MASLD, hepatic steatosis and fibrosis are associated with the prevalence of chronic kidney disease and retinopathy in adults with type 1 diabetes mellitus.

AIM: We examined whether metabolic dysfunction-associated steatotic liver disease (MASLD) with or without significant fibrosis (assessed by validated non-invasive biomarkers) was associated with an increased risk of prevalent chronic kidney disease (CKD) or diabetic retinopathy in people with type 1 diabetes mellitus (T1DM). METHODS: We performed a retrospective multicenter cross-sectional study involving 1,409 adult outpatients with T1DM, in whom hepatic steatosis index (HSI) and fibrosis (FIB)-4 index were calculated for non-invasively detecting hepatic steatosis (defined by HSI > 36), with or without coexisting significant fibrosis (FIB-4 index ≥ 1.3 or < 1.3). CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 or urine albumin/creatinine ratio ≥ 3.0 mg/mmol. The presence of diabetic retinopathy was also recorded in all participants. RESULTS: Patients with MASLD and significant fibrosis (n = 93) had a remarkably higher prevalence of CKD and diabetic retinopathy than their counterparts with MASLD without fibrosis (n = 578) and those without steatosis (n = 738). After adjustment for sex, diabetes duration, hemoglobin A1c, hypertension, and use of antihypertensive or lipid-lowering medications, patients with SLD and significant fibrosis had a higher risk of prevalent CKD (adjusted-odds ratio 1.76, 95 % confidence interval 1.05-2.96) than those without steatosis. Patients with MASLD without fibrosis had a higher risk of prevalent retinopathy (adjusted-odds ratio 1.49, 95 % CI 1.13-1.46) than those without steatosis. CONCLUSION: This is the largest cross-sectional study showing that MASLD with and without coexisting significant fibrosis was associated, independently of potential confounders, with an increased risk of prevalent CKD and retinopathy in adults with T1DM.

Association between different modalities of insulin administration and metabolic dysfunction-associated fatty liver disease in adults with type 1 diabetes mellitus.

AIM: We examined whether different insulin administration modalities, i.e., multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII by insulin pumps), are differently associated with the risk of having metabolic dysfunction-associated fatty liver disease (MAFLD), with or without coexisting significant liver fibrosis (assessed by validated non-invasive biomarkers), in adults with type 1 diabetes mellitus (T1DM). METHODS: We conducted a retrospective, multicenter, cross-sectional study involving 1,417 adult individuals with established T1DM treated with MDI or CSII. We calculated hepatic steatosis index (HSI) and fibrosis (FIB)-4 index for non-invasively detecting MAFLD (defined by HSI >36), with or without coexisting significant fibrosis (defined by FIB-4 index ≥ 1.3 or <1.3, respectively). RESULTS: Compared to the MDI group (n = 1,161), insulin-pump users (n = 256; 18.1%) were more likely to be younger (mean age: 40 vs. 48 years, P < 0.001), had better glycemic control (mean hemoglobin A1c: 7.7%  vs. 7.9%, P = 0.025) and a markedly lower prevalence of MAFLD with coexisting significant fibrosis (2.7%  vs. 8.1%, P = 0.010), but a comparable prevalence of MAFLD without fibrosis. In multinomial logistic regression analysis, CSII therapy was associated with a ∼70%-lower risk of MAFLD with significant fibrosis (unadjusted odds ratio 0.32, 95% confidence interval 0.14-0.70; P = 0.004), but this association was no longer significant after adjustment for age, hemoglobin A1c and other potential confounders. CONCLUSION: The lower prevalence of MAFLD with coexisting significant fibrosis we observed in adults with T1DM using CSII therapy, compared to those using MDI therapy, is primarily mediated by inter-group differences in age.

Hepatic steatosis with significant fibrosis is associated with an increased 10-year estimated risk of cardiovascular disease in adults with type 1 diabetes mellitus.

BACKGROUND: We assessed whether hepatic steatosis with or without significant fibrosis (determined by validated non-invasive biomarkers) is associated with an increased 10-year estimated risk for cardiovascular disease (CVD) in people with type 1 diabetes mellitus (T1DM). METHODS: We conducted a retrospective, multicenter, cross-sectional study involving 1,254 adults with established T1DM without pre-existing CVD. We used the hepatic steatosis index (HSI) and fibrosis (FIB)-4 index for non-invasively detecting hepatic steatosis (defined as HSI > 36), with or without coexisting significant fibrosis (defined as FIB-4 index ≥ 1.3 or < 1.3). We calculated the Steno type 1 risk engine and the atherosclerotic CVD (ASCVD) risk score to estimate the 10-year risk of developing a first fatal or nonfatal CVD event. RESULTS: Using the Steno type 1 risk engine, a significantly greater proportion of patients with hepatic steatosis and significant fibrosis (n = 91) had a high 10-year estimated CVD risk compared to those with hepatic steatosis alone (n = 509) or without steatosis (n = 654) (75.8% vs. 23.2% vs. 24.9%, p < 0.001). After adjustment for sex, BMI, diabetes duration, hemoglobin A1c, chronic kidney disease, and lipid-lowering medication use, patients with hepatic steatosis and significant fibrosis had an increased 10-year estimated risk of developing a first fatal or nonfatal CVD event (adjusted-odds ratio 11.4, 95% confidence interval 3.54-36.9) than those without steatosis. We observed almost identical results using the ASCVD risk calculator. CONCLUSIONS: The 10-year estimated CVD risk is remarkably greater in T1DM adults with hepatic steatosis and significant fibrosis than in their counterparts with hepatic steatosis alone or without steatosis.

Glucose-lowering drugs with cardiovascular benefits as modifiers of critical elements of the human life history.

The life history theory assumes that all organisms are under selective pressure to harvest external resources and allocate them to maximise fitness: only organisms making the best use of energy obtain the greatest fitness benefits. The trade-off of energy spans four functions: maintenance, growth, reproduction, and defence against pathogens. The innovative antihyperglycaemic agents glucagon-like peptide 1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 (SGLT2) inhibitors decrease bodyweight and have the potential to counter low-grade inflammation. These key activities could rewire two components of the life history theory operative in adulthood-ie, maintenance and defence. In this Personal View, we postulate that the benefits of these medications on the cardiovascular system, beyond their glucose-lowering effects, could be mediated by the reduction of the maintenance cost driven by obesity and efforts spent on blunting low-grade inflammation.

Telemedicine for the Clinical Management of Diabetes; Implications and Considerations After COVID-19 Experience.

Telemedicine is a clinical approach that was seldom used in the day-to-day practice, if not only in certain settings, before the COVID-19 pandemic. As stated by the WHO, telemedicine is: the delivery of health care services, where distance is a critical factor, by all health care professionals using information and communication technologies (ICT) for the exchange of valid information for diagnosis, treatment and prevention of disease and injuries, …. Telemedicine has actually represented the most useful and employed tool to maintain contacts between patients and physicians during the period of physical distance imposed by the pandemic, especially during the lockdown. Diabetes in particular, a chronic disease that often needs frequent confronting between patient and health professionals has taken advantage of the telehealth approach. Nowadays, technological tools are more and more widely used for the management of diabetes. In this review results obtained by telemendicine application in type 1 and type 2 diabetic individuals during COVID-19 are revised, and future perspectives for telemedicine use to manage diabetes are discussed.

Recommendations for Cardiovascular Prevention During the Sars-Cov-2 Pandemic: An Executive Document by the Board of the Italian Society of Cardiovascular Prevention.

In 2020, the Sars-Cov-2 pandemic is causing a huge and dramatic impact on healthcare systems worldwide. During this emergency, fragile patients suffering from other comorbidities, especially patients susceptible to or affected by cardiovascular disease, are the ones most exposed to the poorer outcomes. Therefore, it is still mandatory to continue to strictly adhere to the rules of cardiovascular prevention. This document aims to provide all doctors with simple and clear recommendations in order to spread useful messages to the widest number of subjects in order to continue the battle against cardiovascular diseases even in times of pandemic.

[Consensus document and recommendations for the prevention of cardiovascular disease in Italy - 2018]. / Documento di consenso e raccomandazioni per la prevenzione cardiovascolare in Italia 2018.

Cardiovascular prevention represents a cornerstone of modern strategies to reduce the burden of cardiovascular disease. It is of key importance to prevent cardiovascular diseases and associated events, not only to reduce morbidity and mortality, but also to increase the years of wellness in the aging population and to make the growing socio-economic burden imposed by cardiovascular events more sustainable.The current approach to prevention is based on an integrated use of effective lifestyle measures and, whenever appropriate, of antihypertensive and antidiabetic drugs, lipid-lowering agents and antiplatelet drugs.Given that population characteristics, in terms of ethnicity, demography and lifestyle habits, and healthcare system organizations differ among countries, international guidelines are not always applicable to specific countries and, often, are difficult to translate into daily clinical practice.In order to afford the specific features of Italy, 10 Scientific Societies and Research Institutions, mostly involved in preventive strategies, contributed to the present Italian consensus document, which includes brief, practical recommendations to support the preventive actions within the physician community and the general practice setting.

The impact of glucose-lowering medications on cardiovascular disease.

Patients with type 2 diabetes mellitus die most frequently from cardiovascular disease. Metabolic control is mandatory both for preventing long-term complications and for reducing the negative effects of the exposure of the other risk factors. In this article, we will describe the most commonly used glucose-lowering agents, the pathophysiological mechanisms underlying their cardiovascular protection, the available evidence-based data for this protection, and the contraindications and potential adverse effects.

Circulating levels and characterization of microparticles in patients with different degrees of glucose tolerance.

BACKGROUND: Microparticles (MPs) are vesicular structures shed from endothelial or circulating blood cells, after activation or apoptosis, and can be considered markers of vascular damage. We aimed to determine the levels of circulating MPs, their content of miRNA-126-3p and 5p, and their relationship with early endothelial activation/damage, in patients with different degree of glucose tolerance. METHODS: CD62E+, CD62P+, CD142+, CD45+ circulating MPs, their apoptotic (AnnexinV+) fractions, and miRNA-126 expression were determined in 39 prediabetic (PreDM), 68 type 2 diabetic (T2DM), and 53 control (NGT) subjects, along with main anthropometric and biochemical measurements. MPs were analysed by flow cytometry. miRNA-126 was measured by quantitative real-time PCR. Plasma antioxidant capacity was determined by electronic spin resonance; ICAM-1, and VCAM-1 by ELISA. RESULTS: Activated endothelial cell-derived MPs (CD62E+) were significantly increased in PreDM and T2DM in comparison to NGT (p < 0.0001). AnnexinV+/CD62E+ MPs and Annexin V+ MPs were significantly increased in T2DM compared to PreDM and NGT (p < 0.001); other MPs were not significantly different among groups. Plasma antioxidant capacity was significantly decreased in PreDM and T2DM compared to NGT (p = 0.001); VCAM-1 significantly increased in PreDM and T2DM in comparison to NGT (p = 0.001). miR-126-3p expression, but not miR-126-5p, in MPs, decreased significantly and progressively from NGT, to PreDM, and T2DM (p < 0.001). In PreDM and T2DM, CD62E+ MPs level was significantly and negatively associated with plasma glucose (p = 0.004). CONCLUSION: We show for the first time that circulating CD62E+ MPs level and miR-126-3p content in MPs are abnormal in subjects with pre-diabetes; the content of miR-126-3p correlates with markers of endothelial inflammation, such as VCAM-1, plasma antioxidant capacity, and microparticles, well-accepted markers of endothelial dysfunction.

Hypovitaminosis D is associated with erectile dysfunction in type 2 diabetes.

Diabetes is an established risk factor for erectile dysfunction (ED). The pathophysiology of ED in diabetic men is multifactorial, but it mainly involves a vascular disorder related to a reduction of endothelial function. Recently, several studies have correlated ED risk factors with vitamin D deficiency. In this study, we evaluate the relationship between 25-hydroxyvitamin D [25(OH)D] levels, erectile dysfunction, and vascular disease, in type 2 diabetes mellitus men (T2DM). In this observational study, 92 T2DM males (58.83 ± 9.73 years) underwent medical history collection, International Index of Erectile Function (IIEF-5) questionnaire, that allows the identification and grading of DE, physical examination, biochemical/hormonal blood tests, and penile echo-color Doppler ultrasonography. T2DM patients with lower 25(OH)D levels (<25 nmol/l) showed higher penile IMT (p < 0.05), waist circonference (p < 0.05), glucose concentrations (p < 0.05), and lower IIEF-5 score (p < 0.005), testosterone concentrations (p < 0.05), and cavernous peak systolic velocity (PSV) (p < 0.05), compared to patients with 25(OH)D >50 nmol/l. 25(OH)D levels were directly correlated with IIEF-5 (R = 0.39; p = 0.0001), testosterone (R = 0.24; p = 0.02), and PSV (R = 0.24; p = 0.04) and inversely with waist (R = -0.33; p = 0.002), HbA1c (R = -0.22; p = 0.03), triglyceride (R = -0.21; p = 0.06), and penile IMT (R = -0.30; p = 0.009). At multivariate analysis, 25(OH)D deficiency remained an independent predictor of DE. We demonstrate a significant association between 25(OH)D deficiency and erectile dysfunction in T2DM men. This association may be due to the influence of 25(OH)D deficiency on cardiovascular risk factor (glycaemia, HDL cholesterol, and triglycerides), testosterone plasma levels and endothelial dysfunction.

NAD(+)-dependent SIRT1 deactivation has a key role on ischemia-reperfusion-induced apoptosis.

Ischemia-reperfusion (IR) leads to severe organ injury and dysfunction. Sirtuins (SIRTs) are a family of histone deacetylases (HDACs) that require nicotinamide adenine dinucleotide (NAD(+)) for the deacetylation reaction. SIRTs play a major role in counteracting cellular stress and apoptosis. This study aimed to investigate the mechanisms of heart protection against apoptosis by SIRTs and the molecular pathways involved in SIRTs regulation and function in a rat model of IR injury. Hearts of male Wistar-Kyoto rats were subjected to 30-min ischemia followed by reperfusion up to 6h. IR increased cardiomyocyte apoptosis; the cleavage of caspase 3, induced a transient upregulation of SIRT1 and downregulation of SIRT6 expression, but decreased SIRT1 activity and reduced NAD(+) content. IR also increased forkhead box protein O1 (FoxO1) expression and FoxO1 binding to SIRT1 promoter region. Resveratrol restored SIRT1 activity and NAD(+) level by an AMPK-dependent mechanism, reduced cardiomyocyte apoptosis, and attenuated caspase 3 cleavage via heat shock factor-1 deacetylation and heat shock protein (HSP) expression upregulation. Our data show new potential molecular mechanisms of up and downstream regulation of SIRT1 in IR. The interplay among FoxO1, SIRT1, NAD(+), AMPK, HSP, and SIRT6 depicts a complex molecular network that protects the heart from apoptosis during IR and may be susceptible to therapeutic interventions.

Endothelial progenitor cells are reduced in acromegalic patients and can be restored by treatment with somatostatin analogs.

CONTEXT: Acromegaly increases cardiovascular risk, possibly due to the high prevalence of classical risk factors. However, in vitro studies show a protective role of GH/IGF-1 on the endothelium. OBJECTIVE: The objective of the study was to investigate circulating endothelial progenitor cells (EPCs), a marker of vascular regeneration, in acromegalic patients and how they are affected by acromegaly treatment. DESIGN: This was a cross-sectional case-control and observational study. SETTING: The study was conducted at a tertiary ambulatory referral endocrinology center. PATIENTS: Forty-three acromegalic patients (26 active; 17 inactive) and 43 control subjects matched by age, gender, and degree of glucose tolerance participated in the study. INTERVENTION: Circulating EPCs were quantified by flow cytometry based on the expression of CD34, CD133, and kinase insert domain-containing receptor (KDR). Nine patients with active acromegaly were reevaluated after 24 weeks of treatment with somatostatin analogs (SSAs). MAIN OUTCOME MEASURE: Differences in EPC levels between patients and controls were measured. RESULTS: Acromegalic patients showed a significant reduction of the total CD34(+)KDR(+) EPC population compared with controls, which was more evident in patients without diabetes or hypertension. More definite CD34(+)CD133(+)KDR(+) EPCs were reduced in patients with active compared with those with inactive acromegaly and compared with controls. The number of CD34(+)CD133(+)KDR(+) EPCs correlated with IGF-1 levels (r = -0.45; P < .001), fasting plasma glucose (r = -0.40; P = .004), and the homeostasis model assessment index of insulin resistance (r = -0.32; P = .026). CD34(+)CD133(+)KDR(+) EPCs increased 2-fold after SSA treatment. CONCLUSIONS: Acromegalic patients have a reduced endothelial regenerative capacity, possibly due to activation of the GH/IGF-1, rather than concomitant risk factors. Treatment with SSAs can restore immature EPCs to normal levels.

Sirtuin 1 stabilization by HuR represses TNF-α- and glucose-induced E-selectin release and endothelial cell adhesiveness in vitro: relevance to human metabolic syndrome.

Chronic inflammation and hyperglycaemia, typical features of metabolic diseases, trigger endothelial damage and release of E-selectin, a marker of endothelial activation. In the present study, we investigated molecular pathways involved in the regulation of endothelial cell activation induced by tumour necrosis factor-α (TNF-α) and high glucose. In cultured human umbilical vein endothelial cells (HUVECs), we studied the role of HuR, an ELAV (embryonic lethal, abnormal vision, Drosophila) family RNA-binding protein, and Sirtuin 1 (SIRT1) on E-selectin release and cell adhesion at different glucose concentrations. HuR expression and binding to SIRT1 were also analysed ex vivo in peripheral blood mononuclear cells (PBMCs) of subjects with and without the metabolic syndrome (MS), by immunoprecipitation (IP) of the ribonucleoprotein (RNP) complex. We found that SIRT1 overexpression prevented TNF-α- and high-glucose-dependent nuclear factor-κB (NF-κB)-p65 acetylation, E-selectin promoter activity, E-selectin release and adhesion of THP-1 cells to HUVECs. The same was mimicked by HuR overexpression, which binds and stabilizes SIRT1 mRNA. Importantly, in PBMCs of individuals with MS compared with those without, SIRT1 expression was lower, and the ability of HuR to bind SIRT1 mRNA was significantly reduced, while plasma E-selectin was increased. We conclude that post-transcriptional stabilization of SIRT1 by HuR represses inflammation- and hyperglycaemia-induced E-selectin release and endothelial cell activation. Therefore, increasing SIRT1 expression represents a strategy to counter the accelerated vascular disease in metabolic disorders.

Elevated white blood cell count is associated with prevalence and development of the metabolic syndrome and its components in the general population.

The metabolic syndrome (MS) is characterized by chronic inflammation. We aimed to determine the association of white blood cell (WBC) count with prevalence and development of the MS and its components in the general population. A cohort of 1,329 subjects from the local working population aged 41.3 ± 7.5 years and recruited since 2000-2008 was followed up for 4.0 ± 1.2 years. WBC count and MS components were determined at baseline and follow-up. To determine whether WBC predicted incident MS, we used a logistic regression analysis adjusted for demographics, baseline variables that define MS components, smoke, medications, and follow-up duration. Cross-sectionally in the whole population, WBC count increased in parallel with the number of MS components in the same individual, and the presence of each component was associated with higher WBC count. Baseline WBC count was significantly higher in subjects with prevalent MS. Among subjects without MS at baseline, those who developed MS had significantly higher WBC than those who did not develop MS at follow-up. Development of each MS component was associated with increased WBC count. WBC count remained significantly associated with MS development after correction for several potential confounders (OR for 1 SD increase in WBC 1.26; 95 % CI 1.01-1.58). In conclusion, elevated WBC is intimately linked to the prevalence and future development of the MS in a young population of working subjects.

Procalcific phenotypic drift of circulating progenitor cells in type 2 diabetes with coronary artery disease.

Diabetes mellitus (DM) alters circulating progenitor cells relevant for the pathophysiology of coronary artery disease (CAD). While endothelial progenitor cells (EPCs) are reduced, there is no data on procalcific polarization of circulating progenitors, which may contribute to vascular calcification in these patients. In a cohort of 107 subjects with and without DM and CAD, we analyzed the pro-calcific versus endothelial differentiation status of circulating CD34+ progenitor cells. Endothelial commitment was determined by expression of VEGFR-2 (KDR) and pro-calcific polarization by expression of osteocalcin (OC) and bone alkaline phosphatase (BAP). We found that DM patients had significantly higher expression of OC and BAP on circulating CD34+ cells than control subjects, especially in the presence of CAD. In patients with DM and CAD, the ratio of OC/KDR, BAP/KDR, and OC+BAP/KDR was about 3-fold increased than in other groups. EPCs cultured from DM patients with CAD occasionally formed structures highly suggestive of calcified nodules, and the expression of osteogenic markers by EPCs from control subjects was significantly increased in response to the toll-like receptor agonist LPS. In conclusion, circulating progenitor cells of diabetic patients show a phenotypic drift toward a pro-calcific phenotype that may be driven by inflammatory signals.

Characteristics and outcomes of the hyperglycemic hyperosmolar non-ketotic syndrome in a cohort of 51 consecutive cases at a single center.

AIMS: The hyperglycemic hyperosmolar syndrome (HHS) is a life-threatening diabetic complication. We aimed to portrait the short and long term outcome after a HHS episode and to describe features associated with increased early mortality. METHODS: We collected data from consecutive HHS cases, defined based on rigorous glucose and osmolality criteria. We retrieved anthropometric measures, history of diabetes, other cardiovascular risk factors and chronic co-morbidity. Clinical and biochemical parameters were recorded at admission, after 24h and at discharge. We assessed incidence of complications, as well as short (≤ 30 days) and long term mortality. RESULTS: Patients were about 80-year old. Fifty-one cases were included, characterized by severe hyperglycemia (55.5 mosm/L) and hyperosmolality (385 mosm/L). Thirty-three percent developed at least one complication. Short term mortality was 16%; lower Glasgow Coma Scale, higher plasma glucose and mild acidosis were predictive of short term mortality. The long term mortality (median follow-up 1.27 years) was not significantly different from historical mortality data after hypoglycemic coma. CONCLUSION: In this study, early mortality of HHS was 16% and some clinical features at presentation were predictive of an adverse short term outcome. Long term survival after a HHS episode did not appear to be severely impaired.

Hemodynamics assessed via approximate entropy analysis of impedance cardiography time series: effect of metabolic syndrome.

The metabolic syndrome (MS), a predisposing condition for cardiovascular disease, presents disturbances in hemodynamics; impedance cardiography (ICG) can assess these alterations. In subjects with MS, the morphology of the pulses present in the ICG time series is more irregular/complex than in normal subjects. Therefore, the aim of the present study was to quantitatively assess the complexity of ICG times series in 53 patients, with or without MS, through a nonlinear analysis algorithm, the approximate entropy, a method employed in recent years for the study of several biological signals, which provides a scalar index, ApEn. We correlated ApEn computed from ICG times series data during fasting and postprandial phase with the presence of alterations in the parameters defining MS [Adult Treatment Panel (ATP) III (Grundy SM, Brewer HB Jr, Cleeman JI, Smith SC Jr, Lenfant C; National Heart, Lung, and Blood Institute; American Heart Association. Circulation 109: 433-438, 2004) and the International Diabetes Federation (IDF) definition]. Results show that ApEn was significantly higher in subjects with MS compared with those without (1.81 ± 0.09 vs. 1.65 ± 0.13; means ± SD; P = 0.0013, with ATP III definition; 1.82 ± 0.09 vs. 1.67 ± 0.12; P = 0.00006, with the IDF definition). We also demonstrated that ApEn increase parallels the number of components of MS. ApEn was then correlated to each MS component: mean ApEn values of subjects belonging to the first and fourth quartiles of the distribution of MS parameters were statistically different for all parameters but HDL cholesterol. No difference was observed between ApEn values evaluated in fasting and postprandial states. In conclusion, we identified that MS is characterized by an increased complexity of ICG signals: this may have a prognostic relevance in subjects with this condition.

The metabolic syndrome influences the response to incretin-based therapies.

We hypothesize that type 2 diabetic patients with different phenotypes may show different response to incretin-based therapies. Therefore, we tested whether the presence of metabolic syndrome (MS) influences glycemic response to these drugs. We prospectively followed 211 patients, treated with the GLP-1 analog exenatide (n = 102) or a DPP-4 inhibitor (n = 109) for at least 4 months. Treatment was decided on clinical grounds. We collected baseline data (age, sex, BMI, waist, systolic and diastolic blood pressure, lipid profile, data on diabetic complications and concomitant treatment) and HbA1c at subsequent visits. Patients were divided into groups according to the presence/absence of MS. Compared to patients on exenatide, patients on DPP-4 inhibitors were older and had lower BMI, waist, diastolic blood pressure, fasting plasma glucose, and HbA1c. At means of baseline values, HbA1c reduction was similar in patients treated with exenatide or DPP-4 inhibitors. Patients on exenatide showed significantly higher HbA1c reduction if they had MS (-1.55 ± 0.22%; n = 88) than if they had not (-0.34 ± 0.18%; P = 0.002). Conversely, patients on DPP-4 inhibitors showed significantly lower HbA1c reduction if they had MS (-0.60 ± 0.12%; n = 73) than if they had not (-1.50 ± 0.24%; P < 0.001). Type of MS definition (ATP-III, IDF or WHO) poorly influenced these trends. The interaction between type of therapy (exenatide vs. DPP-4 inhibitors) and MS remained significant after adjusting for age, baseline HbA1c, BMI, and concomitant medications. In conclusion, the presence of MS appears to modify the response to incretin-based therapies. Given the non-randomized nature of this study, these data need to be replicated.

Downregulation of the longevity-associated protein sirtuin 1 in insulin resistance and metabolic syndrome: potential biochemical mechanisms.

OBJECTIVE: Sirtuins (SIRTs) are NAD(+)-dependent deacetylases that regulate metabolism and life span. We used peripheral blood mononuclear cells (PBMCs) to determine ex vivo whether insulin resistance/metabolic syndrome influences SIRTs. We also assessed the potential mechanisms linking metabolic alterations to SIRTs in human monocytes (THP-1) in vitro. RESEARCH DESIGN AND METHODS: SIRT1-SIRT7 gene and protein expression was determined in PBMCs of 54 subjects (41 with normal glucose tolerance and 13 with metabolic syndrome). Insulin sensitivity was assessed by the minimal model analysis. Subclinical atherosclerosis was assessed by carotid intima-media thickness (IMT). In THP-1 cells exposed to high glucose or fatty acids in vitro, we explored SIRT1 expression, p53 acetylation, Jun NH(2)-terminal kinase (JNK) activation, NAD(+) levels, and nicotinamide phosphoribosyltransferase (NAMPT) expression. The effects of SIRT1 induction by resveratrol and of SIRT1 gene silencing were also assessed. RESULTS: In vivo, insulin resistance and metabolic syndrome were associated with low PBMC SIRT1 gene and protein expression. SIRT1 gene expression was negatively correlated with carotid IMT. In THP-1 cells, high glucose and palmitate reduced SIRT1 and NAMPT expression and reduced the levels of intracellular NAD(+) through oxidative stress. No effect was observed in cells exposed to linoleate or insulin. High glucose and palmitate increased p53 acetylation and JNK phosphorylation; these effects were abolished in siRNA SIRT1-treated cells. Glucose- and palmitate-mediated effects on NAMPT and SIRT1 were prevented by resveratrol in vitro. CONCLUSIONS: Insulin resistance and subclinical atherosclerosis are associated with SIRT1 downregulation in monocytes. Glucotoxicity and lypotoxicity play a relevant role in quenching SIRT1 expression.