Increased Platelet Reactivity and Proinflammatory Profile Are Associated with Intima-Media Thickness and Arterial Stiffness in Prediabetes.

Alterations of glucose homeostasis are associated with subclinical vascular damage; however, the role of platelet reactivity in this process has not been fully investigated. In this cross-sectional study, we evaluated the correlation between markers of platelet reactivity and inflammation and markers of vascular disease in subjects with prediabetes. Markers of platelet reactivity such as 11-dehydro-thromboxane B2 urinary levels (11-dh-TXB2) and mean platelet volume (MPV) and inflammatory indexes such as platelet-to-lymphocyte ratio (PLR) were evaluated in subjects with prediabetes (n = 48), new-onset type 2 diabetes (NODM, n = 60) and controls (n = 62). Furthermore, we assessed the cardiovascular risk profile of the study population with arterial stiffness and quality intima-media thickness (qIMT). Subjects with prediabetes and NODM exhibited higher 11-dh-TXB2 urinary levels and MPV and a proinflammatory profile with an increased PLR, high-sensitivity C-reactive protein, ferritin and fibrinogen. Furthermore, after multiple regression analyses, we found that urinary 11-dh-TXB2 was one of the major determinants of IMT and arterial stiffness parameters. In conclusion, subjects with prediabetes exhibit increased platelet reactivity as well as a proinflammatory profile. Furthermore, this condition is associated with early markers of cardiovascular disease.

High glomerular filtration rate is associated with impaired arterial stiffness and subendocardial viability ratio in prediabetic subjects.

BACKGROUND AND AIMS: High glomerular filtration rate (HGFR) is associated with cardiovascular damage in the setting of various conditions such as obesity and diabetes. Prediabetes was also associated with increased GFR, however, the association between prediabetes, HGFR and cardiovascular damage has not been investigated. In this study, we investigated the association between HGFR and early markers of cardiovascular disease in subjects with prediabetes. METHODS AND RESULTS: Augmentation pressure (Aug), augmentation index (AIx), subendocardial viability ratio (SEVR), pulse wave velocity (PWV), intima-media thickness (IMT) and estimated GFR (eGFR) were evaluated in 230 subjects with prediabetes. The eGFR was assessed using the Chronic Kidney Disease Epidemiology Collaboration formula. HGFR was defined as an eGFR above the 75th percentile. Prediabetic subjects were divided into two groups according to presence/absence of HGFR: 61 subjects with HGFR and 169 subjects without HGFR. Subjects with HGFR showed higher Aug, AIx and lower SEVR compared with prediabetic subjects with lower eGFR (14.1 ± 7.2 vs 10.8 ± 6.2, 32.9 ± 12.7 vs 27.6 ± 11.7, 153.5 ± 27.8 vs 162 ± 30.2, p < 0.05). No differences were found in PWV and IMT values between the two groups. Then, we performed multiple regression analysis to test the relationship between Aug, SEVR and several cardiovascular risk factors. In multiple regression analysis Aug was associated with age, systolic blood pressure (BP), HOMA-IR and eGFR; the major determinants of SEVR were systolic BP, HOMA-IR and eGFR. CONCLUSION: Subjects with prediabetes and HGFR exhibited an increased Aug, AIx and a reduced SEVR. These alterations are associated with eGFR, insulin resistance and systolic BP.

Analysis of steatosis biomarkers and inflammatory profile after adding on PCSK9 inhibitor treatment in familial hypercholesterolemia subjects with nonalcoholic fatty liver disease: A single lipid center real-world experience.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) may be crucial in subjects with familial hypercholesterolemia (FH). We aimed to evaluate the effect of the inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9-i) on steatosis biomarkers such as triglyceride-glucose index (TyG) and hepatic steatosis index (HSI) and analyse the role of TG/HDL in this population before and after adding-on PCSK9-i. METHODS AND RESULTS: In this observational study, we evaluated 26 genetically confirmed FH patients with NAFLD and an LDL-C off-target despite high-intensity statins plus ezetimibe. All patients added PCSK9-i treatment and obtained biochemical analysis and TyG and HSI evaluation at baseline and after six months of PCSK9-i. No difference of steatosis biomarkers was found after adding-on PCSK9-i therapy. In a secondary analysis, we divided the study population in two groups according to TG/HDL median value: high TG/HDL group (H-TG/HDL) and low TG/HDL group (L-TG/HDL). TyG and HSI were significantly lower in the L-TG/HDL than H-TG/HDL group (for TyG 9.05 ± 0.34 vs 9.51 ± 0.32; for HSI 38.43 ± 1.35 vs 41.35 ± 1.83, p value for both < 0.05). After six months of PCSK9-i therapy, TyG and HSI were significantly reduced in the L-TG/HDL group after PCSK9-i therapy (-7.5% and -8.4% respectively, p value for both < 0.05) and these biomarkers were lower compared to H-TG/HDL group (for TyG 8.37 ± 0.14 vs 9.19 ± 0.12; for HSI 35.19 ± 1.32 vs 39.48 ± 1.33, p value for both < 0.05). CONCLUSION: In conclusion, PCSK9-i therapy significantly ameliorate steatosis biomarkers in FH patients with low TG/HDL; our results appear to be consistent with a beneficial role of PCSK9-i on steatosis biomarkers in FH subjects with NAFLD.

Impaired glucagon suppression and reduced insulin sensitivity in subjects with prediabetes undergoing atorvastatin therapy.

OBJECTIVE: Statin therapy has been linked to an increased risk of type 2 diabetes in high-risk populations; however, the pathophysiology of this association remains to be clarified. We investigated glucagon suppression and its relationship with insulin resistance in prediabetic subjects undergoing atorvastatin therapy; in addition, we studied molecular insulin signaling in pancreatic α-cells exposed to atorvastatin in vitro. DESIGN AND METHODS: Fifty subjects with prediabetes were divided into two groups based on atorvastatin therapy. All subjects underwent an oral glucose tolerance test. Early (0-30 min), late (30-120 min) and overall (0-120 min) glucagon suppression were evaluated. Insulin sensitivity was estimated by the insulin sensitivity index (ISI0-120). Insulin signaling pathway and insulin-mediated glucagon suppression were investigated in pancreatic αTC1-6 cells chronically exposed (24 or 48 h) to atorvastatin (100 ng/mL). RESULTS: Individuals on statin therapy (n = 26) showed a significantly reduced early (0-30 min) (P = 0.003) and overall (0-120 min) (P = 0.01) glucagon suppression compared with controls (n = 24). In multivariate regression analysis, early glucagon suppression (0-30 min) exhibited a significant correlation with statin therapy. Regression analysis showed a significant association between ISI 0-120 and early0-30 (r = 0.33, P < 0.05) and overall0-120 (r = 0.38, P < 0.05) glucagon suppression. Moreover, in αTC1-6 cells atorvastatin treatment affected insulin-mediated glucagon suppression, insulin receptor phosphorylation and IRS-1-AKT pathway signaling. CONCLUSIONS: Prediabetic patients undergoing statin therapy exhibit impaired glucagon suppression associated with lower insulin sensitivity. Our data revealed a new molecular aspect behind the deregulation of insulin sensitivity secondary to statin exposure.

1 h Postload Glycemia Is Associated with Low Endogenous Secretory Receptor for Advanced Glycation End Product Levels and Early Markers of Cardiovascular Disease.

We investigated the correlation of the soluble receptor for advanced glycation end products (sRAGE) and endogenous secretory RAGE (esRAGE) with markers of cardiovascular disease in subjects with normal glucose tolerance (NGT) and 1 h postload glucose ≥155 mg/dL after an oral glucose tolerance test. We stratified 282 subjects without a previous diagnosis of diabetes into three groups: 123 controls (NGT and 1 h postload glycemia <155 mg/dL), 84 NGT and 1 h postload glycemia ≥155 mg/dL (NGT 1 h high), and 75 subjects with impaired fasting glucose and/or impaired glucose tolerance (IFG/IGT). NGT 1 h high subjects exhibited lower esRAGE (0.36 ± 0.18 vs. 0.4 5 ± 0.2, p < 0.05) and higher S100A12 levels than controls (5684 (3193.2-8295.6) vs. 3960.1 (2101.8-7419), p < 0.05). Furthermore, they showed an increased pulse wave velocity (PWV) and intima-media thickness (IMT). No differences were found between the NGT 1 h high group and the IFG/IGT group regarding cardiometabolic profiles. After multiple regression analyses, esRAGE was associated with glycated hemoglobin (HbA1c) and high-sensitivity C-reactive protein (hs-CRP). Age, HbA1c, and esRAGE were the determinants of IMT, whereas S100A12 and systolic pressure were the determinants of PWV. The NGT 1 h high group exhibited low esRAGE levels and an altered cardiometabolic profile. HbA1c, S100A12, and hs-CRP were associated with these alterations. In conclusion, subjects with NGT are not a homogeneous population, and they present different cardiovascular and glycometabolic risks.

Serum coding and non-coding RNAs as biomarkers of NAFLD and fibrosis severity.

BACKGROUND & AIMS: In patients with non-alcoholic fatty liver disease (NAFLD), liver biopsy is the gold standard to detect non-alcoholic steatohepatitis (NASH) and stage liver fibrosis. We aimed to identify differentially expressed mRNAs and non-coding RNAs in serum samples of biopsy-diagnosed mild and severe NAFLD patients with respect to controls and to each other. METHODS: We first performed a whole transcriptome analysis through microarray (n = 12: four Control: CTRL; four mild NAFLD: NAS ≤ 4 F0; four severe NAFLD NAS ≥ 5 F3), followed by validation of selected transcripts through real-time PCRs in an independent internal cohort of 88 subjects (63 NAFLD, 25 CTRL) and in an external cohort of 50 NAFLD patients. A similar analysis was also performed on liver biopsies and HepG2 cells exposed to oleate:palmitate or only palmitate (cellular model of NAFL/NASH) at intracellular/extracellular levels. Transcript correlation with histological/clinical data was also analysed. RESULTS: We identified several differentially expressed coding/non-coding RNAs in each group of the study cohort. We validated the up-regulation of UBE2V1, BNIP3L mRNAs, RP11-128N14.5 lncRNA, TGFB2/TGFB2-OT1 coding/lncRNA in patients with NAS ≥ 5 (vs NAS ≤ 4) and the up-regulation of HBA2 mRNA, TGFB2/TGFB2-OT1 coding/lncRNA in patients with Fibrosis stages = 3-4 (vs F = 0-2). In in vitro models: UBE2V1, RP11-128N14.5 and TGFB2/TGFB2-OT1 had an increasing expression trend ranging from CTRL to oleate:palmitate or only palmitate-treated cells both at intracellular and extracellular level, while BNIP3L was up-regulated only at extracellular level. UBE2V1, RP11-128N14.5, TGFB2/TGFB2-OT1 and HBA2 up-regulation was also observed at histological level. UBE2V1, RP11-128N14.5, BNIP3L and TGFB2/TGFB2-OT1 correlated with histological/biochemical data. Combinations of TGFB2/TGFB2-OT1 + Fibrosis Index based on the four factors (FIB-4) showed an Area Under the Curve (AUC) of 0.891 (P = 3.00E-06) or TGFB2/TGFB2-OT1 + Fibroscan (AUC = 0.892, P = 2.00E-06) improved the detection of F = 3-4 with respect to F = 0-2 fibrosis stages. CONCLUSIONS: We identified specific serum coding/non-coding RNA profiles in severe and mild NAFLD patients that possibly mirror the molecular mechanisms underlying NAFLD progression towards NASH/fibrosis. TGFB2/TGFB2-OT1 detection improves FIB-4/Fibroscan diagnostic performance for advanced fibrosis discrimination.

Pathophysiological, Molecular and Therapeutic Issues of Nonalcoholic Fatty Liver Disease: An Overview.

Nonalcoholic Fatty Liver Disease (NAFLD) represents the leading cause of liver disease in developed countries but its diffusion is currently also emerging in Asian countries, in South America and in other developing countries. It is progressively becoming one of the main diseases responsible for hepatic insufficiency, hepatocarcinoma and the need for orthotopic liver transplantation. NAFLD is linked with metabolic syndrome in a close and bidirectional relationship. To date, NAFLD is a diagnosis of exclusion, and liver biopsy is the gold standard for diagnosis. NAFLD pathogenesis is complex and multifactorial, mainly involving genetic, metabolic and environmental factors. New concepts are constantly arising in the literature promising new diagnostic and therapeutic tools. One of the challenges will be to better characterize not only NAFLD development but overall NAFLD progression, in order to better identify NAFLD patients at higher risk of metabolic, cardiovascular and neoplastic complications. This review analyses NAFLD epidemiology and the different prevalence of the disease in distinct groups, particularly according to sex, age, body mass index, type 2 diabetes and dyslipidemia. Furthermore, the work expands on the pathophysiology of NAFLD, examining multiple-hit pathogenesis and the role of different factors in hepatic steatosis development and progression: genetics, metabolic factors and insulin resistance, diet, adipose tissue, gut microbiota, iron deposits, bile acids and circadian clock. In conclusion, the current available therapies for NAFLD will be discussed.

Analysis of S100A12 plasma levels in hyperlipidemic subjects with or without familial hypercholesterolemia.

AIMS: Inflammation is a key regulatory process that links hypercholesterolemia and immune mechanisms promoting atherosclerosis. Inflammatory biomarkers may be helpful to better define the atherosclerotic burden in patients with high cholesterol levels such as familial hypercholesterolemia (FH). Our aim was to evaluate the concentration of S100A12 protein in FH patients and its association with pulse wave velocity (PWV). METHODS: We measured glucose and lipid profile, S100A12, sRAGE, esRAGE and PWV in 39 patients with a genetically confirmed diagnosis of FH and 39 hypercholesterolemic subjects without a clinical diagnosis of FH (Dutch score ≤ 3). All subjects were on statin treatment at the time of the enrollment. RESULTS: No difference of glucose and lipid profile was found in the two groups. FH patients had higher S100A12 plasma levels than non-FH subjects (12.87 ± 4.82 vs. 8.57 ± 4.87 ng/mL, p < 0.01). No difference of hs-CRP, sRAGE and esRAGE was found between the two groups. Also, PWV was higher in FH patients than non-FH subjects (8.63 ± 0.92 vs. 6.68 ± 0.73 m/s, p < 0.05). Finally, S100A12 was independently correlated with age (p < 0.01), genetic mutation (p < 0.01) and PWV (p < 0.001). CONCLUSIONS: FH patients exhibited higher S100A12 levels than non-FH subjects. A novel vascular inflammation pathway, other than hs-CRP, might be useful to better characterize cardiovascular risk profile.

Analysis of HDL-microRNA panel in heterozygous familial hypercholesterolemia subjects with LDL receptor null or defective mutation.

In the last years increasing attention has been given to the connection between genotype/phenotype and cardiovascular events in subjects with familial hypercholesterolemia (FH). MicroRNAs (miRs) bound to high-density lipoprotein (HDL) may contribute to better discriminate the cardiovascular risk of FH subjects. Our aim was to evaluate the HDL-miR panel in heterozygous FH (HeFH) patients with an LDLR null or defective mutation and its association with pulse wave velocity (PWV). We evaluated lipid panel, HDL-miR panel and PWV in 32 LDLR null mutation (LDLR-null group) and 35 LDLR defective variant (LDLR-defective group) HeFH patients. HDL-miR-486 and HDL-miR-92a levels were more expressed in the LDLR-null group than the LDLR-defective group. When we further stratified the study population into three groups according to both the LDLR genotype and history of ASCVD (LDLR-null/not-ASCVD, LDLR-defective/not-ASCVD and LDLR/ASCVD groups), both the LDLR/ASCVD and the LDLR-null/not-ASCVD groups had a higher expression of HDL-miR-486 and HDL-miR-92a than the LDLR-defective/not-ASCVD group. Finally, HDL-miR-486 and HDL-miR-92a were independently associated with PWV. In conclusion, the LDLR-null group exhibited HDL-miR-486 and HDL-miR-92a levels more expressed than the LDLR-defective group. Further studies are needed to evaluate these HDL-miRs as predictive biomarkers of cardiovascular events in FH.

Chronic Exposure to Palmitate Impairs Insulin Signaling in an Intestinal L-cell Line: A Possible Shift from GLP-1 to Glucagon Production.

Obesity and type 2 diabetes mellitus (T2DM) are characterized by insulin resistance and impaired glucagon-like peptide-1 (GLP-1) secretion/function. Lipotoxicity, a chronic elevation of free fatty acids in the blood, could affect insulin-signaling in many peripheral tissues. To date, the effects of lipotoxicity on the insulin receptor and insulin resistance in the intestinal L-cells need to be elucidated. Moreover, recent observations indicate that L-cells may be able to process not only GLP-1 but also glucagon from proglucagon. The aim of this study was to investigate the effects of chronic palmitate exposure on insulin pathways, GLP-1 secretion and glucagon synthesis in the GLUTag L-cell line. Cells were cultured in the presence/absence of palmitate (0.5 mM) for 24 h to mimic lipotoxicity. Palmitate treatment affected insulin-stimulated GLP-1 secretion, insulin receptor phosphorylation and IRS-1-AKT pathway signaling. In our model lipotoxicity induced extracellular signal-regulated kinase (ERK 44/42) activation both in insulin stimulated and basal conditions and also up-regulated paired box 6 (PAX6) and proglucagon expression (Gcg). Interestingly, palmitate treatment caused an increased glucagon secretion through the up-regulation of prohormone convertase 2. These results indicate that a state of insulin resistance could be responsible for secretory alterations in L-cells through the impairment of insulin-signaling pathways. Our data support the hypothesis that lipotoxicity might contribute to L-cell deregulation.

New treatment options for lipid-lowering therapy in subjects with type 2 diabetes.

Dyslipidemias represent a variety of quantitative and/or qualitative lipoprotein abnormalities. According to etiology, we distinguish primary dyslipidemias with strictly genetic background and secondary ones with their origin in other disease or pathological states. Diabetic dyslipidemia is a type of secondary dyslipidemia and plays an important role in determining the cardiovascular risk of subjects with type 2 diabetes. In these patients, insulin resistance is responsible for overproduction and secretion of atherogenic very low density lipoprotein. In addition, insulin resistance promotes the production of small dense low-density lipoprotein (LDL) and reduces high-density lipoprotein (HDL) production. Cardiovascular disease remains a leading cause of morbidity and mortality in diabetic patients. Previous results support the role for small, dense LDL particles in the etiology of atherosclerosis and their association with coronary artery disease. Moreover, lowering LDL cholesterol reduces the risk of cardiovascular death. Therefore, the European guidelines for the management of dyslipidemias recommend an LDL cholesterol goal < 100 mg/dL in diabetic subjects without cardiovascular events. Moreover, if triglycerides (TG) are elevated (> 400 mg/dL), they recommend a non-HDL cholesterol goal < 130 mg/dL in diabetic individuals without cardiovascular events. Statins are the first line of LDL-lowering therapy in diabetic patients and combined therapy with ezetimibe and statins could be useful in very high cardiovascular risk diabetic subjects. Furthermore, the effect of a fibrate as an add-on treatment to a statin could improve the lipid profile in diabetic individuals with high TG and low HDL cholesterol. Regarding new therapies, recent data from phase III trials show that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors considerably decrease LDL cholesterol. Thus, they may be useful in diabetic patients with concomitant diseases such as familial dyslipidemia, recurrent cardiovascular events, and elevated LDL cholesterol after second drug administration in addition to maximal statin dose or statin intolerance.

HbA1c Identifies Subjects With Prediabetes and Subclinical Left Ventricular Diastolic Dysfunction.

Context: Prediabetes is associated with subclinical cardiac changes associated with heart failure development. Objective: We investigated diastolic function and its association with markers of glycation and inflammation related to cardiovascular disease in patients with prediabetes. We focused on individuals with prediabetes identified only by glycated hemoglobin A1c [HbA1c; 5.7% to 6.4% and normal fasting glucose (NFG) and normal glucose tolerance (NGT) after an oral glucose tolerance test (OGTT)]. Design: Cross-sectional study. Setting: Departments of Clinical and Experimental Medicine and Cardiology, University of Catania, Catania, Italy. Main Outcome Measures: HbA1c, OGTT, Doppler echocardiography, soluble receptor for advanced glycation end products (sRAGEs), and endogenous secretory RAGE (esRAGE) were evaluated. Patients: We recruited 167 subjects with NFG/NGT who were stratified according to HbA1c level: controls (HbA1c <5.7%) and HbA1c prediabetes (HbA1c 5.7% to 6.4%). Results: Patients with HbA1c prediabetes (n = 106) showed a lower peak mitral inflow in early diastole (E wave) to late diastolic atrial filling velocity (A wave) ratio (E/A ratio) than controls (n = 61) (1.10 ± 0.24 vs 1.18 ± 0.23; P < 0.05). They showed a higher left atrium volume (LAV) (28.4 ± 5 vs 22.1 ± 3; P < 0.05) and sphericity index (SI) (0.6 ± 0.06 vs 0.5 ± 0.05; P < 0.05). After multiple regression analyses, HbA1c, sRAGE, and esRAGE were the major determinants of E/A ratio, LAV, and SI. Conclusions: Subjects with HbA1c prediabetes exhibited subclinical cardiac alterations associated with sRAGE, esRAGE, and HbA1c. These subjects would not have been classified as having prediabetes on the basis of fasting glycemia or post-OGTT values.

Atorvastatin but Not Pravastatin Impairs Mitochondrial Function in Human Pancreatic Islets and Rat ß-Cells. Direct Effect of Oxidative Stress.

Statins are a class of drugs widely prescribed as frontline therapy for lowering plasma LDL-cholesterol in cardiovascular risk prevention. Several clinical reports have recently suggested an increased risk of type 2 diabetes associated with chronic use of these drugs. The pathophysiology of this effect remains to be fully elucidated but impaired ß-cell function constitutes a potential mechanism. The aim of this study was to explore the effect of a chronic treatment with lipophilic and hydrophilic statins on ß-cell function, using human pancreatic islets and rat insulin-secreting INS-1 cells; we particularly focused on the role of mitochondria and oxidative stress. The present study demonstrates, for the first time, that atorvastatin (lipophilic) but not pravastatin (hydrophilic) affected insulin release and mitochondrial metabolism due to the suppression of antioxidant defense system and induction of ROS production in pancreatic ß-cell models. Mevalonate addition and treatment with a specific antioxidant (N-AcetylCysteine) effectively reversed the observed defects. These data demonstrate that mitochondrial oxidative stress is a key element in the pathogenesis of statin-related diabetes and may have clinical relevance to design strategies for prevention or reduction of statin induced ß-cell dysfunction and diabetes in patients treated with lipophilic statins.

Update on pre-diabetes: Focus on diagnostic criteria and cardiovascular risk.

Pre-diabetes, which is typically defined as blood glucose concentrations higher than normal but lower than the diabetes threshold, is a high-risk state for diabetes and cardiovascular disease development. As such, it represents three groups of individuals: Those with impaired fasting glucose (IFG), those with impaired glucose tolerance (IGT) and those with a glycated haemoglobin (HbA1c) between 39-46 mmol/mol. Several clinical trials have shown the important role of IFG, IGT and HbA1c-pre-diabetes as predictive tools for the risk of developing type 2 diabetes. Moreover, with regard to cardiovascular disease, pre-diabetes is associated with more advanced vascular damage compared with normoglycaemia, independently of confounding factors. In view of these observations, diagnosis of pre-diabetes is mandatory to prevent or delay the development of the disease and its complications; however, a number of previous studies reported that the concordance between pre-diabetes diagnoses made by IFG, IGT or HbA1c is scarce and there are conflicting data as to which of these methods best predicts cardiovascular disease. This review highlights recent studies and current controversies in the field. In consideration of the expected increased use of HbA1c as a screening tool to identify individuals with alteration of glycaemic homeostasis, we focused on the evidence regarding the ability of HbA1c as a diagnostic tool for pre-diabetes and as a useful marker in identifying patients who have an increased risk for cardiovascular disease. Finally, we reviewed the current evidence regarding non-traditional glycaemic biomarkers and their use as alternatives to or additions to traditional ones.

Low advanced glycation end product diet improves the lipid and inflammatory profiles of prediabetic subjects.

BACKGROUND: Prediabetes is associated with risk for cardiovascular disease, and the first step in its management emphasizes lifestyle and diet modifications; however, modern diets are high in advanced glycation end products (dAGEs), derived from processing methods that exert a pivotal role in promoting atherosclerotic risk. OBJECTIVE: We studied the effect of low vs standard dAGE diets (L-dAGEs vs S-dAGEs) on lipid profile, inflammation, and cardiovascular risk in prediabetic subjects. METHODS: A 24-week randomized dietary intervention was conducted on 62 prediabetic subjects. We evaluated lipid profile, endogenous secretory receptors for AGEs, high-sensitivity C-reactive protein, arterial stiffness, and intima-media thickness. RESULTS: After 24 weeks, patients with L-dAGEs showed a significant reduction of total cholesterol, apolipoprotein B, and low-density lipoprotein compared with controls (5.26 ± 1.09 vs 5.53 ± 0.87 mmol/L, P < .05; 0.77 ± 0.25 vs 1.16 ± 0.13 mmol/L, P < .05; and 3.53 ± 0.93 vs 3.68 ± 0.7 mmol/L, P < .05); with respect to baseline, high-sensitivity C-reactive protein levels were significantly reduced in the L-dAGEs group (0.21 [0.11-0.69] vs 0.12 [0.08-0.48] mg/dL, P < .05) but not in the S-dAGEs group. Endogenous secretory receptor for AGEs was similar in both the groups at baseline and at the 24-week follow-up. With respect to baseline, L-dAGE patients showed a significative reduction of intima-media thickness (0.77 [0.73-0.81] vs 0.73 [0.70-0.75] mm, P < .05). We did not observe the same reduction in S-dAGEs. No difference in arterial stiffness was found from baseline to follow-up in both the groups. CONCLUSIONS: L-dAGEs improved the lipid and inflammatory profiles of prediabetic subjects and seemed to reduce atherosclerotic burden compared with a standard diet. Further studies are needed to recommend this dietary regimen for prevention of cardiovascular risk in prediabetes.

Low Endogenous Secretory Receptor for Advanced Glycation End-Products Levels Are Associated With Inflammation and Carotid Atherosclerosis in Prediabetes.

CONTEXT: Prediabetes is associated with atherosclerotic vascular damage. OBJECTIVE: We investigated the correlation of endogenous secretory receptor for advanced glycation end-products (esRAGE), total soluble RAGE (sRAGE) and markers of inflammation, with early cardiovascular disease in subjects with prediabetes. We particularly focused on individuals with prediabetes identified only by glycated hemoglobin A1c (HbA1c) (5.7­6.4%) who had normal fasting glucose and were normotolerant after oral glucose tolerance test. DESIGN: This was a cross-sectional study. SETTING: The study was conducted in the Department of Clinical and Molecular Medicine, University of Catania, Italy. MAIN OUTCOME MEASURE: sRAGE, esRAGE, carboxymethyl-lysine, S100A12, HbA1c, fasting glycemia, oral glucose tolerance test, pulse wave velocity, and intima-media thickness were evaluated in subjects with prediabetes. PATIENTS: Three hundred eighty subjects without previous history of diabetes were stratified into three groups: controls (n = 99), prediabetes (n = 220), and new-onset type 2 diabetes (n = 61). RESULTS: Subjects with prediabetes exhibited the following: lower esRAGE (0.29 ± 0.18 vs 0.45 ± 0.26 ng/mL; P < .05) and higher S100A12 levels than controls. RT-PCR analysis in mononuclear cells revealed that the mRNA expression level of the esRAGE splice variant progressively decreased in patients with prediabetes and type 2 diabetes with respect to controls. No difference was observed in sRAGE and carboxymethyl-lysine plasma levels between the groups. After multiple regression analyses, only age, HbA1c, and hs-CRP were independently associated with esRAGE levels. Age, HbA1c, and esRAGE were the major determinants of intima-media thickness, whereas S100A12 and systolic blood pressure were the major determinants of pulse wave velocity. When we analyzed the subjects with HbA1c prediabetes (normal fasting glucose/normotolerant and HbA1c 5.7­6.4%), esRAGE and inflammatory markers plasma levels still remained significantly different in respect to controls. CONCLUSIONS: Subjects with HbA1c prediabetes exhibited significantly reduced esRAGE levels and increased levels of markers of inflammation. These alterations are associated with early markers of cardiovascular disease.

Altered expression of uncoupling protein 2 in GLP-1-producing cells after chronic high glucose exposure: implications for the pathogenesis of diabetes mellitus.

Glucagon-like peptide-1 (GLP-1) is a gut L-cell hormone that enhances glucose-stimulated insulin secretion. Several approaches that prevent GLP-1 degradation or activate the GLP-1 receptor are being used to treat type 2 diabetes mellitus (T2DM) patients. In T2DM, GLP-1 secretion has been suggested to be impaired, and this defect appears to be a consequence rather than a cause of impaired glucose homeostasis. However, although defective GLP-1 secretion has been correlated with insulin resistance, little is known about the direct effects of chronic high glucose concentrations, which are typical in diabetes patients, on GLP-1-secreting cell function. In the present study, we demonstrate that glucotoxicity directly affects GLP-1 secretion in GLUTag cells chronically exposed to high glucose. Our results indicate that this abnormality is associated with a decrease in ATP production due to the elevated expression of mitochondrial uncoupling protein 2 (UCP2). Furthermore, UCP2 inhibition using small interfering RNA (siRNA) and the application of glibenclamide, an ATP-sensitive potassium (KATP(+)) channel blocker, reverse the GLP-1 secretion defect induced by chronic high-glucose treatment. These results show that glucotoxicity diminishes the secretory responsiveness of GLP-1-secreting cells to acute glucose stimulation. We conclude that the loss of the incretin effect, as observed in T2DM patients, could at least partially depend on hyperglycemia, which is typical in diabetes patients. Such an understanding may not only provide new insight into diabetes complications but also ultimately contribute to the identification of novel molecular targets within intestinal L-cells for controlling and improving endogenous GLP-1 secretion.

Low circulating vitamin D levels are associated with increased arterial stiffness in prediabetic subjects identified according to HbA1c.

BACKGROUND AND AIMS: We investigated serum -hydroxyvitamin D levels [25(OH)D] and their correlation with early markers of cardiovascular disease in subjects with pre-diabetes. We particularly focused on individuals identified only by glycated hemoglobin A1c (HbA1c 5.7-6.4%) according to the American Diabetes Association criteria but who were normotolerant (NT) after oral glucose tolerance test (OGTT) and had normal fasting glucose (NFG). METHODS: 25(OH)D levels, HbA1c, OGTT, arterial stiffness and intima-media thickness (IMT) were evaluated in 286 subjects without history of diabetes. Subjects were stratified into four groups: controls with HbA1c <5.7%, NFG and NT; prediabetic patients with pre-diabetes according to only HbA1c (HbA1c 5.7-6.4% and NFG/NT); subjects with impaired fasting glucose and impaired glucose tolerance (IFG/IGT); new onset type 2 diabetes (HbA1c ≥ 6.5%). RESULTS: Subjects with NFG/NT and HbA1c 5.7-6.4% (n = 83) showed lower 25(OH)D levels compared with controls (n = 80) (21.7 [15.8-31.1] vs 23.1 [17.1-29.7] ng/mL, P = 0.009); these values were similar to those of the IFG/IGT group and were higher but not significantly different from subjects with new onset type 2 diabetes. After multiple regression analyses, only HbA1c and BMI were independently associated with 25(OH)D levels. Age, HbA1c and 25(OH)D were the major determinants of Augmentation Index. No independent association between 25(OH)D and IMT was found. CONCLUSIONS: Subjects with pre-diabetes (HbA1c 5.7-6.4% and NFG/NT) had significantly reduced 25(OH)D levels compared with controls. Reduction of 25(OH)D levels is inversely associated with arterial stiffness independently of classical risk factors and inflammatory markers. Based on these data, subjects with NFG and NT are not a homogeneous population of patients, and they present different cardiovascular and glycometabolic risks. Our data suggest considering HbA1c as a reliable marker of cardiovascular and metabolic risk independent of fasting and post-load glycemia.

Chronic exposure to GLP-1 increases GLP-1 synthesis and release in a pancreatic alpha cell line (α-TC1): evidence of a direct effect of GLP-1 on pancreatic alpha cells.

AIMS/HYPOTHESIS: Incretin therapies, which are used to treat diabetic patients, cause a chronic supra-physiological increase in GLP-1 circulating levels. It is still unclear how the resulting high hormone concentrations may affect pancreatic alpha cells. The present study was designed to investigate the effects of chronic exposure to high GLP-1 levels on a cultured pancreatic alpha cell line. METHODS: α-TC1-6 cell line was cultured in the presence or absence of GLP-1 (100 nmol/l) for up to 72 h. In our model GLP-1 receptor (GLP-1R) was measured. After the cells were exposed to GLP-1 the levels of glucagon secretion were measured. Because GLP-1 acts on intracellular cAMP production, the function of GLP-1R was studied. We also investigated the effects of chronic GLP-1 exposure on the cAMP/MAPK pathway, Pax6 levels, the expression of prohormone convertases (PCs), glucagon gene (Gcg) and protein expression, glucagon and GLP-1 production. RESULTS: In our model, we were able to detect GLP-1R. After GLP-1 exposure we found a reduction in glucagon secretion. During further investigation of the function of GLP-1R, we found an activation of the cAMP/MAPK/Pax6 pathway and an increase of Gcg gene and protein expression. Furthermore we observed a significant increase in PC1/3 protein expression, GLP-1 intracellular content and GLP-1 secretion. CONCLUSIONS/INTERPRETATION: Our data indicate that the chronic exposure of pancreatic alpha cells to GLP-1 increases the ability of these cells to produce and release GLP-1. This phenomenon occurs through the stimulation of the transcription factor Pax6 and the increased expression of the protein convertase PC1/3.