2 diabetes. Serum glucose, insulin, C‐peptide, and plasma adiponectin levels were measured before and 2 hours after oral glucose tolerance test. Homeostasis model assessment‐insulin resistance index (HOMA‐IR) and HOMA‐β cell function were calculated in each subject using HOMA. We empirically defined insulin sensitivity as HOMA‐IR < 2.68 and insulin resistance as HOMA‐IR > 2.68. Results: Subjects with IGT and type 2 diabetes were more insulin resistant (as assessed by HOMA‐IR) when compared with NGT subjects. Mean plasma fasting adiponectin levels were significantly lower in the type 2 diabetes group when compared with NGT and IGT groups. Plasma adiponectin levels were 2‐fold greater (11.09 ± 4.98 vs. 6.42 ± 3.3811 μg/mL) in insulin‐sensitive (HOMA‐IR, 1.74 ± 0.65) than in insulin‐resistant (HOMA‐IR, 5.12 ± 2.14) NGT subjects. Mean plasma adiponectin levels were significantly lower in the glucose tolerant, insulin‐resistant subjects than in the insulin sensitive NGT subjects and were comparable with those of the patients with newly diagnosed type 2 diabetes. We found significant inverse relationships of adiponectin with HOMA‐IR (r = ?0.502, p = 0.046) and with HOMA‐β cell function (r = ?0.498, p = 0.042) but not with the percentage body fat (r = ?0.368, p = 0.063), serum glucose, BMI, age, and glycosylated hemoglobin A1C (%A1C). Discussion: In summary, we found that plasma adiponectin levels were significantly lower in insulin‐resistant, non‐diabetic first degree relatives of African‐American patients with type 2 diabetes and in those with newly diagnosed type 2 diabetes. We conclude that a decreased plasma adiponectin and insulin resistance coexist in a genetically prone subset of first degree African‐American relatives before development of IGT and type 2 diabetes.     

Reduced high-density lipoprotein 2b in non-obese type 2 diabetic patients analysed by a microfluidic chip method in a case–control study

Background: Alterations in high-density lipoprotein (HDL) subfractions, especially in the HDL2b subfraction, have been reported in type 2 diabetes mellitus (T2DM). However, new methods for convenient and reliable quantitation of HDL2b are yet to be developed.

Methods: Thirty-eight patients with T2DM were enrolled and age-, sex- and body mass index (BMI)-matched controls were selected from the same population. A microfluidic chip method was employed to analyse serum HDL subfractions.

Results: The microfluidic chip method revealed a significant reduction in HDL2b and its ratio to total HDL in T2DM patients. There was a reverse correlation for total HDL and HDL2b, and its ratio with triglycerides, homeostasis model assessment-insulin sensitivity index (HOMA-IS) and insulin resistance index (HOMA-IR).

Conclusions: We have shown a reduction of HDL2b and its ratio to total HDL by a novel chip method in T2DM patients. The significant correlation between HDL2b and HOMA-IS and HOMA-IR may have further predictive value in clinical utility.     

Butyrylcholinesterase K variant and the APOE-ε4 allele work in synergy to increase the risk of coronary artery disease especially in diabetic patients

We have previously shown that butyrylcholinesterase-K (BCHE-K, G1615A/Ala539Thr) variant increases the risk of coronary artery disease (CAD). In addition, we have found that the presence of APOE-ε4 allele augments the risk of CAD in patients with type II diabetes mellitus (T2DM/CAD). Here we explored the concomitant presences of two alleles of the BCHE-K and APOE-ε4 in increasing the risk of CAD or diabetes in T2DM patients with or without CAD and CAD patients without T2DM. This case–control study comprised 631 subjects undergoing their first coronary angiography. They were matched and randomly assigned into four groups: type II diabetic patients with no sign of CAD (T2DM), type II diabetic patients with CAD/ND (T2DM/CAD), CAD patients with no sign of diabetes (CAD/ND), and healthy individuals (NCAD/ND). BCHE-K variant and APOE genotypes were detected by PCR-RFLP and serum lipid level was measured enzymatically. We found that BCHE-K and APOE-ε4 allele act synergistically to increase the risk of CAD in both T2DM, non-diabetic and total CAD (TCAD = T2DM/CAD + CAD/ND) individuals. The level of synergy 1.5 and 1.2 fold are higher in CAD patients (OR = 4.5; P = 0.011) with T2DM than the non-diabetic CAD patients (OR = 3.07; P = 0.024) and TCAD patients (OR = 3.74; P = 0.018), respectively. The CAD subjects with and without T2DM and TCAD patients carrying both APOE-ε4 allele and BCHE-K had significantly lower plasma HDL-C (P values = 0.008, 0.047, and 0.036, respectively) and higher plasma LDL-C (P values = 0.025, 0.048, and 0.04, respectively), than that of the control carriers both APOE-ε4 and BCHE-K. We have found that BCHE-K and APOE-ε4 allele not only act synergistically to increase the risk of CAD, particularly in T2DM subjects in population from western Iran, who have high levels of LDL-C and low levels of HDL-C, suggesting that a specific therapeutic intervention should be considered for these particular groups of patients.     

Retinol‐binding Protein 4 (RBP4) Protein Expression Is Increased in Omental Adipose Tissue of Severely Obese Patients

Visceral fat has been linked to insulin resistance and type 2 diabetes mellitus (T2DM); and emerging data links RBP4 gene expression in adipose tissue with insulin resistance. In this study, we examined RBP4 protein expression in omental adipose tissue obtained from 24 severely obese patients undergoing bariatric surgery, and 10 lean controls (4 males/6 females, BMI = 23.2 ± 1.5 kg/m²) undergoing elective abdominal surgeries. Twelve of the obese patients had T2DM (2 males/10 females, BMI: 44.7 ± 1.5 kg/m²) and 12 had normal glucose tolerance (NGT: 4 males/8 females, BMI: 47.6 ± 1.9 kg/m²). Adipose RBP4, glucose transport protein‐4 (GLUT4), and p85 protein expression were determined by western blot. Blood samples from the bariatric patients were analyzed for serum RBP4, total cholesterol, triglycerides, and glucose. Adipose RBP4 protein expression (NGT: 11.0 ± 0.6; T2DM: 11.8 ± 0.7; lean: 8.7 ± 0.8 arbitrary units) was significantly increased in both NGT (P = 0.03) and T2DM (P = 0.005), compared to lean controls. GLUT4 protein was decreased in both NGT (P = 0.02) and T2DM (P = 0.03), and p85 expression was increased in T2DM subjects, compared to NGT (P = 0.03) and lean controls (P = 0.003). Regression analysis showed a strong correlation between adipose RBP4 protein and BMI for all subjects, as well as between adipose RBP4 and fasting glucose levels in T2DM subjects (r = 0.76, P = 0.004). Further, in T2DM, serum RBP4 was correlated with p85 expression (r = 0.68, P = 0.01), and adipose RBP4 protein trended toward an association with p85 protein (r = 0.55, P = 0.06). These data suggest that RBP4 may regulate adiposity, and p85 expression in obese‐T2DM, thus providing a link to impaired insulin signaling and diabetes in severely obese patients.     

Comparison of 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels using mass spectrometer and urine albumin creatinine ratio as a predictor of development of diabetic nephropathy

Abstract

Background. Measurement of urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) has recently become more popular as a means of assessing oxidative stress in the human body. The aim of this study is to compare the levels of urine 8-OHdG in patients with type 2 diabetes with and without nephropathy and to evaluate its role as a biochemical marker for distinguishing these patients from healthy and patients without complications. Methods. For this purpose, 52 patients with type 2 diabetes mellitus (32 with nephropathy (DMN), 20 without nephropathy (DM)) and 20 healthy control subjects (C) were included in this study. The urine concentrations of 8-OHdG were measured by modified LC-MS/MS method and compared with the first morning voiding urine albumin/creatinine ratio (UACR) and HbA1c values of the same patients. Results. The concentrations of urine 8-OHdG in DMN and DM patients were higher than those of the control subjects (3.47?±?0.94, 2.92?±?1.73, 2.1?±?0.93 nmol/mol creatinine, respectively). But there was no statistical difference between DMN and DM (p =?0.115). There is significant correlation between urinary 8-OHdG and UACR (r =?0.501, p <?0.001). According to ROC analysis, the AUC value of HbA1c was higher than the value of the AUC of 8-OHdG (0.882 and 0.771, respectively). Conclusions. This study shows that the urine 8-OHdG levels increase in diabetic patients. However, urinary 8-OHdG is not a useful clinical marker, compared with UACR, to predict the development of diabetic nephropathy in diabetic patients.     

Pre-analytical and biological variability in circulating interleukin 6 in healthy subjects and patients with rheumatoid arthritis

Abstract

Interleukin (IL)-6, a key player in the inflammatory response, may be a useful biomarker in rheumatoid arthritis (RA). The aim was to determine analytical variability, a reference interval in healthy subjects, and long- and short-term variation in serum and plasma IL-6 in healthy subjects and RA patients. An enzyme-linked immunosorbent assay from R&;D was used for determination of serum and plasma IL-6. The IL-6 concentration did not depend on the type of anticoagulant used or the 3-h time delay between sampling and processing or repeated freeze–thaw cycles. The median plasma and serum IL-6 in 318 healthy subjects were 1.3 pg ml^?1 (range 0.33–26) and 1.4 pg ml^?1 (range 0.25–23), respectively. The median coefficient of variation in plasma IL-6 in 27 healthy subjects during 1 month, and repeated after 6 and 12 months were 27%, 31% and 26%, respectively. No significant long-term changes were observed in serum IL-6 over a 3-year period (14%, p=0.33). Exercise (cycling) increased serum IL-6 in healthy subjects but not in RA patients. In conclusion, circulating IL-6 is stable regarding sample handling and shows little variation over time. Changes in IL-6 concentrations >60% (2 times the biological variation) are likely to reflect changes in disease activity and not only pre-analytical or normal biological variability.     

Plasma angiogenesis and oxidative stress markers in patients with diabetic retinopathy

Abstract

Background: Neovascularization in the retina and hyperglycaemia-induced oxidative stress are implicated in the pathogenesis of diabetic retinopathy (DR). In this study, we hypothesized that the plasma angiogenic and oxidative stress markers associated with these derangements could aid in the screening of diabetic patients who are at an increased risk of developing retinopathy.

Methods: This study included normal (n?=?148), type2 diabetes without retinopathy (DNR; n?=?148), proliferative DR (PDR; n?=?74) and non-PDR (NPDR; n?=?148) subjects. Plasma concentrations of vascular endothelial growth factor-A (VEGF-A), hypoxia-inducible factor-1α (HIF-1α), matrix metalloproteinase-9 (MMP-9), pigment epithelium-derived factor (PEDF), nitric oxide (NO), soluble receptors for advanced glycation end products (sRAGE), malondialdehyde (MDA) and protein thiols were estimated.

Results: A statistically significant increase was observed in the plasma concentrations of pro-angiogenic factors and markers of oxidative stress in both retinopathy groups. By contrast, the concentrations of anti-angiogenic factors and antioxidants were decreased significantly in these groups. Receiver operating characteristic analysis indicated that the plasma thresholds of HIF-1α and PEDF can be suitable markers in case of NPDR. However, in PDR, HIF-1α, NO, MMP-9 and PEDF showed high sensitivity and specificity.

Conclusions: The factors associated with hypoxia, matrix degradation and angiogenic inhibition play a crucial role in predicting DR.     

Serum Levels of Soluble CD26/Dipeptidyl Peptidase-IV in Type 2 Diabetes Mellitus and Its Association with Metabolic Syndrome and Therapy with Antidiabetic Agents in Malaysian Subjects

BackgroundA soluble form of CD26/dipeptidyl peptidase-IV (sCD26/DPP-IV) induces DPP-IV enzymatic activity that degrades incretin. We investigated fasting serum levels of sCD26/DPP-IV and active glucagon-like peptide-1 (GLP-1) in Malaysian patients with type 2 diabetes mellitus (T2DM) with and without metabolic syndrome (MetS), as well as the associations between sCD26/DPP-IV levels, MetS, and antidiabetic therapy.MethodsWe assessed sCD26/DPP-IV levels, active GLP-1 levels, body mass index (BMI), glucose, insulin, A1c, glucose homeostasis indices, and lipid profiles in 549 Malaysian subjects (including 257 T2DM patients with MetS, 57 T2DM patients without MetS, 71 non-diabetics with MetS, and 164 control subjects without diabetes or metabolic syndrome).ResultsFasting serum levels of sCD26/DPP-IV were significantly higher in T2DM patients with and without MetS than in normal subjects. Likewise, sCD26/DPP-IV levels were significantly higher in patients with T2DM and MetS than in non-diabetic patients with MetS. However, active GLP-1 levels were significantly lower in T2DM patients both with and without MetS than in normal subjects. In T2DM subjects, sCD26/DPP-IV levels were associated with significantly higher A1c levels, but were significantly lower in patients using monotherapy with metformin. In addition, no significant differences in sCD26/DPP-IV levels were found between diabetic subjects with and without MetS. Furthermore, sCD26/DPP-IV levels were negatively correlated with active GLP-1 levels in T2DM patients both with and without MetS. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-cholesterol (LDL-c) levels.ConclusionSerum sCD26/DPP-IV levels increased in T2DM subjects with and without MetS. Active GLP-1 levels decreased in T2DM patients both with and without MetS. In addition, sCD26/DPP-IV levels were associated with Alc levels and negatively correlated with active GLP-1 levels. Moreover, metformin monotherapy was associated with reduced sCD26/DPP-IV levels. In normal subjects, sCD26/DPP-IV levels were associated with increased BMI, cholesterol, and LDL-c.