Association of Both Short-term and Long-term Glycemic Variability With the Development of Microalbuminuria in the ACCORD Trial

Both long- and short-term glycemic variability have been associated with incident diabetes complications. We evaluated their relative and potential additive effects on incident renal complications in the Action to Control Cardiovascular Risk in Diabetes trial. A marker of short-term glycemic variability, 1,5-anhydroglucitol (1,5-AG), was measured in 4,000 random 12-month postrandomization plasma samples (when hemoglobin A1c [HbA1c] was stable). Visit-to-visit fasting plasma glucose coefficient of variation (CV-FPG) was determined from 4 months postrandomization until the end point of microalbuminuria or macroalbuminuria. Using Cox proportional hazards models, high CV-FPG and low 1,5-AG were independently associated with microalbuminuria after adjusting for clinical risk factors. However, only the CV-FPG association remained after additional adjustment for average HbA1c. Only CV-FPG was a significant risk factor for macroalbuminuria. This post hoc analysis indicates that long-term rather than short-term glycemic variability better predicts the risk of renal disease in type 2 diabetes.

ARTICLE HIGHLIGHTS

The relative and potential additive effects of long- and short-term glycemic variability on the development of diabetic complications are unknown. We aimed to assess the individual and combined relationships of long-term visit-to-visit glycemic variability, measured as the coefficient of variation of fasting plasma glucose, and short-term glucose fluctuation, estimated by the biomarker 1,5-anhydroglucitol, with the development of proteinuria. Both estimates of glycemic variability were independently associated with microalbuminuria, but only long-term glycemic variability remained significant after adjusting for average hemoglobin A1c. Our findings suggest that longer-term visit-to-visit glucose variability improves renal disease prediction in type 2 diabetes.

Association of apolipoproteins C-I and C-II truncations with coronary heart disease and progression of coronary artery calcium: Multi-Ethnic Study of Atherosclerosis

BACKGROUND AND AIMS

Higher truncated-to-native proteoform ratios of apolipoproteins (apo) C-I (C-I'/C-I) and C-II (C-II'/C-II) are associated with less atherogenic lipid profiles. We examined prospective relationships of C-I'/C-II and C-II'/C-II with coronary heart disease (CHD) and coronary artery calcium (CAC).

METHODS

ApoC-I and apoC-II proteoforms were measured by mass spectrometry immunoassay in 5790 MESA baseline plasma samples. CHD events (myocardial infarction, resuscitated cardiac arrest, fatal CHD, n = 434) were evaluated for up to 17 years. CAC was measured 1-4 times over 10 years for incident CAC (if baseline CAC = 0), and changes (follow-up adjusted for baseline) in CAC score and density (if baseline CAC>0).

RESULTS

C-II'/C-II was inversely associated with CHD (n = 434 events) after adjusting for non-lipid cardiovascular risk factors (Hazard ratio: 0.89 [95% CI: 0.81-0.98] per SD), however, the association was attenuated after further adjustment for HDL levels (0.93 [0.83-1.03]). There was no association between C-I'/C-I and CHD (0.98 [0.88-1.08]). C-II'/C-II was positively associated with changes in CAC score (3.4% [95%CI: 0.6, 6.3]) and density (6.3% [0.3, 4.2]), while C-I'/C-I was inversely associated with incident CAC (Risk ratio: 0.89 [95% CI: 0.81, 0.98]) in fully adjusted models that included plasma lipids. Total apoC-I and apoC-II concentrations were not associated with CHD, incident CAC or change in CAC score.

CONCLUSIONS

Increased apoC-II truncation was associated with reduced CHD, possibly explained by differences in lipid metabolism. Increased apoC-I and apoC-II truncations were also associated with less CAC progression and/or development of denser coronary plaques.

Apo CIII Proteoforms, Plasma Lipids, and Cardiovascular Risk in MESA

BACKGROUND

Apo CIII (apolipoprotein CIII) is an important regulator of triglyceride metabolism and was associated with cardiovascular risk in several cohorts. It is present in 4 major proteoforms, a native peptide (CIII0a), and glycosylated proteoforms with zero (CIII0b), 1 (CIII1, most abundant), or 2 (CIII2) sialic acids, which may differentially modify lipoprotein metabolism. We studied the relationships of these proteoforms with plasma lipids and cardiovascular risk.

METHODS

Apo CIII proteoforms were measured by mass spectrometry immunoassay in baseline plasma samples of 5791 participants of Multi-Ethnic Study of Atherosclerosis, an observational community-based cohort. Standard plasma lipids were collected for up to 16 years and cardiovascular events (myocardial infarction, resuscitated cardiac arrest, or stroke) were adjudicated for up to 17 years.

RESULTS

Apo CIII proteoform composition differed by age, sex, race and ethnicity, body mass index, and fasting glucose. Notably, CIII1 was lower in older participants, men and Black and Chinese (versus White) participants, and higher in obesity and diabetes. In contrast, CIII2 was higher in older participants, men, Black, and Chinese persons, and lower in Hispanic individuals and obesity. Higher CIII2 to CIII1 ratio (CIII2/III1) was associated with lower triglycerides and higher HDL (high-density lipoprotein) in cross-sectional and longitudinal models, independently of clinical and demographic risk factors and total apo CIII. The associations of CIII0a/III1 and CIII0b/III1 with plasma lipids were weaker and varied through cross-sectional and longitudinal analyses. Total apo CIII and CIII2/III1 were positively associated with cardiovascular disease risk (n=669 events, hazard ratios, 1.14 [95% CI, 1.04-1.25] and 1.21 [1.11-1.31], respectively); however, the associations were attenuated after adjustment for clinical and demographic characteristics (1.07 [0.98-1.16]; 1.07 [0.97-1.17]). In contrast, CIII0b/III1 was inversely associated with cardiovascular disease risk even after full adjustment including plasma lipids (0.86 [0.79-0.93]).

CONCLUSIONS

Our data indicate differences in clinical and demographic relationships of apo CIII proteoforms, and highlight the importance of apo CIII proteoform composition in predicting future lipid patterns and cardiovascular disease risk.

Plasma proteoforms of apolipoproteins C-I and C-II are associated with plasma lipids in the Multi-Ethnic Study of Atherosclerosis

Apolipoproteins (apo) C-I and C-II are key regulators of triglyceride and HDL metabolism. Both exist as full-size native and truncated (apoC-I'; apoC-II') posttranslational proteoforms. However, the determinants and the role of these proteoforms in lipid metabolism are unknown. Here, we measured apoC-I and apoC-II proteoforms by mass spectrometry immunoassay in baseline and 10-year follow-up plasma samples from the Multi-Ethnic Study of Atherosclerosis. We found that baseline total apoC-I (mean = 9.2 mg/dl) was lower in African Americans (AA), Chinese Americans (CA), and Hispanics (by 1.8; 1.0; 1.0 mg/dl vs. whites), higher in women (by 1.2 mg/dl), and positively associated with plasma triglycerides and HDL. Furthermore, we observed that the truncated-to-native apoC-I ratio (apoC-I'/C-I) was lower in CA, negatively associated with triglycerides, and positively associated with HDL. We determined that total apoC-II (8.8 mg/dl) was lower in AA (by 0.8 mg/dl) and higher in CA and Hispanics (by 0.5 and 0.4 mg/dl), positively associated with triglycerides, and negatively associated with HDL. In addition, apoC-II'/C-II was higher in AA and women, negatively associated with triglycerides, and positively associated with HDL. We showed that the change in triglycerides was positively associated with changes in total apoC-I and apoC-II and negatively associated with changes in apoC-I'/C-I and apoC-II'/C-II, whereas the change in HDL was positively associated with changes in total apoC-I and apoC-II'/C-II and negatively associated with change in total apoC-II. This study documents racial/ethnic variation in apoC-I and apoC-II plasma levels and highlights apolipoprotein posttranslational modification as a potential regulator of plasma lipids.

Advanced Glycation End Products Predict Loss of Renal Function and High-Risk Chronic Kidney Disease in Type 2 Diabetes

OBJECTIVE

To evaluate the association of a multicomponent advanced glycation end product (AGE) panel with decline in kidney function and its utility in predicting renal function loss (RFL) when added to routine clinical measures in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Carboxymethyl and carboxyethyl lysine and methylglyoxal, 3-deoxyglucosone, and glyoxal hydroimidazolones were measured in baseline serum and plasma samples, respectively, from Action to Control Cardiovascular Risk in Diabetes (ACCORD) (n = 1,150) and Veterans Affairs Diabetes Trial (VADT) (n = 447) participants. A composite AGE score was calculated from individual AGE z scores. The primary outcome was a sustained 30% decline in estimated glomerular filtration rate (eGFR) (30% RFL in both cohorts). Secondary outcomes (in ACCORD) were 40% RFL, macroalbuminuria, and high-risk chronic kidney disease (hrCKD).

RESULTS

After adjustment for baseline and follow-up HbA1c and other risk factors in ACCORD, the AGE score was associated with reduction in eGFR (β-estimate -0.66 mL/min ⋅ 1.73 m2 per year; P = 0.001), 30% RFL (hazard ratio 1.42 [95% CI 1.13-1.78]; P = 0.003), 40% RFL (1.40 [1.13-1.74]; P = 0.003), macroalbuminuria (1.53 [1.13-2.06]; P = 0.006), and hrCKD (1.88 [1.37-2.57]; P < 0.0001). AGE score improved net reclassification (NRI) and relative integrated discrimination (IDI) for 30% RFL (NRI 23%; P = 0.02) (relative IDI 7%; P = 0.009). In VADT, the AGE score calculated by the ACCORD-derived coefficients was associated with 30% RFL (1.37 [1.03-1.82); P = 0.03) and improved NRI (24%; P = 0.03) but not IDI (P = 0.18).

CONCLUSIONS

These data provide further support for a causal role of AGEs in diabetic nephropathy independently of glycemic control and suggest utility of the composite AGE panel in predicting long-term decline in renal function.

Refining determinants of associations of visit-to-visit blood pressure variability with cardiovascular risk: results from the Action to Control Cardiovascular Risk in Diabetes Trial

OBJECTIVES

As there is uncertainty about the extent to which baseline blood pressure level or cardiovascular risk modifies the relationship between blood pressure variability (BPv) and cardiovascular disease, we comprehensively examined the role of BPv in cardiovascular disease risk in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Trial.

METHODS

Using data from ACCORD, we examined the relationship of BPv with development of the primary CVD outcome, major coronary heart disease (CHD), and total stroke using time-dependent Cox proportional hazards models.

RESULTS

BPv was associated with the primary CVD outcome and major CHD but not stroke. The positive association with the primary CVD outcome and major CHD was more pronounced in low and high strata of baseline SBP (<120 and >140 mmHg) and DBP (<70 and >80 mmHg). The effect of BPv on CVD and CHD was more pronounced in those with both prior CVD history and low blood pressure. Dips, not elevations, in blood pressure appeared to drive these associations. The relationships were generally not attenuated by adjustment for mean blood pressure, medication adherence, or baseline comorbidities. A sensitivity analysis using CVD events from the long-term posttrial follow-up (ACCORDION) was consistent with the results from ACCORD.

CONCLUSION

In ACCORD, the effect of BPv on adverse cardiovascular (but not cerebrovascular) outcomes is modified by baseline blood pressure and prior CVD. Recognizing these more nuanced relationships may help improve risk stratification and blood pressure management decisions as well as provide insight into potential underlying mechanisms.

The Effect of Exenatide Once Weekly on Carotid Atherosclerosis in Individuals With Type 2 Diabetes: An 18-Month Randomized Placebo-Controlled Study

OBJECTIVE

Glucagon-like peptide 1 receptor agonists (GLP-1RAs) improved multiple proatherogenic risk factors and reduced cardiovascular events in recent clinical trials, suggesting that they may slow progression of atherosclerosis. We tested whether exenatide once weekly reduces carotid plaque progression in individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In a double-blind, pragmatic trial, 163 participants were randomized (2:1) to exenatide (n = 109) or placebo (n = 54). Changes in carotid plaque volume and composition were measured at 9 and 18 months by multicontrast 3 Tesla MRI. Fasting and post-high-fat meal plasma glucose and lipids, and endothelial function responses, were measured at 3, 9, and 18 months.

RESULTS

Exenatide reduced hemoglobin A_1c (HbA_1c) (estimated difference vs. placebo 0.55%, P = 0.0007) and fasting and postmeal plasma glucose (19 mg/dL, P = 0.0002, and 25 mg/dL, P < 0.0001, respectively). Mean (SD) change in plaque volume in the exenatide group (0.3% [2%]) was not different from that in the placebo group (-2.2% [8%]) (P = 0.4). The change in plaque volume in the exenatide group was associated with changes in HbA_1c (r = 0.38, P = 0.0004), body weight, and overall plasma glucose (r = 0.29, P = 0.007 both). There were no differences in changes in plaque composition, body weight, blood pressure, fasting and postmeal plasma triglycerides, and endothelial function between the groups.

CONCLUSIONS

Exenatide once weekly for up to 18 months improved fasting and postprandial glycemic control but did not modify change in carotid plaque volume or composition. This study raises the possibility that short-term antiatherosclerotic effects may not play a central role in the cardiovascular benefits of GLP-1RAs.

Fasting Glucose Variation Predicts Microvascular Risk in ACCORD and VADT

AIMS

The association of glycemic variability with microvascular disease complications in type 2 diabetes (T2D) has been under-studied and remains unclear. We investigated this relationship using both Action to Control Cardiovascular Risk in Diabetes (ACCORD) and the Veteran Affairs Diabetes Trial (VADT).

METHODS

In ACCORD, fasting plasma glucose (FPG) was measured 1 to 3 times/year for up to 84 months in 10 251 individuals. In the VADT, FPG was measured every 3 months for up to 87 months in 1791 individuals. Variability measures included coefficient of variation (CV) and average real variability (ARV) for fasting glucose. The primary composite outcome was time to either severe nephropathy or retinopathy event and secondary outcomes included each outcome individually. To assess the association, we considered variability measures as time-dependent covariates in Cox proportional hazard models. We conducted a meta-analysis across the 2 trials to estimate the risk of fasting glucose variability as well as to assess the heterogenous effects of FPG variability across treatment arms.

RESULTS

In both ACCORD and the VADT, the CV and ARV of FPG were associated with development of future microvascular outcomes even after adjusting for other risk factors, including measures of average glycemic control (ie, cumulative average of HbA1c). Meta-analyses of these 2 trials confirmed these findings and indicated FPG variation may be more harmful in those with less intensive glucose control.

CONCLUSIONS

This post hoc analysis indicates that variability of FPG plays a role in, and/or is an independent and readily available marker of, development of microvascular complications in T2D.

Blood Pressure Variability and Risk of Heart Failure in ACCORD and the VADT

OBJECTIVE

Although blood pressure variability is increasingly appreciated as a risk factor for cardiovascular disease, its relationship with heart failure (HF) is less clear. We examined the relationship between blood pressure variability and risk of HF in two cohorts of type 2 diabetes participating in trials of glucose and/or other risk factor management.

RESEARCH DESIGN AND METHODS

Data were drawn from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial and the Veterans Affairs Diabetes Trial (VADT). Coefficient of variation (CV) and average real variability (ARV) were calculated for systolic (SBP) and diastolic blood pressure (DBP) along with maximum and cumulative mean SBP and DBP during both trials.

RESULTS

In ACCORD, CV and ARV of SBP and DBP were associated with increased risk of HF, even after adjusting for other risk factors and mean blood pressure (e.g., CV-SBP: hazard ratio [HR] 1.15, P = 0.01; CV-DBP: HR 1.18, P = 0.003). In the VADT, DBP variability was associated with increased risk of HF (ARV-DBP: HR 1.16, P = 0.001; CV-DBP: HR 1.09, P = 0.04). Further, in ACCORD, those with progressively lower baseline blood pressure demonstrated a stepwise increase in risk of HF with higher CV-SBP, ARV-SBP, and CV-DBP. Effects of blood pressure variability were related to dips, not elevations, in blood pressure.

CONCLUSIONS

Blood pressure variability is associated with HF risk in individuals with type 2 diabetes, possibly a consequence of periods of ischemia during diastole. These results may have implications for optimizing blood pressure treatment strategies in those with type 2 diabetes.

Effects of saxagliptin on adipose tissue inflammation and vascular function in overweight and obese people: a placebo-controlled study

AIMS

To test the effect of the dipeptidyl peptidase-4 inhibitor saxagliptin on adipose tissue inflammation and microvascular function, and whole-body postprandial endothelial function.

METHODS

A randomized, double-blind, placebo-controlled, parallel study was conducted between June 2013 and November 2016 in 44 overweight or obese people without diabetes (saxagliptin, n=28; placebo, n=16). Subcutaneous abdominal adipose tissue biopsies, a 4-h fat-enriched meal test and peripheral arterial tonometry for measurement of endothelial function were performed at baseline and after 6 weeks of treatment with saxagliptin (5 mg/day) or matching placebo.

RESULTS

Forty participants were analysed (saxagliptin, n=26; placebo, n=14). Secretion of interleukin-8 from adipose tissue explants was reduced after saxagliptin (median fold-change from baseline: 0.8 saxagliptin vs 3.3 placebo; P=0.02). Adipose tissue expression of thioredoxin-inhibitory protein (TxNIP) was lower after saxagliptin (0.75 vs 1.0; P=0.02), while there were no significant differences in adipose tissue secretion of interleukin-1b, interleukin-6 or macrophage chemoattractant protein 1 (MCP-1), adipose tissue macrophage content, adipose tissue mRNA levels of mcp1, cd36, cd68, il6, il8, txnip and adpq, and activation of adipose tissue inflammatory pathways [extracellular signal-regulated kinase, c-Jun N-terminal kinase (JNK) and nuclear factor-κB (NF- κB)] or insulin-induced vasodilation of adipose tissue arterioles. Postprandial plasma glucose was slightly lower (by an estimated 0.3 mmol/l; P=0.01), while postprandial insulin, triglyceride levels and endothelial function were unchanged after saxagliptin.

CONCLUSIONS

The effect of saxagliptin on adipose tissue inflammation was relatively modest, with many inflammatory markers unchanged. We also found no evidence that saxagliptin therapy improved adipose tissue arteriole vasodilation or postprandial endothelial function.

Glycaemic variation is a predictor of all-cause mortality in the Veteran Affairs Diabetes Trial

Diabetes is associated with substantially increased mortality. Classic risk factors explain a portion of the excess of mortality in type 2 diabetes. The aim of this study was to examine whether visit-to-visit variation in fasting glucose and haemoglobin A1c values in the Veteran Affairs Diabetes Trial were associated with all-cause mortality in patients with type 2 diabetes in addition to other comorbidity conditions, hypoglycaemic events and adverse lifestyle behaviours. The Veteran Affairs Diabetes Trial was a randomized trial that enrolled 1791 military veterans who had a suboptimal response to therapy for type 2 diabetes to receive either intensive or standard glucose control. During the Veteran Affairs Diabetes Trial, fasting glucose and haemoglobin A1c were measured quarterly for up to 84 months. Variability measures included coefficient of variation and average real variability. We found that variability measures (coefficient of variation and average real variability) of fasting glucose were predictors of all-cause mortality, even after adjusting for comorbidity index, mean fasting glucose and adverse lifestyle behaviour during the study. Accounting for severe hypoglycaemia did not weaken this association. Our analysis indicates that in the Veteran Affairs Diabetes Trial, longitudinal variation in fasting glucose was associated with all-cause mortality, even when accounting for standard measures of glucose control as well as comorbidity and lifestyle factors.

Advanced Glycation End Products, Oxidation Products, and Incident Cardiovascular Events in Patients With Type 2 Diabetes

OBJECTIVE

The goal of this study was to determine whether plasma levels of advanced glycation end products (AGE) and oxidation products (OP) predict the incidence of cardiovascular disease (CVD) in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Five specific AGE (methylglyoxal hydroimidazolone, carboxymethyl lysine, carboxyethyl lysine, 3-deoxyglucosone hydroimidazolone, and glyoxal hydroimidazolone) and two OP (2-aminoadipic acid and methionine sulfoxide [MetSO]) were measured at baseline in two intensive glucose-lowering studies: 1) a subcohort of the Veterans Affairs Diabetes Trial (VADT) (n = 445) and 2) a nested case-control subgroup from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study (n = 271).

RESULTS

Increased levels of several AGE and OP were associated with older age, decreased kidney function, previous CVD, and longer diabetes duration, but not with hemoglobin A_1c. In the VADT, increased risk of incident CVD events (n = 107) was associated with lower MetSO after adjusting for age, race/ethnicity, sex, prior CVD event, kidney function, treatment assignment, and diabetes duration (hazard ratio [HR] 0.53; 95% CI 0.28-0.99; P = 0.047). Individuals with both low MetSO and high 3-deoxyglucosone hydroimidazolone concentrations were at highest risk for CVD (HR 1.70; P = 0.01). In the ACCORD study, those with incident CVD events (n = 136) had lower MetSO (by 14%; P = 0.007) and higher glyoxal hydroimidazolone and carboxymethyl lysine (by 18% and 15%, respectively; P = 0.04 for both); however, only the difference in MetSO remained significant after adjustment for prior CVD event (P = 0.002).

CONCLUSIONS

Lower levels of MetSO and higher levels of select AGE are associated with increased incident CVD and may help account for the limited benefit of intensive glucose lowering in type 2 diabetes.

Effect of liraglutide on dietary lipid-induced insulin resistance in humans

AIMS

To test whether liraglutide suppresses postprandial elevations in lipids and thus protects against high saturated fatty acid (SFA) diet-induced insulin resistance.

METHODS

In a randomized placebo-controlled crossover study, 32 participants with normal or mildly impaired glucose tolerance received liraglutide and placebo for 3 weeks each. Insulin suppression tests (IST) were conducted at baseline and after a 24-hour SFA-enriched diet after each treatment. Plasma glucose, insulin, triglycerides and non-esterified fatty acids (NEFA) were measured over the initial 8 hours (breakfast and lunch) on the SFA diet. A subset of participants underwent ex vivo measurements of insulin-mediated vasodilation of adipose tissue arterioles and glucose metabolism regulatory proteins in skeletal muscle.

RESULTS

Liraglutide reduced plasma glucose, triglycerides and NEFA concentrations during the SFA diet (by 50%, 25% and 9%, respectively), and the SFA diet increased plasma glucose during the IST (by 36%; all P < .01 vs placebo). The SFA diet-induced impairment of vasodilation on placebo (-9.4% vs baseline; P < .01) was ameliorated by liraglutide (-4.8%; P = .1 vs baseline). In skeletal muscle, liraglutide abolished the SFA-induced increase in thioredoxin-interacting protein (TxNIP) expression (75% decrease; P < .01 vs placebo) and increased 5'AMP-activated protein kinase (AMPK) phosphorylation (50% vs -3%; P = .04 vs placebo).

CONCLUSIONS

Liraglutide blunted the SFA-enriched diet-induced peripheral insulin resistance. This effect may be related to improved microvascular function and modulation of TxNIP and AMPK pathways in skeletal muscle.

Association of Cystatin C Proteoforms with Estimated Glomerular Filtration Rate

Background

Cystatin C (CysC), a marker for chronic kidney disease, exists as three sequence proteoforms, in addition to the wild-type sequence: one contains hydroxyproline at position 3 (3Pro-OH), the two others have truncated sequences (des-S and des-SSP). Here, we examine correlations between each of these CysC proteoforms and estimated glomerular filtration rate (eGFR), a diagnostic criterion for chronic kidney disease (CKD).

Methods

CysC proteoform concentrations were determined from the plasma of 297 diabetes patients at a baseline time point and nine-months later, using a mass spectrometric immunoassay, and were correlated with eGFR calculations.

Results

In all samples, 3Pro-OH was the most abundant CysC proteoform, followed by the wild-type proteoform. Least abundant were the truncated CysC proteoforms, des-S and des-SSP, although they demonstrated stronger negative correlation with eGFR than the 3Pro-OH and wild-type proteoforms. The des-SSP truncated proteoform exhibited negative predictive value for eGFR.

Conclusions

The truncated CysC proteoforms show potential for clinical and prognostic utility in CKD staging. This could be useful in populations where current methods do not provide satisfactory solutions.

A human model of dietary saturated fatty acid induced insulin resistance

BACKGROUND

Increased consumption of high-fat diets is associated with the development of insulin resistance and type 2 diabetes. Current models to study the mechanisms of high-fat diet-induced IR in humans are limited by their long duration or low efficacy. In the present study we developed and characterized an acute dietary model of saturated fatty acid-enriched diet induced insulin resistance.

METHODS

High caloric diets enriched with saturated fatty acids (SFA) or carbohydrates (CARB) were evaluated in subjects with normal and impaired glucose tolerance (NGT or IGT). Both diets were compared to a standard eucaloric American Heart Association (AHA) control diet in a series of crossover studies. Whole body insulin resistance was estimated as steady state plasma glucose (SSPG) concentrations during the last 30min of a 3-h insulin suppression test.

RESULTS

SSPG was increased after a 24-h SFA diet (by 83±74% vs. control, n=38) in the entire cohort, which was comprised of participants with NGT (92±82%, n=22) or IGT (65±55%, n=16) (all p<0.001). SSPG was also increased after a single SFA breakfast (55±32%, p=0.008, n=7). The increase in SSPG was less pronounced after an overnight fast following a daylong SFA diet (24±31%, p=0.04, n=10), and further attenuated 24h after returning to the control diet (19±35%, p=0.09, n=11). SSPG was not increased after a 24-h CARB diet (26±50%, p=0.11, n=12).

CONCLUSIONS

A short-term SFA-enriched diet induced whole body insulin resistance in both NGT and IGT subjects. Insulin resistance persisted overnight after the last SFA meal and was attenuated by one day of a healthy diet. This model offers opportunities for identifying early mechanisms and potential treatments of dietary saturated fat induced insulin resistance.

The association of plasma cystatin C proteoforms with diabetic chronic kidney disease

Background

Cystatin C (CysC) is an endogenous cysteine protease inhibitor that can be used to assess the progression of kidney function. Recent studies demonstrate that CysC is a more specific indicator of glomerular filtration rate (GFR) than creatinine. CysC in plasma exists in multiple proteoforms. The goal of this study was to clarify the association of native CysC, CysC missing N-terminal Serine (CysC des-S), and CysC without three N-terminal residues (CysC des-SSP) with diabetic chronic kidney disease (CKD).

Results

Using mass spectrometric immunoassay, the plasma concentrations of native CysC and the two CysC truncation proteoforms were examined in 111 individuals from three groups: 33 non-diabetic controls, 34 participants with type 2 diabetes (DM) and without CKD and 44 participants with diabetic CKD. Native CysC concentrations were 1.4 fold greater in CKD compared to DM group (p = 0.02) and 1.5 fold greater in CKD compared to the control group (p = 0.001). CysC des-S concentrations were 1.55 fold greater in CKD compared to the DM group (p = 0.002) and 1.9 fold greater in CKD compared to the control group (p = 0.0002). CysC des-SSP concentrations were 1.8 fold greater in CKD compared to the DM group (p = 0.008) and 1.52 fold greater in CKD compared to the control group (p = 0.002). In addition, the concentrations of CysC proteoforms were greater in the setting of albuminuria. The truncated CysC proteoform concentrations were associated with estimated GFR independent of native CysC concentrations.

Conclusion

Our findings demonstrate a greater amount of CysC proteoforms in diabetic CKD. We therefore suggest assessing the role of cystatin C proteoforms in the progression of CKD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12953-016-0096-7) contains supplementary material, which is available to authorized users.

Posttranslational modifications of apolipoprotein A-II proteoforms in type 2 diabetes

BACKGROUND

Apolipoprotein A-II (apoA-II) is the second most abundant protein in high-density lipoprotein particles. However, it exists in plasma in multiple forms. The effect of diabetes on apoA-II proteoforms is not known.

OBJECTIVE

Our objective was to characterize plasma apoA-II proteoforms in participants with and without type 2 diabetes.

METHODS

Using a novel mass spectrometric immunoassay, the relative abundance of apoA-II proteoforms was examined in plasma of 30 participants with type 2 diabetes and 25 participants without diabetes.

RESULTS

Six apoA-II proteoforms (monomer, truncated TQ monomer, truncated Q monomer, dimer, truncated Q dimer, and truncated 2Qs dimer) and their oxidized proteoforms were identified. The ratios of oxidized monomer and all oxidized proteoforms to the native apoA-II were significantly greater in the diabetic group (P = .004 and P = .005, respectively) compared with the nondiabetic group.

CONCLUSION

The relative abundance of oxidized apoA-II is significantly increased in type 2 diabetes.

Disialylated apolipoprotein C-III proteoform is associated with improved lipids in prediabetes and type 2 diabetes

The apoC-III proteoform containing two sialic acid residues (apoC-III2) has different in vitro effects on lipid metabolism compared with asialylated (apoC-III0) or the most abundant monosialylated (apoC-III1) proteoforms. Cross-sectional and longitudinal associations between plasma apoC-III proteoforms (by mass spectrometric immunoassay) and plasma lipids were tested in two randomized clinical trials: ACT NOW, a study of pioglitazone in subjects with impaired glucose tolerance (n = 531), and RACED (n = 296), a study of intensive glycemic control and atherosclerosis in type 2 diabetes patients. At baseline, higher relative apoC-III2 and apoC-III2/apoC-III1 ratios were associated with lower triglycerides and total cholesterol in both cohorts, and with lower small dense LDL in the RACED. Longitudinally, changes in apoC-III2/apoC-III1 were inversely associated with changes in triglycerides in both cohorts, and with total and small dense LDL in the RACED. apoC-III2/apoC-III1 was also higher in patients treated with PPAR-γ agonists and was associated with reduced cardiovascular events in the RACED control group. Ex vivo studies of apoC-III complexes with higher apoC-III2/apoC-III1 showed attenuated inhibition of VLDL uptake by HepG2 cells and LPL-mediated lipolysis, providing possible functional explanations for the inverse association between a higher apoC-III2/apoC-III1 and hypertriglyceridemia, proatherogenic plasma lipid profiles, and cardiovascular risk.

Exenatide Protects Against Glucose- and Lipid-Induced Endothelial Dysfunction: Evidence for Direct Vasodilation Effect of GLP-1 Receptor Agonists in Humans

GLP-1 receptor (GLP-1R) agonists may improve endothelial function (EF) via metabolic improvement and direct vascular action. The current study determined the effect of GLP-1R agonist exenatide on postprandial EF in type 2 diabetes and the mechanisms underlying GLP-1R agonist-mediated vasodilation. Two crossover studies were conducted: 36 participants with type 2 diabetes received subcutaneous exenatide or placebo for 11 days and EF, and glucose and lipid responses to breakfast and lunch were determined; and 32 participants with impaired glucose tolerance (IGT) or diet-controlled type 2 diabetes had EF measured before and after intravenous exenatide, with or without the GLP-1R antagonist exendin-9. Mechanisms of GLP-1R agonist action were studied ex vivo on human subcutaneous adipose tissue arterioles and endothelial cells. Subcutaneous exenatide increased postprandial EF independent of reductions in plasma glucose and triglycerides. Intravenous exenatide increased fasting EF, and exendin-9 abolished this effect. Exenatide elicited eNOS activation and NO production in endothelial cells, and induced dose-dependent vasorelaxation and reduced high-glucose or lipid-induced endothelial dysfunction in arterioles ex vivo. These effects were reduced with AMPK inhibition. In conclusion, exenatide augmented postprandial EF in subjects with diabetes and prevented high-glucose and lipid-induced endothelial dysfunction in human arterioles. These effects were largely direct, via GLP-1R and AMPK activation.

Salsalate has no effect on insulin secretion but decreases insulin clearance: a randomized, placebo-controlled trial in subjects without diabetes

To elucidate whether increased insulin concentration after salsalate treatment (3 g/day for 7 days) is attributable to an increased insulin secretion rate (ISR) or to reduced metabolic clearance of endogenous insulin (MCI) during stepped glucose infusion (SGI). The analysis was performed in obese subjects who participated in a randomized double-blind, parallel, placebo-controlled clinical trial. A total of 27 participants (16 on salsalate, 11 on placebo) completed baseline and follow-up SGI. During SGI in the salsalate group, C-peptide concentrations were reduced by 11%, while plasma insulin concentrations were increased by 30%, corresponding to a 30% reduction in MCI (p < 0.0001). At molar increments of glucose, insulin concentrations were increased by 27% (p = 0.02), but ISR was unchanged. Salsalate did not alter insulin secretion, but lowered MCI, indicating that a reduction in insulin clearance is the principal mechanism for increased insulin levels after salsalate administration.

Abstract 30: Apolipoprotein CIII Sialylation is a Critical Determinant of Liver Triglyceride Metabolism

Apolipoprotein (apo) CIII inhibits lipoprotein lipase (LPL) activity and remnant particle uptake in the liver by the lipolysis stimulated receptor (LSR); and therefore modulates liver and systemic lipid metabolism. Although post-translational modifications of apo CIII lead to asialylated, mono- or di-sialylated variants, the biological relevance of these sialylations is not known. Our objectives were to determine the association of apo C-III sialylation with plasma triglycerides and liver fat content in vivo, and to evaluate the effect of apo CIII sialylation on lipid uptake in liver cells or LPL activity in vitro. In 209 obese non-diabetic adolescent Hispanic participants, apo CIII variants in plasma were measured using mass spectrometric immunoassay. Increased plasma apo C-III sialylation (di- to mono-sialylated apo CIII ratio) was associated with lower triglyceride levels (r=-0.43, p<0.001) and liver fat (by MRI, r=-0.27, p<0.001) independent of total apo CIII concentrations. Higher plasma concentrations of the mono-, but not the di-sialylated variant, were associated with higher triglycerides concentrations (r=0.53, p<0.001). In HepG2 liver cells, immunoprecipitated apo CIII from VLDL of participants in the upper quartile of plasma apo CIII sialylation less effectively inhibited LSR-mediated VLDL uptake compared to apo CIII from those in the lower quartile of apo CIII sialylation (28% difference, p=0.02). This difference in inhibition was abolished by removal of sialic acid with neuraminidase. Apo CIII isolated from VLDL of participants with different level of apo CIII sialylation showed similar capacity to inhibit fatty acid release by LPL of control VLDL. VLDL particles with higher apo CIII sialylation also demonstrated a two-fold increase in ApoE. We conclude that a greater apo CIII sialylation together with particle enrichment in apo E allow for more efficient VLDL liver uptake and less liver fat accumulation. The measurement of plasma apo CIII sialylation may be a useful index of triglyceride metabolism and risk of fatty liver.

Cardiovascular effects of dipeptidyl peptidase-4 inhibitors in patients with type 2 diabetes

Cardiovascular (CV) disease is the leading cause of mortality and morbidity in patients with type 2 diabetes mellitus (T2DM). However, improving glycaemic control alone has not decreased CV events. Therapies that improve glycaemic control, CV disease risk factors and CV function are more likely to be successful. Dipeptidyl peptidase-4 (DPP-4) inhibitors prevent breakdown of incretin hormones glucagon-like peptide-1(GLP-1) and glucose-dependent insulinotropic peptide and improve glycaemic control in patients with T2DM. DPP-4 acts on other substrates, many associated with cardioprotection. Thus, inhibition of DPP-4 may lead to elevations in these potentially beneficial substrates. Data from animal studies and small observational studies in humans suggest that DPP-4 inhibitors may potentially reduce CV risk. However, recently completed CV outcome trials in patients with T2DM and CV disease or at high risk of adverse CV events have shown that the DPP-4 inhibitors saxagliptin and alogliptin neither increased nor decreased major adverse CV events.

Dietary models of insulin resistance

Insulin resistance is a significant factor in the development of type 2 diabetes mellitus, however the connection between the Western diet and the development of insulin resistance has not been fully explained. Dietary macronutrient composition has been examined in a number of articles, and diets enriched in saturated fatty acids, and possibly in fructose, appear to be most consistently associated with the development of insulin resistance. However, mechanistic insights into the metabolic effects of such diets are lacking, and merit further study.

Serum amyloid a truncations in type 2 diabetes mellitus

Serum Amyloid A (SAA) is an acute phase protein complex consisting of several abundant isoforms. The N- terminus of SAA is critical to its function in amyloid formation. SAA is frequently truncated, either missing an arginine or an arginine-serine dipeptide, resulting in isoforms that may influence the capacity to form amyloid. However, the relative abundance of truncated SAA in diabetes and chronic kidney disease is not known.

The effect of intensive glucose lowering on lipoprotein particle profiles and inflammatory markers in the Veterans Affairs Diabetes Trial (VADT)

OBJECTIVE

Intensive glucose-lowering therapy (INT) did not reduce macrovascular events in the recent randomized trials, possibly because it did not improve or worsen other traditional or novel cardiovascular risk factors.

RESEARCH DESIGN AND METHODS

Standard plasma lipids, cholesterol content of lipoprotein subfractions, and plasma inflammatory and prothrombotic markers were determined in a subgroup of the Veterans Affairs Diabetes Trial (VADT) participants (n = 266) at baseline and after 9 months of INT or standard therapy.

RESULTS

INT lowered glycated hemoglobin (by a median of 2% vs. a median of 0.7% by standard treatment; P < 0.0001); increased BMI (4 vs. 1%; P < 0.001), total HDL (9 vs. 4%; P < 0.05), HDL2 (14 vs. 0%; P = 0.009), LDL2 (36 vs. 1%; P < 0.0001), and plasma adiponectin (130 vs. 80%; P < 0.01); and reduced triglycerides (-13 vs. -4%; P = 0.02) and small, dense LDL4 (-39 vs. -13%; P < 0.001), but had no effect on levels of plasma apolipoproteins B-100 and B-48, C-reactive protein, interleukin-6, lipoprotein-associated phospholipase A2, myeloperoxidase, fibrinogen, and plasminogen activator inhibitor 1. Incident macrovascular events were associated with baseline interleukin-6 (hazard ratio per each quartile increase 1.33 [95% CI 1.06-1.66]), total LDL (1.25 [1.01-1.55]), apolipoprotein B-100 (1.29 [1.01-1.65]), and fibrinogen (1.26 [1.01-1.57]) but not changes in any cardiovascular risk factors at 9 months.

CONCLUSIONS

INT was associated with improved adiponectin, lipid levels, and a favorable shift in LDL and HDL subfractions after 9 months. These data suggest that the failure of INT to lower cardiovascular outcomes occurred despite generally favorable changes in standard and novel risk factors early in the study.

A randomised trial of salsalate for insulin resistance and cardiovascular risk factors in persons with abnormal glucose tolerance

AIMS/HYPOTHESIS

Chronic sub-acute inflammation contributes to the pathogenesis of type 2 diabetes mellitus and cardiovascular disease. High doses of salicylate reduce inflammation, glucose and triacylglycerols, and may improve insulin sensitivity, suggesting therapeutic potential in impaired fasting glucose and/or impaired glucose tolerance. This trial aimed to evaluate the effect of salsalate vs placebo on insulin resistance and glycaemia in impaired fasting glucose and/or impaired glucose tolerance.

METHODS

We conducted a 12 week, two-centre, randomised, placebo-controlled study to evaluate the effect of salsalate (up to 4 g/day) vs placebo on systemic glucose disposal. Secondary objectives included treatment effects on glycaemia, inflammation and cardiovascular risk factors. Seventy-eight participants with impaired fasting glucose and/or impaired glucose tolerance from two VA healthcare systems were enrolled. Randomisation assignment was provided by the coordinating center directly to site pharmacists, and participants and research staff were blinded to treatment assignment.

RESULTS

Seventy-one individuals were randomised to placebo (n = 36) or salsalate (n = 35). Glucose disposal did not change in either group (salsalate 1% [95% CI -39%, 56%]; placebo 6% [95% CI -20%, 61%], p = 0.3 for placebo vs salsalate). Fasting glucose was reduced by 6% during the study by salsalate (p = 0.006) but did not change with placebo. Declines in glucose were accompanied by declines in fasting C-peptide with salsalate. Insulin clearance was reduced with salsalate. In the salsalate group, triacylglycerol levels were lower by 25% (p = 0.01) and adiponectin increased by 53% (p = 0.02) at the end of the study. Blood pressure, endothelial function and other inflammation markers did not differ between groups. Adipose tissue nuclear factor κB (NF-κB) activity declined in the salsalate group compared with placebo (-16% vs 42%, p = 0.005), but was not correlated with metabolic improvements. The frequency of tinnitus was low but tended to be higher with salsalate therapy (n = 4 vs n = 2).

CONCLUSIONS/INTERPRETATION

In summary, salsalate therapy was well tolerated, lowered fasting glucose, increased adiponectin and reduced adipose tissue NF-κB activity. These changes were not related to changes in peripheral insulin sensitivity, suggesting additional mechanisms for metabolic improvement.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00330733.

FUNDING

Office of Research and Development, Medical Research Service, Department of Veterans Affairs and NIH K24 DK63214.

Incretins and preservation of endothelial function

The endothelium is critical for multiple processes occurring on both sides of the vascular wall including regulation of blood flow, maintenance of blood fluidity and control of inflammation. Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and appears to be a critical determinant of cardiovascular events. It is frequently detected in the early stages of type 2 diabetes and even in pre-diabetes conditions. Risk factors for endothelial dysfunction are numerous and include among others fasting and postprandial hyperglycemia and hyperlipidemia, hypertension, obesity, insulin resistance and inflammation. Many of these conditions can be improved by synthetic glucagon like peptide 1 (GLP-1) mimetics or inhibitors of the main GLP-1 degrading enzyme dipeptidyl peptidase 4 (DPP-4). Acute increases in GLP-1 activity abolish endothelial dysfunction induced by high-fat meals or by hyperglycemia. In vitro and preliminary clinical studies also indicate that GLP-1 or GLP-1 agonists can improve endothelial function by direct action on endothelium. GLP-1 or GLP-1 mimetic effects appear to extend to both conduit arteries and the microvasculature, and may depend on activation of endothelial GLP-1 receptors and downstream nitric oxide production. Additional studies are necessary to confirm improvement of endothelial function after prolonged treatment with incretin based medications as well as the cardiovascular benefit of these agents.

Vascular protective effects of diabetes medications that mimic or increase glucagon-like peptide-1 activity

The incidence of type 2 diabetes (T2DM) is increasing rapidly worldwide and is a strong risk factor for cardiovascular disease (CVD) events. Although hyperglycemia is associated with increased CVD, intensive glycemic control with current diabetes medications has failed in recent large clinical trials to reduce macrovascular disease, demonstrating that intensive glucose control alone is insufficient to reduce major CVD events. A new approach to lowering glucose takes advantage of the incretin system and medications that raise or mimic glucagon-like peptide-1 (GLP-1). These agents not only improve glycemic control by mechanisms that minimize hypoglycemia, but also improve lipoprotein profiles, blood pressure control and weight loss. There is also increasing evidence that at least pharmacologic concentrations of GLP-1 or GLP-1 mimetics may improve endothelial function and have direct vascular-protective effects. Importantly, these benefits transpired even before the improvements in weight and overall glucose control occurred. It remains to be seen whether the chronic effects of GLP-1 activity on glucose, CVD risk factors and vascular function will lead to lasting beneficial effects on CVD risk. If preliminary findings on the vasculoprotective effects of GLP-1 agents are validated and confirmed in longitudinal clinical trials, this class of drugs may represent a paradigm shift in the treatment of vascular disease in both patients with diabetes and in non-diabetic individuals at high risk for CVD. Recent patents regarding GLP-1 agents are discussed in this review article.

Postprandial hyperlipidemia, endothelial dysfunction and cardiovascular risk: focus on incretins

Cardiovascular disease (CVD) risk in type 2 diabetes (T2DM) is only partially reduced by intensive glycemic control. Diabetic dyslipidemia is suggested to be an additional important contributor to CVD risk in T2DM. Multiple lipid lowering medications effectively reduce fasting LDL cholesterol and triglycerides concentrations and several of them routinely reduce CVD risk. However, in contemporary Western societies the vasculature is commonly exposed to prolonged postprandial hyperlipidemia. Metabolism of these postprandial carbohydrates and lipids yields multiple proatherogenic products. Even a transient increase in these factors may worsen vascular function and induces impaired endothelial dependent vasodilatation, a predictor of atherosclerosis and future cardiovascular events. There is a recent increased appreciation for the role of gut-derived incretin hormones in controlling the postprandial metabolic milieu. Incretin-based medications have been developed and are now used to control postprandial hyperglycemia in T2DM. Recent data indicate that these medications may also have profound effects on postprandial lipid metabolism and may favorably influence several cardiovascular functions. This review discusses (1) the postprandial state with special emphasis on postprandial lipid metabolism and its role in endothelial dysfunction and cardiovascular risk, (2) the ability of incretins to modulate postprandial hyperlipidemia and (3) the potential of incretin-based therapeutic strategies to improve vascular function and reduce CVD risk.

Exenatide suppresses postprandial elevations in lipids and lipoproteins in individuals with impaired glucose tolerance and recent onset type 2 diabetes mellitus

OBJECTIVE

Chronic exenatide treatment in type 2 diabetes is associated with improved glucose control and fasting lipid levels, as well as weight loss. Less established is whether exenatide directly reduces postprandial lipid and lipoprotein levels without the reduction in body weight or fasting glucose and triglycerides levels that frequently occur with prolonged therapy. Therefore, the effect of a single injection of exenatide on postprandial lipids, remnant lipoproteins, and apolipoproteins was studied.

METHODS

A double-blinded, randomized, placebo-controlled, crossover study was conducted in 35 subjects (31 men and 4 women) with impaired glucose tolerance (n=20) or recent onset type 2 diabetes (n=15). A single subcutaneous injection of exenatide (10 microg) or normal saline was administered just prior to a high-calorie, fat-enriched breakfast meal. Concentrations of triglycerides (TG), apolipoproteins B-48 and CIII, non-esterified fatty acids (NEFA), and remnant lipoprotein (RLP) cholesterol and TG in serum or plasma were measured prior to the injection and for up to 8 h postprandially.

RESULTS

Exenatide markedly reduced postprandial elevation of TG, apolipoproteins B-48 and CIII, RLP-cholesterol and RLP-triglyceride (all p<0.001). Postprandial declines in NEFA were less pronounced but persisted longer with exenatide compared to placebo (p<0.05). These effects of exenatide were not affected either by glucose tolerance status or by treatment with statins.

CONCLUSION

These results demonstrate that exenatide acutely and profoundly inhibits postprandial excursions of proatherogenic lipids and lipoproteins and may offer additional cardiovascular risk reduction (NCT00974272).

High prevalence of prediabetes and diabetes in a population exposed to high levels of an organochlorine cocktail

AIMS/HYPOTHESIS

A heavily polluted area of Eastern Slovakia was targeted by the PCBRISK cross-sectional survey to search for possible links between environmental pollution and both prediabetes and diabetes.

METHODS

Associations of serum levels of five persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), 2,2'-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), 2,2'-bis(4-chlorophenyl)-1,1,1-trichloro-ethane (p,p'-DDT), hexachlorobenzene (HCB) and beta-hexachlorocyclohexane (beta-HCH), with prediabetes and diabetes were investigated in 2,047 adults. Diabetes and prediabetes were diagnosed by fasting plasma glucose in all participants and by OGTT in 1,220 compliant participants.

RESULTS

Our population was stratified in terms of individual POPs quintiles and associations between environmental pollution, prediabetes and diabetes were investigated. Prevalence of prediabetes and diabetes increased in a dose-dependent manner, with individuals in upper quintiles of individual POPs showing striking increases in prevalence of prediabetes as shown by OR and 95% CI for PCBs (2.74; 1.92-3.90), DDE (1.86; 1.17-2.95), DDT (2.48; 1.77-3.48), HCB (1.86; 1.7-2.95) and beta-HCH (1.97; 1.28-3.04). Interestingly, unlike PCBs, DDT and DDE, increased levels of HCB and beta-HCH seemed not to be associated with increased prevalence of diabetes. Nevertheless, individuals in the 5th quintile of the variable expressing the cumulative effect of all five POPs (sum of orders) had a more than tripled prevalence of prediabetes and more than six times higher prevalence of diabetes when compared with the 1st referent quintile.

CONCLUSIONS/INTERPRETATION

Increasing serum concentrations of individual POPs considerably increased prevalence of prediabetes and diabetes in a dose-dependent manner. Interaction of industrial and agricultural pollutants in increasing prevalence of prediabetes or diabetes is likely.

Improvement of postprandial endothelial function after a single dose of exenatide in individuals with impaired glucose tolerance and recent-onset type 2 diabetes

OBJECTIVE

Endothelial dysfunction is frequently present in individuals with insulin resistance or type 2 diabetes and can be induced by high-fat or high-carbohydrate meals. Because exenatide reduces postprandial glucose and lipid excursions, we hypothesized that it may also improve postprandial endothelial function.

RESEARCH DESIGN AND METHODS

In a double-blinded randomized crossover design, postprandial endothelial function was examined in 28 individuals with impaired glucose tolerance or recent-onset type 2 diabetes after a single injection of exenatide or placebo given just before a high-fat meal. Endothelial function was determined with peripheral arterial tonometry pre- and postprandially.

RESULTS

Postprandial endothelial function was higher after exenatide compared with placebo (P = 0.0002). In the placebo phase, postprandial change in endothelial function was inversely associated with mean postprandial concentrations of triglycerides (r = -0.62, P = 0.0004). Changes in postprandial triglyceride concentrations explained 64% of exenatide's effect on postprandial endothelial function.

CONCLUSIONS

Exenatide ameliorates postprandial endothelial dysfunction after a high-fat meal.

mRNA concentrations of MIF in subcutaneous abdominal adipose cells are associated with adipocyte size and insulin action

Objective

To determine whether the mRNA concentrations of inflammation response genes in isolated adipocytes and in cultured preadipocytes are related to adipocyte size and in vivo insulin action in obese individuals.

Design

Cross-sectional inpatient study.

Subjects

Obese Pima Indians with normal glucose tolerance.

Measurements

Adipocyte diameter (by microscope technique; n=29), expression of candidate genes (by quantitative real-time PCR) in freshly isolated adipocytes (monocyte chemoattractant protein [MCP] 1 and MCP2, macrophage inflammatory protein [MIP] 1α, MIP1β and MIP2, macrophage migration inhibitory factor [MIF], tumor necrosis factor alpha, interleukin [IL] 6 and IL8; n=22) and cultured preadipocytes (MCP1, MIP1α, MIF, IL6 and matrix metalloproteinase 2; n=33) from subcutaneous abdominal adipose tissue (by aspiration biopsy, n=34), body fat by dual-energy X-ray absorptiometry, glucose tolerance by 75-gram oral glucose tolerance test, and insulin action by euglycemic-hyperinsulinemic clamp (insulin infusion rate 40 mU/m².min)(all n=34).

Results

MIF was the only gene whose expression in both freshly isolated adipocytes and cultured preadipocytes was positively associated with adipocytes diameter and negatively associated with peripheral and hepatic insulin action (all P<0.05). In multivariate analysis, the association between adipocyte MIF mRNA concentrations and adipocytes diameter was independent of percent body fat (P=0.03), whereas adipocyte MIF mRNA concentrations but not adipocytes diameter independently predicted peripheral insulin action. The mRNA expression concentrations of MIF gene in adipocytes were not associated with plasma concentrations of MIF, but were negatively associated with plasma adiponectin concentrations (P=0.004). In multivariate analysis, adipocyte MIF RNA concentrations (P=0.03) but not plasma adiponectin concentrations (P=0.4) remained a significant predictor of insulin action.

Conclusions

Increased expression of MIF gene in adipose cells may be an important link between obesity characterized by enlarged adipocytes and insulin resistance in normal glucose tolerant people.

Multiple adverse thyroid and metabolic health signs in the population from the area heavily polluted by organochlorine cocktail (PCB, DDE, HCB, dioxin)

Background

Several our previous studies showed associations of increasing blood level of persistent organochlorinated pollutants (POPs) with individual thyroid and metabolic adverse health signs in subjects from heavily polluted area (POLL) compared to these from the area of background pollution (BCGR). In this study we present increasing number of subjects with multiple adverse signs positively associated with blood level of polychlorinated biphenyls (PCBs) which is used as a marker of other POPs cocktail.

Methods

In a total of 2046 adults (834 males and 1212 females; age range 21–75) from POLL and BCGR the serum level of major POPs such as of 15 most abundant PCBs congeners, dichlorodiphenyl-dichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB) was estimated by high resolution gas chromatography. In addition, the data on thyroid volume by ultrasound and body mass index were obtained and serum level of thyroperoxidase and thyrotropin receptor antibodies as well as that of free thyroxine, total triiodothyronine, thyrotropin, thyroglobulin, fasting glucose and insulin, cholesterol and triglycerides was measured. Thus, a total of 13 adverse signs were defined and the interrelations between PCBs level and increasing number of subjects with increasing number of adverse signs were evaluated.

Results

Because of high correlation between major POPs (PCB, DDE and HCB), for this purpose the level of PCBs was considered as a marker also for the presence of DDE and HCB. Thus, if all data obtained from 2046 subjects were stratified according to quintiles of PCBs level, highly significant increase was found (p < 0.02 to 0.0000 by chi-sqauare) for the frequency of 8 among 13 signs, while the increase of one additional sign was slightly above significance limit and that in 4 other was not significant. Also the number of subjects with multiple adverse signs was significantly higher in POLL than in BCGR. For instance, in BCGR area (1038 subjects; median PCB level of 744 ng/g and 5%–95% range of 423 – 1329 ng/g serum lipids) there were 84 (8.1%) cases with 6 or 7 adverse health signs, while in POLL area (1008 subjects; median PCB level of 1892 ng/g; 5%–95% range of 685 – 9016 ng/g) the prevalence of respective cases was twice as high (195 cases = 19.3%; p < 0.001 by chi-square). For the subjects with the same PCB levels, but with 8 or 9 adverse signs the respective values were 22/1038 (2.1%) vs. 54/1008 (5.3%; p < 0.001).

Conclusion

Significantly higher accumulation of adverse signs in subjects with high POPs level was found in POLL thus supporting the conclusion that POPs appear to increase the prevalence of several subclinical and overt thyroid and metabolic disorders.

The effect of salsalate on insulin action and glucose tolerance in obese non-diabetic patients: results of a randomised double-blind placebo-controlled study

AIM/HYPOTHESIS

Low-grade inflammation may contribute to obesity-related insulin resistance and has been associated with increased risk of type 2 diabetes mellitus. The present study evaluated whether treatment with salsalate, a traditional anti-inflammatory medication, would improve insulin action in obese non-diabetic individuals.

METHODS

The study was a randomised, double-blind, placebo-controlled, parallel trial conducted at the inpatient clinical research unit of the NIDKK (Phoenix, AZ, USA). Participants were 54 adults (18 to 45 years of age) with BMI >or= 30 kg/m(2). The intervention was salsalate (3 g/day, n = 28) or identical placebo (n = 26) for 7 days. The allocation was kept concealed by giving the investigator only a number corresponding to a vial of placebo or salsalate sequentially randomised in blocks by sex. Main outcomes were changes in insulin action assessed as rate of glucose disposal (R (d)) by euglycaemic-hyperinsulinaemic clamp (insulin infusion rate 40 mU m(-2) min(-1)) and glucose tolerance by 75 g OGTT.

RESULTS

The study was completed by 47 participants, of which 40 were analysed (salsalate n = 22, placebo n = 18). Salsalate treatment resulted in decreased fasting plasma glucose concentration (mean [SD]; 4.83 [0.28] vs 5.11 [0.33] mmol/l, p = 0.001) and glucose AUC during the OGTT (p = 0.01), and in increased R (d) (20 [8] vs 18 [6] micromol [kg estimated metabolic body size](-1) min(-1), p = 0.002), while there was no significant change in these variables with placebo (p > 0.3 for all). The effect of salsalate on R (d) disappeared (p = 0.9) after normalising to increased insulin concentrations (701 [285] vs 535 [201] pmol/l, p < 0.0001) measured during the clamp. No side effects of salsalate were observed during the study.

CONCLUSIONS/INTERPRETATION

The glucose-lowering potential of salicylates appears to be due to effects on insulin concentration rather than improved insulin action. Salicylate-based compounds may be useful for the treatment and prevention of type 2 diabetes.

Macrophage content in subcutaneous adipose tissue: associations with adiposity, age, inflammatory markers, and whole-body insulin action in healthy Pima Indians

OBJECTIVE

In severely obese individuals and patients with diabetes, accumulation and activation of macrophages in adipose tissue has been implicated in the development of obesity-associated complications, including insulin resistance. We sought to determine whether in a healthy population, adiposity, sex, age, or insulin action is associated with adipose tissue macrophage content (ATMc) and/or markers of macrophage activation.

RESEARCH DESIGN AND METHODS

Subcutaneous ATMc from young adult Pima Indians with a wide range of adiposity (13-46% body fat, by whole-body dual-energy X-ray absorptiometry) and insulin action (glucose disposal rate 1.6-9 mg/kg estimated metabolic body size/min, by glucose clamp) were measured. We also measured expression in adipose tissue of factors implicated in macrophage recruitment and activation to determine any association with ATMc and insulin action.

RESULTS

ATMc, as assessed by immunohistochemistry (Mphi) and by macrophage-specific gene expression (CD68, CD11b, and CSF1R), were correlated with percent body fat, age, and female sex. Gene expression of CD68, CD11b, and CSF1R but not Mphi was correlated negatively with glucose disposal rate but not after adjustment for percent body fat, age, and sex. However, adipose tissue expression of plasminogen activator inhibitor type-1 (PAI-1) and CD11 antigen-like family member C (CD11c), markers produced by macrophages, were negatively correlated with adjusted glucose disposal rate (r = -0.28, P = 0.05 and r = -0.31, P = 0.03).

CONCLUSIONS

ATMc is correlated with age and adiposity but not with insulin action independent of adiposity in healthy human subjects. However, PAI-1 and CD11c expression are independent predictors of insulin action, indicating a possible role for adipose tissue macrophage activation.

Increased thyroid volume, prevalence of thyroid antibodies and impaired fasting glucose in young adults from organochlorine cocktail polluted area: outcome of transgenerational transmission?

In 137 females (F) and 94 males (M) aged 21-35 years from organochlorines (OCs) polluted area (POLL) increased thyroid volume (ThV), prevalence of antibodies to thyroperoxidase (TPOab), thyrotropin receptor (TRab) and of impaired fasting glucose (IFG) was found compared to 116 F and 107 M from background pollution area (BCGR). In F and M from POLL also strikingly increased level of PCBs, DDE and HCB was found. Such findings were compared to the generation of their parents aged 41-55 years consisting of 320F/213M from POLL and 406F/231M from BCGR. However, in spite of strikingly lower level of those OCs in young adults from POLL, they showed about the same prevalence of adverse health signs as the old generation. From such reason 44 young F and 40 young M with lowest PCBs level from POLL were selected to obtain nearly the same PCB level as found in all young F and M from BCGR. In such PCB adjusted groups the prevalence of TPOab, TRab, IFG and increased ThV was still significantly higher than that in all young subjects from BCGR. At the same time, also the level of DDE and HCB in such PCBs adjusted groups was considerably lower. It was concluded that such adverse effects in young adults from POLL possibly did not result from their actual OCs levels, but very likely from their exposure to high OCs levels of their mothers during their prenatal and perinatal life. Thus, the data may be compatible with present views on transgenerational transmission of endocrine disruptors action.

Distribution of subcutaneous fat predicts insulin action in obesity in sex-specific manner

The pattern of adipose tissue (AT) distribution is an important predictor of metabolic risk. The aim of this study was to analyze the association of peripheral (insulin-mediated glucose disposal--M) and hepatic (suppression of endogenous glucose production--EGP) insulin action with abdominal (subcutaneous abdominal AT-SAAT intraabdominal AT-IAAT) and thigh AT depots in obese individuals. Fifty-seven Pima Indians with normal glucose tolerance underwent magnetic resonance imaging (MRI) and euglycemic-hyperinsulinemic clamp. M was negatively related to intraperitoneal IAAT (P = 0.02) and deep SAAT (P = 0.03). Suppression of EGP was negatively related to total (P < 0.05) or deep SAAT (P < 0.05 and P = 0.01, respectively), and total or intraperitoneal IAAT (P = 0.009 and P = 0.002, respectively). A significant interaction with sex was found in the association between superficial SAAT and M, so that in women, but not men, M negatively correlated with superficial SAAT (P = 0.02). In stepwise regression analysis, both M (r2 = 0.09) and EGP suppression (r2 = 0.17) were associated only with intraperitoneal IAAT in the whole group. In the sex-specific analysis (because of the significant interaction), lower M was associated with higher deep SAAT (r2 = 0.15) in combination with lower superficial SAAT (r2 = 0.09) in men, and with higher superficial SAAT (r2 = 0.29) in combination with lower thigh subcutaneous AT (r2 = 0.16) in women. Although intraperitoneal IAAT and deep SAAT were major predictors of peripheral and hepatic insulin action in obese Pima Indians, the largest variance in M rate was explained in a sex-specific manner by relative size of subcutaneous AT depots.

Adipokine protein expression pattern in growth hormone deficiency predisposes to the increased fat cell size and the whole body metabolic derangements

CONTEXT

GH deficiency (GHD) in adults is associated with central adiposity, dyslipidemia, and insulin resistance.

OBJECTIVE

The objective of the study was to test the hypothesis that GHD might change the spectrum of adipokines and thus influence the adipose tissue and the whole-body metabolic and inflammatory status leading to development of insulin resistance.

DESIGN

This was a single-center observational study with a cross-sectional design.

PARTICIPANTS AND METHODS

Protein arrays were used to characterize adipokines expressed in the sc adipose tissue obtained from young GHD adults and compared with age-, gender-, and body mass index (BMI)-matched group of healthy individuals. All subjects underwent an oral glucose tolerance test, euglycemic hyperinsulinemic clamp, and magnetic resonance imaging examination.

RESULTS

Presence of abdominal obesity, enlarged adipocytes, increased circulating high-sensitivity C-reactive protein, impaired glucose tolerance, and decreased insulin action were found in GHD. Changes in adipokine protein expression due to GHD were highly dependent on the obesity phenotype. Lean GHD individuals (BMI approximately 23 kg/m(2)) had decreased protein levels for stem cell factor and epithelial growth factor, indicating a possible defect in adipocyte differentiation and proliferation. Decrease of vascular endothelial growth factor, stromal cell-derived factor, angiopoietin-2, and brain-derived neurotrophic factor advocated for attenuated angiogenesis and neurogenesis. Presence of obesity (BMI approximately 31 kg/m(2)) eliminated these inhibitory effects. However, adipose tissue expansion in GHD individuals was paralleled by an elevation of adipose tissue proinflammatory cytokines (IL-1beta, interferon-gamma) and chemoattractants (interferon-inducible T cell alpha-chemoattractant, monocyte chemotactic protein-2, monocyte chemotactic protein-3, eotaxin).

CONCLUSION

Our data demonstrate that GHD modulates adipokine and cytokine protein expression pattern, which might influence the adipose tissue growth and differentiation and predispose to tissue hypoxia, inflammation, and a defect in the whole-body insulin action.

Free triiodothyronine plasma concentrations are positively associated with insulin secretion in euthyroid individuals

BACKGROUND

Thyroid hormones (TH) may influence glucose metabolism. Hyperthyroid subjects have higher insulin secretion rates when compared with euthyroid individuals.

OBJECTIVE

To evaluate the association between TH concentrations and insulin secretion in euthyroid, healthy Pima Indian adults (n=55, 29+/-7 years, females/males 36/19) with normal glucose tolerance (NGT) admitted to a Clinical Research Unit.

METHODS

TSH, free thyroxine (FT4), 3,5,3'-L-tri-iodothyronine (FT3), and fasting plasma insulin (FPI) concentrations were measured in fasting plasma samples, percentage of body fat (%BF) by dual energy x-ray absorptiometry (DXA), acute insulin response (AIR), and incremental area under the curve (AUC) of insulin in response to a 25 g intravenous glucose tolerance test (IVGTT) and 75 g oral glucose tolerance test (OGTT) respectively and insulin action (M) during an euglycemic clamp.

RESULTS

FT3 concentrations were associated with FPI, AIR, and insulin AUC both before (r=0.33, P=0.01; r=0.29, P=0.03; and r=0.35, P=0.008 respectively) and after adjustment for age, sex, %BF, glucose (fasting concentrations or glucose AUC), and M (beta=0.09, P=0.01; beta=0.16, P=0.03; and beta=0.24, P=0.0007 respectively). No associations were found for TSH or FT4.

CONCLUSION

FT3 was associated with several measurements of insulin secretion in euthyroid individuals with NGT. T3 concentrations may play a role in the regulation of insulin secretion.

Increased fat accumulation in liver may link insulin resistance with subcutaneous abdominal adipocyte enlargement, visceral adiposity, and hypoadiponectinemia in obese individuals

BACKGROUND

Enlargement of adipocytes from subcutaneous abdominal adipose tissue (SAT), increased intrahepatic lipid content (IHL), intramyocellular lipid content (IMCL), and low circulating adiponectin concentrations are associated with insulin resistance.

OBJECTIVE

Because adiponectin increases fat oxidation in skeletal muscle and liver, and the expression of the adiponectin gene in SAT is inversely associated with adipocyte size, we hypothesized that hypoadiponectinemia links hypertrophic obesity with insulin resistance via increased IMCL and IHL.

DESIGN

Fifty-three obese Pima Indians with a mean (+/-SD) age of 27 +/- 8 y, body fat of 35 +/- 5%, and normal glucose regulation (normal fasting and 2-h glucose concentration per WHO 1999 criteria) underwent euglycemic-hyperinsulinemic clamp, biopsies of SAT and vastus lateralis muscle, and magnetic resonance imaging of the abdomen.

RESULTS

Adipocyte diameter (AD) correlated positively with body fat (P < 0.0001) and IHL (estimated from magnetic resonance imaging intensity of liver; P = 0.047). No association was found between AD and plasma adiponectin or IMCL. Plasma adiponectin negatively correlated with type II IMCL (IIA, P = 0.004; IIX, P = 0.009) or IHL (P = 0.02). In a multivariate analysis, plasma adiponectin, AD, and visceral adipose tissue (VAT) independently predicted IHL. Low insulin-mediated glucose disposal was associated with low plasma adiponectin (P = 0.02) and high IHL (P = 0.0003), SAT (P = 0.02), and VAT (P = 0.04). High IHL was the only predictor of reduced insulin-mediated suppression of hepatic glucose production (P = 0.02) and the only independent predictor of insulin-mediated glucose disposal in a multivariate analysis.

CONCLUSIONS

Increased lipid content in the liver may independently link hypoadiponectinemia, hypertrophic obesity, and increased visceral adiposity with peripheral and hepatic insulin resistance.

Adipogenic human adenovirus Ad-36 induces commitment, differentiation, and lipid accumulation in human adipose-derived stem cells

Human adenovirus Ad-36 is causatively and correlatively linked with animal and human obesity, respectively. Ad-36 enhances differentiation of rodent preadipocytes, but its effect on adipogenesis in humans is unknown. To indirectly assess the role of Ad-36-induced adipogenesis in human obesity, the effect of the virus on commitment, differentiation, and lipid accumulation was investigated in vitro in primary human adipose-derived stem/stromal cells (hASC). Ad-36 infected hASC in a time- and dose-dependent manner. Even in the presence of osteogenic media, Ad-36-infected hASC showed significantly greater lipid accumulation, suggestive of their commitment to the adipocyte lineage. Even in the absence of adipogenic inducers, Ad-36 significantly increased hASC differentiation, as indicated by a time-dependent expression of genes within the adipogenic cascade-CCAAT/Enhancer binding protein-beta, peroxisome proliferator-activated receptor-gamma, and fatty acid-binding protein-and consequentially increased lipid accumulation in a time- and viral dose-dependent manner. Induction of hASC to the adipocyte state by Ad-36 was further supported by increased expression of lipoprotein lipase and the accumulation of its extracellular fraction. hASC from subjects harboring Ad-36 DNA in their adipose tissue due to natural infection had significantly greater ability to differentiate compared with Ad-36 DNA-negative counterparts, which offers a proof of concept. Thus, Ad-36 has the potential to induce adipogenesis in hASC, which may contribute to adiposity induced by the virus.

Possible effects of persistent organochlorinated pollutants cocktail on thyroid hormone levels and pituitary-thyroid interrelations

In polluted district of Michalovce in East Slovakia (POLL) and two districts with background pollution (BCGR) 2046 adults (834 males and 1212 females aged 20-75 years) were examined. Serum levels of thyrotropin (TSH), free thyroxine (FT4), total triiodothyronine (TT3) and antithyroperoxidase antibodies (TPOab) were estimated by electrochemiluminiscent assay and also these of 15 polychlorinated biphenyl congeners (PCBs), p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and hexachlorocyclohexane were measured by high resolution gas chromatography/mass spectrometry. In addition, also dioxins, furans, coplanar- and mono-ortho-PCBs as well as selected hydroxylated and methylsulphonated PCBs and DDE metabolites were measured by appropriate methods based on gas chromatography/mass spectrometry principle. In POLL significantly higher levels of all organochlorines were found than these in BCGR. When pooled values from both areas were stratified in terms of PCBs level and treated as continuous variables, positive association of PCBs with FT4 and TT3 was found, the latter two being also mutually associated. However, within the category of PCBs level <530 ng/glipid (n=232) the association between PCBs and both the FT4 (p<0.09) and TT3 (p<0.03) was negative and any association of these was not found within the category of PCBs level of 531-1000 ng/g (n=691). In contrast, in the category of 531-2000 ng/g (n=1307) positive association appeared between PCBs and FT4 (p<0.001) as well as TT3 (p<0.05). Highly significant association of PCBs with FT4 (p<0.001) was further found in the categories with PCBs level of 1001-101414 ng/g (n=1307) and 2001-101414 (n=1123), while significant association with TT3 was observed only in the category of 531-2000 ng/g. Such findings suggest possible threshold level in positive effect of PCBs on FT4 and TT3 level which seems to be individual and located somewhere around the PCBs level of 1000 ng/g. However, highly significant negative association of both FT4 and TT3 with TSH was found in each of above indicated PCBs categories. Considerable difference in FT4 and TT3 level between large groups of subjects with the same range of PCBs level was also found suggesting different individual susceptibility to the effects of organochlorines. Among a total of 26 cases from POLL with very low TSH level (<0.5 mU l(-1)) 13 cases showed very high level of PCBs, FT4 and TT3, thus supporting a hypothesis on a novel sporadic form of high PCBs related peripheral subclinical hyperthyroidism possibly resulting from the long-term disruption of equilibrium between bound and free thyroxine in plasma by high PCBs level followed by a striking inhibition of TSH release from the pituitary.

Protein array reveals differentially expressed proteins in subcutaneous adipose tissue in obesity

OBJECTIVE

Many adipokines, inflammatory cytokines, and other proteins produced by adipose tissue have been shown to be involved in the development of obesity-related insulin resistance. Nevertheless, new factors that play an important role in these processes are still emerging. Therefore, we screened the level of 120 different proteins in biopsies of subcutaneous adipose tissue (ScAT) of lean and obese subjects.

RESEARCH METHODS AND PROCEDURES

All studied volunteers (12 obese with BMI >30 and 6 lean with BMI <25 kg/m(2)) were young, clinically healthy, and drug-naive males with normal glucose tolerance. The ScAT was obtained by a needle biopsy from the umbilical region. Protein levels were assessed in adipose tissue lysates using protein arrays; mRNA levels were determined with the aid of real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The obese subjects had higher fasting plasma glucose (although within the normal range) and insulin levels, increased high sensitivity C-reactive protein (hsCRP) in circulation, and decreased in vivo insulin action. Using the protein array technique, it was shown that of 120 proteins measured, 27 showed higher levels (leptin, HGF, EGF-R, FGF-6, IGF-1sR, Fas/Apo-1, ENA-78, PARC, lymphotactin, HCC-4, IL-10, IL-1a, IL-1R1, IL-1R4, IL-12p70, angiopoietin-2, Axl, Dtk, MIF, MIP-1a, -1b, -3b, MSP-a, osteoprotegerin, TECK, TIMP-1, -2) and only one (RANTES) showed a lower level in ScAT of obese subjects when compared with the lean controls (p < 0.05). The real-time RT-PCR confirmed the results of protein arrays for leptin, MIF, MIP-1a, TIMP-2, adiponectin, IL-6, and TNF-alpha but not for RANTES.

DISCUSSION

To our knowledge, this is the first protein array data on a very early dysregulation of ScAT protein levels in insulin-resistant obese, but apparently healthy, subjects with normal glucose tolerance.

Thyroid ultrasound volume, structure and function after long-term high exposure of large population to polychlorinated biphenyls, pesticides and dioxin

We examined 2,046 adults (834 males and 1,212 females aged 20-75 years) from polluted district in East Slovakia (POLL) and two neighboring upstream and upwind located districts of background pollution (BCGR). By ultrasound we estimated the thyroid volume (ThV), hypoechogenicity (HYE), nodules and cysts. Serum levels of thyrotropin (TSH), thyroperoxidase antibodies (TPOab) and thyroglobulin were estimated by electrochemiluminiscent assay and these of 15 PCB congeners, p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and hexachlorocyclohexane by high-resolution gas chromatography. In 320 subjects also selected hydroxylated and methylsulfonated PCB metabolites, polychlorinated dibenzo-dioxins (PCDDs), -furans (PCDFs), five dioxin-like coplanar and eight mono-ortho PCB congeners were estimated. Urinary iodine was measured by automatic microplate method. Reciprocal positive association was found between three major POPs (PCBs, DDE and HCB), the levels of these and also PCDDs plus PCDFs in polluted area being considerably higher than in background pollution area. ThV in groups of males and females from POLL with high PCBs level was significantly higher (p<0.001 by t-test) then in age and sex matched groups from BCGR with low PCBs level. In 1,048 males and females aged <60 years with serum PCBs level >1,000 ng g(-1) lipid (median=1,756 ng g(-1)) a significant effect of age on ThV was found (p<0.01 by ANOVA), while in 921 respective subjects with PCBs level <1,000 ng g(-1) (median=661 ng g(-1)) it was not. These findings supported the view on the additional effect of PCBs on ThV other than that of age. Since the urinary iodine in both districts showed optimal range, any interfering effect of unsatisfactory iodine intake on ThV may be excluded. The frequency of autoimmune thyroiditis signs such as HYE, increased serum level of TPOab and TSH resulting in subclinical or overt thyroid hypofunction was positively associated with sex, age and organochlorine levels. The increase of such frequency in males with POPs levels was much more abrupt than that in females. No considerable differences in the frequency of thyroid nodules as related to PCBs level were found.