Methylglyoxal, a Highly Reactive Dicarbonyl Compound, in Diabetes, Its Vascular Complications, and Other Age-Related Diseases.

The formation and accumulation of methylglyoxal (MGO), a highly reactive dicarbonyl compound, has been implicated in the pathogenesis of type 2 diabetes, vascular complications of diabetes, and several other age-related chronic inflammatory diseases such as cardiovascular disease, cancer, and disorders of the central nervous system. MGO is mainly formed as a byproduct of glycolysis and, under physiological circumstances, detoxified by the glyoxalase system. MGO is the major precursor of nonenzymatic glycation of proteins and DNA, subsequently leading to the formation of advanced glycation end products (AGEs). MGO and MGO-derived AGEs can impact on organs and tissues affecting their functions and structure. In this review we summarize the formation of MGO, the detoxification of MGO by the glyoxalase system, and the biochemical pathways through which MGO is linked to the development of diabetes, vascular complications of diabetes, and other age-related diseases. Although interventions to treat MGO-associated complications are not yet available in the clinical setting, several strategies to lower MGO have been developed over the years. We will summarize several new directions to target MGO stress including glyoxalase inducers and MGO scavengers. Targeting MGO burden may provide new therapeutic applications to mitigate diseases in which MGO plays a crucial role.

Different Measures of Hyperglycemia Are Negatively Associated With Skin Microvascular Flowmotion: The Maastricht Study.

OBJECTIVE: Diabetes can lead to microvascular complications such as diabetic neuropathy, nephropathy, and retinopathy. Hyperglycemia may initiate microvascular function impairment early in the course of diabetes, even prior to its clinical establishment during the pre-diabetes stage. Microvascular vasomotion, that is, the rhythmic arteriolar constriction and dilation, is an important function that regulates oxygen and nutrient delivery within the tissue and regulates peripheral resistance. Using laser Doppler flowmetry (LDF), vasomotion in skin microcirculation can be measured as flowmotion. Changes in flowmotion have been shown in individuals with obesity, and type 1 or type 2 diabetes mellitus. However, no data are available on associations between hyperglycemia and flowmotion in the general population. Our aim was to study whether measures of hyperglycemia were associated with different components of skin microvascular flowmotion (SMF) in a population-based cohort (The Maastricht Study). METHODS: Data from 7293 participants of The Maastricht Study were used. SMF was measured using LDF. Endothelial, neurogenic and myogenic component SMF power were used as dependent variables. We investigated the associations of glucose metabolism status (normal glucose metabolism, prediabetes, and type 2 diabetes mellitus), measures of hyperglycemia (fasting plasma glucose [FPG], 2-h post-load glucose [2 h-PG], HbA1c, advanced glycation end-products [AGEs] assessed as skin autofluorescence [SAF]), and indices of glucose variability (incremental glucose peak [IGP] and continuous glucose monitoring [CGM] -assessed as standard deviation [SD]) with each component of SMF power. We used linear regression analyses with adjustments for confounders, and trend analyses. RESULTS: We observed consistent negative associations between HbA1c levels and all three (endothelial, neurogenic, and myogenic) skin microvascular flowmotion (SMF) powers in the additionally adjusted model. Similarly, in the conservative model, we found that multiple hyperglycemia metrics such as GMS trend, PreD, T2DM, FPG, 2 h-PG, and HbA1c were consistently negatively associated with all three SMF powers. CONCLUSIONS: We showed that skin microvascular flowmotion is reduced in individuals with (pre)diabetes. In addition, different measures of hyperglycemia are negatively associated with skin microvascular flowmotion.

Increased accumulation of the advanced glycation endproduct Ne(carboxymethyl) lysine in the intramyocardial vasculature in patients with epicarditis.

Advanced glycation end-products (AGEs) are implicated in the pathogenesis of vascular disease. In previous studies we have found increased deposition of N(e)-(carboxymethyl)lysine (CML) in intramyocardial vasculature in the heart in acute myocardial infarction and myocarditis. It is known that the process of inflammation plays a role in the formation of AGEs. In this study we have explored the presence of CML (a major AGE) in the heart of patients with epicarditis using a monoclonal anti-CML antibody. Nine patients with epicarditis (n = 9) died and their hearts were used for this study, control were hearts from patients who died from conditions unrelated to heart disease and without signs of myocarditis or epicarditis CML deposition and complement were significantly increased in patients with epicarditis compared to control hearts. Thus epicarditis increases CML depositions in the intramyocardial vasculature.

Serum sex hormone-binding globulin levels are reduced and inversely associated with intrahepatic lipid content and saturated fatty acid fraction in adult patients with glycogen storage disease type 1a.

PURPOSE: De novo lipogenesis has been inversely associated with serum sex hormone-binding globulin (SHBG) levels. However, the directionality of this association has remained uncertain. We, therefore, studied individuals with glycogen storage disease type 1a (GSD1a), who are characterized by a genetic defect in glucose-6-phosphatase resulting in increased rates of de novo lipogenesis, to assess the downstream effect on serum SHBG levels. METHODS: A case-control study comparing serum SHBG levels in patients with GSD1a (n = 10) and controls matched for age, sex, and BMI (n = 10). Intrahepatic lipid content and saturated fatty acid fraction were quantified by proton magnetic resonance spectroscopy. RESULTS: Serum SHBG levels were statistically significantly lower in patients with GSD1a compared to the controls (p = 0.041), while intrahepatic lipid content and intrahepatic saturated fatty acid fraction-a marker of de novo lipogenesis-were significantly higher in patients with GSD1a (p = 0.001 and p = 0.019, respectively). In addition, there was a statistically significant, inverse association of intrahepatic lipid content and saturated fatty acid fraction with serum SHBG levels in patients and controls combined (ß: - 0.28, 95% CI: - 0.47;- 0.09 and ß: - 0.02, 95% CI: - 0.04;- 0.01, respectively). CONCLUSION: Patients with GSD1a, who are characterized by genetically determined higher rates of de novo lipogenesis, have lower serum SHBG levels than controls.

Irbesartan treatment does not influence plasma levels of the dicarbonyls methylglyoxal, glyoxal and 3-deoxyglucosone in participants with type 2 diabetes and microalbuminuria: An IRMA2 sub-study.

AIM: Angiotensin receptor blockers (ARBs) reduce vascular complications in diabetes independently of blood pressure. Experimental studies suggested that ARBs may restore the detoxifying enzyme glyoxalase 1, thereby lowering dicarbonyls such as methylglyoxal. Human data on the effects of ARBs on plasma dicarbonyl levels are lacking. We investigated, in individuals with type 2 diabetes, whether irbesartan lowered plasma levels of the dicarbonyls methylglyoxal, glyoxal, 3-deoxyglucosone and their derived advanced glycation end products (AGEs), and increased d-lactate, reflecting greater methylglyoxal flux. METHODS: We analysed a subset of the Irbesartan in Patients with T2D and Microalbuminuria (IRMA2) study. We measured plasma dicarbonyls methylglyoxal, glyoxal and 3-deoxyglucosone, free AGEs and d-lactate using ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) in the treatment arm receiving 300 mg irbesartan (n = 121) and a placebo group (n = 101) at baseline and after 1 and 2 years. Effect of treatment was analysed with repeated measurements ANOVA. RESULTS: There was a slight, but significant difference in baseline median methylglyoxal levels [placebo 1119 (907-1509) nmol/l vs. irbesartan 300 mg 1053 (820-1427) nmol/l], but no significant changes were observed in any of the plasma dicarbonyls over time in either group and there was no effect of irbesartan treatment on plasma free AGEs or d-lactate levels at either 1 or 2 years. CONCLUSION: Irbesartan treatment does not change plasma levels of the dicarbonyls methylglyoxal, glyoxal and 3-deoxyglucosone, free AGEs or d-lactate in type 2 diabetes. This indicates that increased dicarbonyls in type 2 diabetes are not targetable by ARBs, and other approaches to lower systemic dicarbonyls are needed in type 2 diabetes. (Clinical Trial Registry No: #NCT00317915).

Dietary intake of advanced glycation end products (AGEs) and changes in body weight in European adults.

PURPOSE: Advanced glycation end products (AGEs) can be formed in foods by the reaction of reducing sugars with proteins, and have been shown to induce insulin resistance and obesity in experimental studies. We examined the association between dietary AGEs intake and changes in body weight in adults over an average of 5 years of follow-up. METHODS: A total of 255,170 participants aged 25-70 years were recruited in ten European countries (1992-2000) in the PANACEA study (Physical Activity, Nutrition, Alcohol, Cessation of smoking, Eating out of home in relation to Anthropometry), a sub-cohort of the EPIC (European Prospective Investigation into Cancer and Nutrition). Body weight was measured at recruitment and self-reported between 2 and 11 years later depending on the study center. A reference database for AGEs was used containing UPLC-MS/MS-measured Nε-(carboxymethyl)-lysine (CML), Nε-(1-carboxyethyl)-lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) in 200 common European foods. This reference database was matched to foods and decomposed recipes obtained from country-specific validated dietary questionnaires in EPIC and intake levels of CEL, CML, and MG-H1 were estimated. Associations between dietary AGEs intake and body weight change were estimated separately for each of the three AGEs using multilevel mixed linear regression models with center as random effect and dietary AGEs intake and relevant confounders as fixed effects. RESULTS: A one-SD increment in CEL intake was associated with 0.111 kg (95% CI 0.087-0.135) additional weight gain over 5 years. The corresponding additional weight gain for CML and MG-H1 was 0.065 kg (0.041-0.089) and 0.034 kg (0.012, 0.057), respectively. The top six food groups contributing to AGEs intake, with varying proportions across the AGEs, were cereals/cereal products, meat/processed meat, cakes/biscuits, dairy, sugar and confectionary, and fish/shellfish. CONCLUSION: In this study of European adults, higher intakes of AGEs were associated with marginally greater weight gain over an average of 5 years of follow-up.

Alcohol and red wine consumption, but not fruit, vegetables, fish or dairy products, are associated with less endothelial dysfunction and less low-grade inflammation: the Hoorn Study.

PURPOSE: Endothelial dysfunction and low-grade inflammation are key phenomena in the pathobiology of cardiovascular disease (CVD). Their dietary modification might explain the observed reduction in CVD that has been associated with a healthy diet rich in fruit, vegetables and fish, low in dairy products and with moderate alcohol and red wine consumption. We investigated the associations between the above food groups and endothelial dysfunction and low-grade inflammation in a population-based cohort of Dutch elderly individuals. METHODS: Diet was measured by food frequency questionnaire (n = 801; women = 399; age 68.5 ± 7.2 years). Endothelial dysfunction was determined (1) by combining von Willebrand factor, and soluble intercellular adhesion molecule 1 (sICAM-1), vascular cell adhesion molecule 1, endothelial selectin and thrombomodulin, using Z-scores, into a biomarker score and (2) by flow-mediated vasodilation (FMD), and low-grade inflammation by combining C-reactive protein, serum amyloid A, interleukin 6, interleukin 8, tumour necrosis factor α and sICAM-1 into a biomarker score, with smaller FMD and higher scores representing more dysfunction and inflammation, respectively. We used linear regression analyses to adjust associations for sex, age, energy, glucose metabolism, body mass index, smoking, prior CVD, educational level, physical activity and each of the other food groups. RESULTS: Moderate [ß (95% CI) -0.13 (-0.33; 0.07)] and high [-0.22 (-0.45; -0.003)] alcohol consumption, and red wine [-0.16 (-0.30; -0.01)] consumption, but none of the other food groups, were associated with a lower endothelial dysfunction biomarker score and a greater FMD. The associations for FMD were, however, not statistically significant. Only red wine consumption was associated with a lower low-grade inflammation biomarker score [-0.18 (-0.33; -0.04)]. CONCLUSIONS: Alcohol and red wine consumption may favourably influence processes involved in atherothrombosis.

Association between bone metabolism regulators and arterial stiffness in type 2 diabetes patients.

BACKGROUND AND AIM: Osteopontin (OPN), osteonectin (ON) and osteocalcin (OC) play an important role in the development of vascular calcifications, but it is unclear whether these bone metabolism regulators contribute to the development of arterial stiffness in type 2 diabetes patients. We therefore aim to determine the relationship between plasma concentrations of OPN, ON, OC and arterial stiffness in type 2 diabetes patients. METHODS: Cross-sectional study of 1003 type 2 diabetes patients included in the Second Manifestations of ARTerial disease (SMART)-cohort. Generalized linear models were used to evaluate the relation between plasma levels of OPN, ON and OC and arterial stiffness as measured by pulse pressure (PP), ankle-brachial index (ABI) (≥0.9), carotid artery distension and an arterial stiffness summary score. Analyses were adjusted for age, sex, kidney function, diabetes duration and diastolic blood pressure. Higher OPN plasma levels were significantly related to a lower ABI (ß-0.013; 95%CI -0.024 to -0.002) and a higher arterial stiffness summary score (OR1.24; 95%CI 1.03-1.49). OPN levels were not related to PP (ß 0.59; 95%CI -0.63-1.81) or absolute carotid artery distention (ß -7.03; 95%CI -20.00-5.93). ON and OC plasma levels were not related to any of the arterial stiffness measures. CONCLUSION: Only elevated plasma levels of OPN are associated with increased arterial stiffness in patients with type 2 diabetes as measured by the ankle-brachial index and arterial stiffness summary score. These findings indicate that OPN may be involved in the pathophysiology of arterial stiffness and call for further clinical investigation.

The journey of adult psoriasis patients towards biologics: past and present - Results from the BioCAPTURE registry.

BACKGROUND: A considerable disease period often precedes initiation of a biologic in patients with psoriasis. Little is known about this important period in patients' lives. Evaluation of this 'journey' can reveal important insights and opportunities for physicians and healthcare decision makers. OBJECTIVES: (i) To describe patient and treatment characteristics until the start of biologic treatment in patients with severe psoriasis, (ii) to assess shifts in early (2005-2009) versus established (2010-2015) biologics prescription periods, (iii) to assess changes in hospital/day care admissions before vs. after starting biologics. METHODS: Explorative, retrospective study on the treatment characteristics of the disease period until first biologic, presented with descriptive statistics of patients included in the BioCAPTURE registry. Journeys of 2005-2009 and 2010-2015 were compared with statistical tests to identify important shifts. RESULTS: Median TUS (time until conventional systemic) was 11.0 years and median TUB (time until biologic) was 18.9 years for all patients treated from 2005 to 2015. Most patients received three different conventional antipsoriatic systemic therapies. We noticed a small trend towards a shorter journey (TUB) with only two conventional systemic agents instead of three before initiating a biologic in later years (2010-2015, vs. 2005-2009). We also noticed a significant decrease in (day care) admissions comparing the two years before, versus the first two years after the start of a biologic treatment (17.7 vs. 8.6 admissions/100 follow-up years, P < 0.001). Cyclosporine, intensive topical treatment (dithranol), retinoids and PUVA therapy lost popularity in recent years. CONCLUSION: The 'journey' of patients with psoriasis towards a biologic is still long and characterized by many different treatments. Shifts towards fewer conventional drugs before biologic initiation and a clear decrease in hospital and day care admissions before vs. after a biologic are seen. Improvement of this journey, especially in young or recently diagnosed patients, can decrease negative influences on patients' lives and reduce societal impact.

Plasma matrix metalloproteinases are associated with incident cardiovascular disease and all-cause mortality in patients with type 1 diabetes: a 12-year follow-up study.

BACKGROUND: Altered regulation of extracellular matrix remodeling by matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMP) may contribute to vascular complications in type 1 diabetes. We investigated associations between plasma MMP-1, -2, -3, -9, -10 and TIMP-1, and cardiovascular events and all-cause mortality in type 1 diabetic patients. METHODS: We prospectively followed 337 type 1 diabetic patients [mean age 41.4 years (9.6), 39% female], 170 with and 167 without diabetic nephropathy, with median follow-up of 12.3 years. Survival analyses were applied to investigate differences in plasma MMP-1, -2, -3, -9, -10, and TIMP-1-levels in patients with and without a cardiovascular event and in those who died vs survivors. All analyses were adjusted for age, sex, duration of diabetes, HbA1c, nephropathy and for other conventional cardiovascular risk factors. RESULTS: After adjustment for potential confounders, higher MMP-2 plasma levels were significantly associated with higher incidence of cardiovascular events [HR 1.49 (95% CI 1.11; 1.99)], and higher plasma levels of MMP-1 [1.38 (1.07; 1.78)], MMP-2 [1.60 (1.19; 2.15)] and MMP-3 [1.39 (1.05; 1.85)] were associated with all-cause mortality. All associations were independent of low-grade inflammation and endothelial dysfunction as estimated by plasma markers. Associations between MMP-2 and cardiovascular events and between MMP-3 and mortality were attenuated after further adjustment for eGFR and changes in eGFR. CONCLUSIONS: Higher levels of MMP-2 are associated with CVD and higher MMP-1, -2 and -3 with all-cause mortality. In addition, associations between MMP-2 and CVD, and MMP-3 and mortality were attenuated after adjustment for eGFR while both MMPs were associated with eGFR decline, indicating a possible mediating role of eGFR.

Long-term effects of metformin on endothelial function in type 2 diabetes: a randomized controlled trial.

OBJECTIVES: We investigated whether metformin can improve endothelial function and decrease inflammatory activity, and thereby decrease the risk of atherothrombotic disease. SUBJECTS AND DESIGN: A randomized, placebo-controlled trial with a follow-up period of 4.3 years set in the outpatient clinics of three nonacademic hospitals (Hoogeveen, Meppel and Coevorden Hospitals, the Netherlands). A total of 390 patients with type 2 diabetes treated with insulin were included. Either metformin 850 mg or placebo (one to three times daily) was added to insulin therapy. Urinary albumin excretion and plasma levels of von Willebrand factor (vWf), soluble vascular adhesion molecule-1 (sVCAM-1), soluble E-selectin (sE-selectin), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), C-reactive protein (CRP) and soluble intercellular adhesion molecule-1 (sICAM-1) were measured at baseline and after 4, 17, 30, 43 and 52 months. RESULTS: Metformin significantly reduced levels of vWF, sVCAM-1, t-PA, PAI-1, CRP and sICAM-1, which, except for CRP, remained significant after adjustment for baseline differences in age, sex, smoking and severity of previous cardiovascular (CV) disease. No effects on urinary albumin excretion or sE-selectin were observed. The improvements in vWf and sVCAM-1 statistically explained about 34% of the reduction in the risk of CV morbidity and mortality associated with metformin treatment in this study. CONCLUSIONS: Metformin is associated with improvement in some (vWF and sVCAM-1) but not all markers of endothelial function, which may explain why it is associated with a decreased risk of CV disease in type 2 diabetes.

Endothelial dysfunction is associated with a greater depressive symptom score in a general elderly population: the Hoorn Study.

BACKGROUND: Endothelial dysfunction (ED), low-grade inflammation (LGI) and oxidative stress (OxS) may be involved in the pathobiology of depression. Previous studies on the association of these processes in depression have yielded contradictory results. We therefore investigated comprehensively, in a population-based cohort study, the association between ED, LGI and OxS on the one hand and depressive symptoms on the other. METHOD: We used data from the Hoorn Study and determined biomarkers of ED [flow-mediated dilatation (FMD), von Willebrand factor, soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1, soluble thrombomodulin and soluble endothelial selectin], LGI [C-reactive protein, tumour necrosis factor-α, interleukin 6, interleukin 8, serum amyloid A, myeloperoxidase (MPO) and sICAM-1] and OxS (oxidized low density lipoprotein and MPO). Depressive symptoms were quantified by the Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire (n = 493; age 68 years; 49.9% female). Regression analyses were performed with the use of biomarker Z scores. Adjustments were made for age, sex and glucose metabolism status (cohort stratification variables) and prior cardiovascular disease, hypertension, waist-to-hip ratio, cholesterol levels, education level, physical activity, dietary habits, and the use of antihypertensive and/or lipid-lowering medication and/or metformin (potential confounders). RESULTS: After adjustment for age, sex and glucose metabolism status, one standard deviation increase in the ED Z score was associated with a 1.9 [95% confidence interval (CI) 0.7-3.1] higher CES-D score. Additional adjustments did not materially change this result. LGI and OxS were not associated with the CES-D score. CONCLUSIONS: ED, as quantified by an array of circulating biomarkers and FMD, was independently associated with depressive symptoms. This study supports the hypothesis that ED plays an important role in the pathobiology of depression.

The methylglyoxal-derived AGE tetrahydropyrimidine is increased in plasma of individuals with type 1 diabetes mellitus and in atherosclerotic lesions and is associated with sVCAM-1.

AIMS/HYPOTHESIS: Methylglyoxal (MGO) is a major precursor for advanced glycation end-products (AGEs), which are thought to play a role in vascular complications in diabetes. Known MGO-arginine-derived AGEs are 5-hydro-5-methylimidazolone (MG-H1), argpyrimidine and tetrahydropyrimidine (THP). We studied THP in relation to type 1 diabetes, endothelial dysfunction, low-grade inflammation, vascular complications and atherosclerosis. METHODS: We raised and characterised a monoclonal antibody against MGO-derived THP. We measured plasma THP with a competitive ELISA in two cohort studies: study A (198 individuals with type 1 diabetes and 197 controls); study B (individuals with type 1 diabetes, 175 with normoalbuminuria and 198 with macroalbuminuria [>300 mg/24 h]). We measured plasma markers of endothelial dysfunction and low-grade inflammation, and evaluated the presence of THP and N (ε)-(carboxymethyl)lysine (CML) in atherosclerotic arteries. RESULTS: THP was higher in individuals with type 1 diabetes than in those without (median [interquartile range] 115.5 U/µl [102.4-133.2] and 109.8 U/µl [91.8-122.3], respectively; p = 0.03). THP was associated with plasma soluble vascular cell adhesion molecule 1 in both study A (standardised ß = 0.48 [95% CI 0.38, 0.58]; p < 0.001) and study B (standardised ß = 0.31 [95% CI 0.23, 0.40]; p < 0.001), and with secreted phospholipase A2 (standardised ß = 0.26 [95% CI 0.17, 0.36]; p < 0.001) in study B. We found no association of THP with micro- or macro-vascular complications. Both THP and CML were detected in atherosclerotic arteries. CONCLUSIONS/INTERPRETATION: Our results suggest that MGO-derived THP may reflect endothelial dysfunction among individuals with and without type 1 diabetes, and therefore may potentially play a role in the development of atherosclerosis and vascular disease.

Current therapeutic interventions in the glycation pathway: evidence from clinical studies.

The increased formation of advanced glycation endproducts (AGEs) constitutes a potential mechanism of hyperglycaemia-induced micro- and macrovascular disease in diabetes. In vitro and animal experiments have shown that various interventions can inhibit formation and/or actions of AGEs, in particular the specific AGE inhibitor aminoguanidine and the AGEs crosslink breaker alagebrium, and the B vitamins pyridoxamine and thiamine, and the latter's synthetic derivative, benfotiamine. The potential clinical value of these interventions, however, remains to be established. The present review provides, from the clinical point of view, an overview of current evidence on interventions in the glycation pathway relating to (i) the clinical benefits of specific AGE inhibitors and AGE breakers and (ii) the potential AGE-inhibiting effects of therapies developed for purposes unrelated to the glycation pathway. We found that safety and/or efficacy in clinical studies with the specific AGE inhibitor, aminoguanidine and the AGE breaker, alagebrium, appeared to be a concern. The clinical evidence on the potential AGE-inhibiting effects of B vitamins is still limited. Finally, current evidence for AGE inhibition by therapies developed for purposes unrelated to glycation is limited due to a large heterogeneity in study designs and/or measurement techniques, which have often been sub-optimal. We conclude that, clinical evidence on interventions to inhibit formation and/or action of AGEs is currently weak and unconvincing.

Unhealthy dietary patterns associated with inflammation and endothelial dysfunction in type 1 diabetes: the EURODIAB study.

BACKGROUND AND AIMS: A healthy diet has been inversely associated with endothelial dysfunction (ED) and low-grade inflammation (LGI). We investigated the association between nutrient consumption and biomarkers of ED and LGI in type 1 diabetes. METHODS AND RESULTS: We investigated 491 individuals. Nutrient consumption and lifestyle risk factors were measured in 1989 and 1997. Biomarkers of ED (von Willebrand factor, soluble vascular cell adhesion molecule-1 and soluble endothelial selectin) and LGI (C-reactive protein, interleukin 6 and tumour necrosis factor α) were measured in 1997 and averaged into Z-scores. The nutrient residual method was used to adjust individual nutrient intake for energy intake. Data were analysed with generalised estimation equations. We report increments/decrements in nutrient consumption, averaged over time, per +1 standard deviation (SD) of 1997 ED or LGI Z-scores, after adjustment for sex, age, duration of diabetes, investigation centre, body mass index, energy intake, smoking behaviour, alcohol consumption, and each of the other nutrients. One SD elevation in ED Z-score was associated with a diet lower in fibre [ß(95%CI);-0.09(-0.18;-0.004)], polyunsaturated fat [-0.18(-0.31;-0.05)] and vegetable protein [-0.10(-0.20;-0.001)]. For the LGI Z-score results showed associations with fibre [-0.09(-0.17;-0.01)], polyunsaturated fat [-0.14(-0.24;-0.03)] and cholesterol [0.10(0.01; 0.18)]. CONCLUSION: In type 1 diabetes, consumption of less fibre, polyunsaturated fat and vegetable protein, and more cholesterol over the study period was associated with more ED and LGI. Following dietary guidelines in type 1 diabetes may reduce cardiovascular disease risk by favourably affecting ED and LGI.

Serum levels of autoantibodies against the angiotensin II type I receptor are not associated with serum dicarbonyl or AGE levels in patients with an aldosterone-producing adenoma.

Patients with an aldosterone-producing adenoma (APA) carry a higher risk of cardiovascular disease and commonly have high levels of autoantibodies (AT1AA) that may activate the angiotensin II type 1 receptor (AT1R). AT1R activation is linked to an increase of the glucose metabolite methylglyoxal (MGO), a potential precursor of advanced glycation endproducts (AGEs) and driver of vascular inflammation. We investigated whether serum AT1AA levels are associated with serum MGO and AGE levels in APA patients. In a case series of 26 patients with APA we measured levels of dicarbonyls MGO, glyoxal (GO) and 3-deoxyglucosone (3-DG), and dicarbonyl-derived AGEs 5-hydro-5-methylimidazolone (MG-H1), Nε-(carboxyethyl)lysine (CEL) and Nε-(carboxymethyl)lysine (CML) with UPLC-MS/MS. We also measured AT1AA by ELISA. These measurements were repeated 1-month after adrenalectomy in a subset of 14 patients. Panels of inflammation and endothelial function were also measured by immunoassays. Although baseline higher AT1AA levels tended to be correlated with higher baseline serum MGO, GO and 3-DG levels (r = 0.18, p = 0.38; r = 0.20, p = 0.33; r = 0.23, p = 0.26; respectively), these correlations were not statistically significant. We observed no obvious correlations between higher AT1AA levels and protein-bound and free MG-H1, CEL and CML levels, and markers of inflammation and endothelial function. No decrease was observed in any of the dicarbonyls, protein-bound AGE levels and markers of inflammation and endothelial function after adrenalectomy. In patients with APA the serum levels of AT1AA were not significantly correlated with serum dicarbonyls, protein-bound and free AGE levels. Increased signalling of the AT1AA receptor may therefore be unlikely to overtly increase systemic dicarbonyl levels.

Protection against methylglyoxal-derived AGEs by regulation of glyoxalase 1 prevents retinal neuroglial and vasodegenerative pathology.

AIMS/HYPOTHESIS: Methylglyoxal (MG) is an important precursor for AGEs. Normally, MG is detoxified by the glyoxalase (GLO) enzyme system (including component enzymes GLO1 and GLO2). Enhanced glycolytic metabolism in many cells during diabetes may overpower detoxification capacity and lead to AGE-related pathology. Using a transgenic rat model that overexpresses GLO1, we investigated if this enzyme can inhibit retinal AGE formation and prevent key lesions of diabetic retinopathy. METHODS: Transgenic rats were developed by overexpression of full length GLO1. Diabetes was induced in wild-type (WT) and GLO1 rats and the animals were killed after 12 or 24 weeks of hyperglycaemia. N ε)-(Carboxyethyl)lysine (CEL), N(ε)-(carboxymethyl)lysine (CML) and MG-derived-hydroimidazalone-1 (MG-H1) were determined by immunohistochemistry and by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MSMS). Müller glia dysfunction was determined by glial fibrillary acidic protein (GFAP) immunoreactivity and by spatial localisation of the potassium channel Kir4.1. Acellular capillaries were quantified in retinal flat mounts. RESULTS: GLO1 overexpression prevented CEL and MG-H1 accumulation in the diabetic retina when compared with WT diabetic counterparts (p < 0.01). Diabetes-related increases in Müller glial GFAP levels and loss of Kir4.1 at the vascular end-feet were significantly prevented by GLO1 overexpression (p < 0.05) at both 12- and 24-week time points. GLO1 diabetic animals showed fewer acellular capillaries than WT diabetic animals (p < 0.001) at 24 weeks' diabetes. CONCLUSIONS/INTERPRETATION: Detoxification of MG reduces AGE adduct accumulation, which, in turn, can prevent formation of key retinal neuroglial and vascular lesions as diabetes progresses. MG-derived AGEs play an important role in diabetic retinopathy.

Higher plasma high-mobility group box 1 levels are associated with incident cardiovascular disease and all-cause mortality in type 1 diabetes: a 12 year follow-up study.

AIMS/HYPOTHESIS: This study aimed to investigate the associations of plasma levels of the pro-inflammatory cytokine high-mobility group box 1 (HMGB1) with incident cardiovascular disease (CVD) and all-cause mortality in patients with type 1 diabetes. METHODS: We prospectively followed 165 individuals with diabetic nephropathy and 168 individuals with persistent normoalbuminuria who were free of CVD at study entry and in whom levels of HMGB1 and other cardiovascular risk factors were measured at baseline. RESULTS: During the course of follow-up (median, 12.3 years [interquartile range, 7.8-12.5]), 80 patients died, 82 suffered a fatal (n = 46) and/or non-fatal (n = 53) CVD event. After adjustment for age, sex, case-control status and other risk factors, patients with higher levels of log(e) HMGB1 had a higher incidence of fatal and non-fatal CVD and all-cause mortality: HR 1.55 (95% CI 0.94, 2.48) and HR 1.86 (95% CI 1.18, 2.93), respectively. Further adjustments for differences in markers of low-grade inflammation, endothelial and renal dysfunction and arterial stiffness did not attenuate these associations because plasma levels of HMGB1 were not independently associated with these variables. CONCLUSIONS/INTERPRETATION: In patients with type 1 diabetes, higher levels of plasma HMGB1 are independently associated with a higher risk of all-cause mortality and, to a lesser extent, with a higher incidence of CVD. Larger studies are needed to ascertain more definitely the role of HMGB1 in the development of vascular complications in diabetes.

Effects of rosuvastatin and atorvastatin on glycaemic control in Type 2 diabetes---the CORALL study.

AIMS: To examine whether high-dose statin therapy in Dutch European patients with Type 2 diabetes and dyslipidaemia influenced variables of glycaemic control. METHODS: The CORALL study, which was a 24-week, open-label, randomized, parallel-group, phase IIIb, multi-centre study, was designed to compare the cholesterol-lowering effects of rosuvastatin compared with atorvastatin in patients with Type 2 diabetes. Fasting plasma glucose levels and HbA(1c) levels were collected at baseline and at 6 and 18 weeks. RESULTS: Treatment with the highest dose of statins, i.e. atorvastatin 80 mg and rosuvastatin 40 mg at 18 weeks from baseline, was associated with increase in HbA(1c) levels; baseline 57 ± 11 mmol/l (7.4 ± 1.0%) to 61 ± 14 mmol/mol (7.7 ± 1.3%) (range 5.0-11.9) for atorvastatin (P = 0.003) and from baseline 60 ± 11 mmol/mol (7.6 ± 1.0%) to 63 ± 13 mmol/mol (7.9 ± 1.2%) (range 5.7-12.3) for rosuvastatin (P < 0.001). Mean fasting plasma glucose increased from baseline 8.7 ± 2.4 mmol/l to 9.5 ± 3.0 mmol/l upon treatment with atorvastatin 20 mg (P = 0.002) and 9.0 ± 3.0 mmol/l after treatment with 80 mg (not significant compared with baseline). The mean fasting plasma glucose did not change after treatment with rosuvastatin (9.1 ± 2.7 mmol/l at baseline, 8.9 ± 2.7 mmol/l with 10 mg, 9.4 ± 2.9 mmol/l with 40 mg). CONCLUSIONS: Glycaemic control deteriorated in patients with diabetes following high-dose statin therapy. Future controlled studies are needed to verify these findings and, if confirmed, determine whether such changes represent a true decline in glycaemic control. Presently, it appears that, based on the overwhelming prospective trial data available, the preventive effect of statin therapy supersedes that of the slight increase in HbA(1c).

Fasting and post-oral-glucose-load levels of methylglyoxal are associated with microvascular, but not macrovascular, disease in individuals with and without (pre)diabetes: The Maastricht Study.

AIMS: Reactive dicarbonyl compounds, such as methylglyoxal (MGO), rise during an oral glucose tolerance test (OGTT), particularly in (pre)diabetes. Fasting MGO levels are associated with chronic kidney disease (CKD) and cardiovascular disease (CVD) in patients with poorly controlled type 2 diabetes mellitus (T2DM). Yet, whether fasting or post-OGTT plasma MGO levels are associated with vascular disease in people with (pre)diabetes is unknown. METHODS: Subjects with normal glucose metabolism (n=1796; age: 57.9±8.2 years; 43.3% men), prediabetes (n=478; age: 61.6±7.6 years; 54.0% men) and T2DM (n=669; age: 63.0±7.5 years; 67.0% men) from the Maastricht Study underwent OGTTs. Plasma MGO levels were measured at baseline and 2h after OGTT by mass spectrometry. Prior CVD was established via questionnaire. CKD was reflected by estimated glomerular filtration rate (eGFR) and albuminuria; retinopathy was assessed using retinal photographs. Data were analyzed using logistic regression adjusted for gender, age, smoking, systolic blood pressure, total-to-HDL cholesterol ratio, triglycerides, HbA1c, BMI and medication use. Odd ratios (ORs) were expressed per standard deviation of LN-transformed MGO. RESULTS: Fasting and post-OGTT MGO levels were associated with higher ORs for albuminuria ≥30mg/24h [fasting: 1.12 (95% CI: 0.97-1.29); post-OGTT: 1.19 (1.01-1.41)], eGFR<60mL/min/1.73 m2 [fasting: 1.58 (95% CI: 1.38-1.82), post-OGTT: 1.57 (1.34-1.83)] and retinopathy [fasting: 1.59 (95% CI: 1.01-2.53), post-OGTT: 1.38 (0.77-2.48)]. No associations with prior CVD were found. CONCLUSION: Fasting and post-OGTT MGO levels were associated with microvascular disease, but not prior CVD. Thus, therapeutic strategies directed at lowering MGO levels may prevent microvascular disease.