Functional properties of high density lipoproteins (HDL) are increasingly recognized to play a physiological role in atheroprotection. Type 2 diabetes mellitus (T2DM) is characterized by low HDL cholesterol, but the effect of chronic hyperglycemia on the anti-inflammatory capacity of HDL, a metric of HDL function, is unclear. Therefore, the aim of the present study was to establish the impact of T2DM on the HDL anti-inflammatory capacity, taking paraoxonase-1 (PON-1) activity and low grade inflammation into account. The HDL anti-inflammatory capacity, determined as the ability to suppress tumor necrosis factor-α (TNF-α) induced vascular cell adhesion molecule-1 (VCAM-1) mRNA expression in endothelial cells in vitro (higher values indicate lower anti-inflammatory capacity), PON-1 (arylesterase) activity, hs-C-reactive protein (hs-CRP), serum amyloid A (SAA) and TNF-α were compared in 40 subjects with T2DM (no insulin or statin treatment) and 36 non-diabetic subjects. T2DM was associated with impaired HDL anti-inflammatory capacity (3.18 vs 1.05 fold increase in VCAM-1 mRNA expression; P < 0.001), coinciding with decreased HDL cholesterol (P = 0.001), apolipoprotein A-I (P = 0.038) and PON-1 activity (P = 0.023), as well as increased hs-CRP (P = 0.043) and TNF-α (P = 0.005). In all subjects combined, age- and sex-adjusted multivariable linear regression analysis demonstrated that impaired HDL anti-inflammatory capacity was associated with hyperglycemia (β = 0.499, P < 0.001), lower PON-1 activity (β = − 0.192, P = 0.030) and higher hs-CRP (β = 0.220, P = 0.016). The HDL anti-inflammatory capacity is substantially impaired in T2DM, at least partly attributable to the degree of hyperglycemia, decreased PON-1 activity and enhanced low grade chronic inflammation. Decreased anti-inflammatory protection capacity of HDL conceivably contributes to the increased atherosclerosis risk associated with T2DM.

GlycA is a novel nuclear magnetic resonance spectroscopy-measured biomarker of systemic inflammation. We determined whether GlycA is associated with incident cardiovascular disease (CVD) in men and women, examined whether this association with CVD is modified by renal function, and compared this association with high sensitivity C-reactive protein (hsCRP). A prospective cohort study was performed among 4,759 subjects (PREVEND study) without a history of CVD and cancer. Incident CVD was defined as the combined endpoint of cardiovascular morbidity and mortality. Cox regression analyses were used to examine associations of baseline GlycA and hsCRP with CVD. 298 first CVD events occurred during a median follow-up of 8.5 years. After adjustment for clinical and lipid measures the hazard ratio (HR) for CVD risk in the highest GlycA quartile was 1.58 (95% CI, 1.05–2.37, P for trend = 0.004). This association was similar after further adjustment for renal function (estimated glomerular filtration rate and urinary albumin excretion). After additional adjustment for hsCRP, GlycA was still associated with incident CVD (HR: 1.16 per SD change (95% CI, 1.01–1.33), P = 0.04). Similar results were obtained for hsCRP (HR per SD change after adjustment for GlycA: 1.17 (95% CI 1.17 (95% CI, 1.01–3.60), P = 0.04). CVD risk was highest in subjects with simultaneously higher GlycA and hsCRP (fully adjusted HR: 1.79 (95% CI, 1.31–2.46), P<0.001). GlycA is associated with CVD risk in men and women, independent of renal function. The association of GlycA with incident CVD is as strong as that of hsCRP.

Non-alcoholic fatty liver disease (NAFLD) is likely to be associated with elevated plasma branched-chain amino acids (BCAAs) and may precede the development of type 2 diabetes (T2D). We hypothesized that BCAAs may be involved in the pathogenesis of T2D attributable to NAFLD and determined the extent to which plasma BCAAs influence T2D development in NAFLD. We evaluated cross-sectional associations of NAFLD with fasting plasma BCAAs (nuclear magnetic resonance spectroscopy), and prospectively determined the extent to which the influence of NAFLD on incident T2D is attributable to BCAA elevations. In the current study, 5791 Prevention of REnal and Vascular ENd-stage Disease (PREVEND) cohort participants without T2D at baseline were included. Elevated fatty liver index (FLI) ≥60, an algorithm based on triglycerides, gamma-glutamyltransferase, body mass index (BMI) and waist circumference, was used as proxy of NAFLD. Elevated FLI ≥ 60 was present in 1671 (28.9%) participants. Cross-sectionally, BCAAs were positively associated with FLI ≥ 60 (β = 0.208, p < 0.001). During a median follow-up of 7.3 years, 276 participants developed T2D, of which 194 (70.2%) had an FLI ≥ 60 (log-rank test, p < 0.001). Cox regression analyses revealed that both FLI ≥60 (hazard ratio (HR) 3.46, 95% CI 2.45–4.87, p < 0.001) and higher BCAA levels (HR 1.19, 95% CI 1.03–1.37, p = 0.01) were positively associated with incident T2D. Mediation analysis showed that the association of FLI with incident T2D was in part attributable to elevated BCAAs (proportion mediated 19.6%). In conclusion, both elevated FLI and elevated plasma BCAA levels are associated with risk of incident T2D. The association of NAFLD with T2D development seems partly mediated by elevated BCAAs.

Plasma branched-chain amino acid (BCAA) levels, measured on nuclear magnetic resonance (NMR) metabolomics research platforms or by mass spectrometry, have been shown to be associated with type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). We developed a new test for quantification of BCAA on a clinical NMR analyzer and used this test to determine the clinical correlates of BCAA in 2 independent cohorts. The performance of the NMR-based BCAA assay was evaluated. A method comparison study was performed with mass spectrometry (LC-MS/MS). Plasma BCAA were measured in the Insulin Resistance Atherosclerosis Study (IRAS, n = 1209; 376 T2DM subjects) and in a Groningen cohort (n = 123; 67 T2DM subjects). In addition, carotid intima media thickness (cIMT) was measured successfully in 119 subjects from the Groningen cohort. NMR-based BCAA assay results were linear over a range of concentrations. Coefficients of variation for inter- and intra-assay precision ranged from 1.8-6.0, 1.7-5.4, 4.4-9.1, and 8.8-21.3%, for total BCAA, valine, leucine, and isoleucine, respectively. BCAA quantified from the same samples using NMR and LC-MS/MS were highly correlated (R2 = 0.97, 0.95 and 0.90 for valine, leucine and isoleucine). In both cohorts total and individual BCAA were elevated in T2DM (P = 0.01 to ≤0.001). Moreover, cIMT was associated with BCAA independent of age, sex, T2DM and metabolic syndrome (MetS) categorization or alternatively of individual MetS components. BCAA levels, measured by NMR in the clinical laboratory, are elevated in T2DM and may be associated with cIMT, a proxy of subclinical atherosclerosis.

Plasma branched-chain amino acids (BCAAs) are linked to metabolic disease, but their relevance for prediction of type 2 diabetes development is unclear. We determined the association of plasma BCAAs with type 2 diabetes risk in the prevention of renal and vascular end-stage disease (PREVEND) cohort. The BCAAs were measured by means of nuclear magnetic resonance spectroscopy. We evaluated the prospective associations of BCAAs with type 2 diabetes in 6244 subjects. The BCAAs were positively associated with HOMA-IR after multivariable adjustment (p < 0.0001). During median follow-up for 7.5 years, 301 cases of type 2 diabetes were ascertained. The Kaplan-Meier plot demonstrated that patients in the highest BCAA quartile presented a higher risk (p log-rank < 0.001). Cox regression analyses revealed a positive association between BCAA and type 2 diabetes; the hazard ratio (HR) for the highest quartile was 6.15 (95% CI: 4.08, 9.24, p < 0.0001). After adjustment for multiple clinical and laboratory variables, the association remained (HR 2.80 (95% CI: 1.72, 4.53), p < 0.0001). C-statistics, Net reclassification improvement, and −2 log likelihood were better after adding BCAAs to the traditional risk model (p = 0.01 to <0.001). In conclusions, high concentrations of BCAAs associate with insulin resistance and with increased risk of type 2 diabetes. This association is independent of multiple risk factors, HOMA-IR and β cell function.

Purpose: The extent to which smoking is associated with thyroid stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) when taking account of clinical variables including alcohol consumption is unclear. We aimed to determine associations of TSH, FT4, and FT3 levels with current smoking. Methods: A cross-sectional study was performed in 5766 euthyroid participants (Prevention of Renal and Vascular End-Stage Disease cohort). Current smoking was determined by self-report, categorized as never, former, and current (≤20 and >20 cigarettes per day). Smoke exposure was determined by urinary cotinine. Results: Current smoking of ≤20 and >20 cigarettes per day was associated with lower TSH and higher FT3 levels. FT4 levels were higher in subjects smoking <20 cigarettes per day vs. never and former smokers. Current smokers also consumed more alcohol. Multivariable linear regression analyses adjusted for age, sex, anti-TPO autoantibody positivity, alcohol consumption, and other variables demonstrated that lower TSH, higher FT4 and higher FT3 were associated with smoking ≤20 cigarettes per day vs. subjects who never smoked (P < 0.001, P = 0.018, and P < 0.001, respectively) without a further significant incremental effect of smoking >20 cigarettes per day. In agreement, TSH was inversely, whereas FT4 and FT3 levels were positively associated with urinary cotinine (P < 0.001 for each). In contrast, alcohol consumption >30 g per day conferred higher TSH and lower FT3 levels. Conclusions: Cigarette smoking is associated with modestly higher FT4 and FT3, and lower TSH levels, partly opposing effects of alcohol consumption.