Glucose-intolerant Subjects Research Articles

1505-P: Plasma Glucose Level at 1h Post 75g OGTT Is the Best Predictor of the Development of Glucose Intolerance in Subjects with Normal Glucose Tolerance—The Toon Health Study

Background: Although glucose intolerance (GI) is diagnosed by fasting and 2h plasma glucose (PG) levels during a 75g OGTT, the upper limit of 1h PG level remains to be undefined in subjects with NGT. Previous report focusing on changes from NGT + IGT to diabetes has reported that 1h PG with ≥155 mg/dl is the risk for future diabetes in the world. However, IGT is well known as a risk factor for cardiovascular disease, few studies have focused on changes from NGT to GI. We therefore conducted a 5-year prospective study intended for NGT subjects to clarify the best predictor of the development of GI. Methods: To diagnose GI, we performed a 75gOGTT. We enrolled 1383 NGT subjects from The Toon Health Study. Finally, we analyzed 981 individuals with NGT who had a repeat health checkup. To investigate valuable predictive factors of progression of GI, we performed ROC curve analyses and compared fasting PG, 1h post OGTT, 2h post OGTT, and HbA1c. Results: ROC curve analyses revealed that 1h post OGTT was the best predictor of the development of GI in NGT (sensitivity 66%, specificity 74%, at a cutoff value of 149 mg/dl). In NGT with 1h PG>149mg/dl, odd ratio for the development of GI was 4.7 (95% CI: 3.25-6.80) compared to the reference after adjustment for age, sex, and BMI (p<0.0001). Conclusions: PG level at 1h post 75g OGTT was the best predictor of the development of GI in NGT. Disclosure M. Takakado: None. Y. Takata: None. T. Hadate: None. Y. Matsushita: None. R. Kawamura: None. K. Maruyama: None. I. Saito: None. H. Osawa: None.

Quantitative Proteomic Analysis on Human Islets—New Markers of Cellular and Metabolic Dysfunction

The pathogenesis of type 2 diabetes is characterized by a progressive β-cell dysfunction resulting in both quantitative and qualitative loss of insulin secretion. However, the molecular mechanisms underlying this progressive functional loss are still unknown. The aim of the study is to highlight changes in the proteome of pancreatic human islets that can anticipate and eventually predict diabetes’ onset. High performance liquid chromatography mass spectrometry (HPLC-MS) analysis was applied to islets isolated by laser capture microdissection (LCM) from human samples of both diabetic and no diabetic subjects, underwent to duodeno-cefalopancreatectomy for extra-pancreatic, low grading tumors. The subjects were classified on the basis of glucose tolerance assessed by an OGTT before surgery in normal tolerant (NGT, n:7), glucose intolerant (IGT, n:5) and diabetic subjects (T2DM, n:2). Qualitative and quantitative analysis were performed to detect differential protein expression among the 3 study’s groups. Sixty-seven proteins were found to be differentially regulated in diabetic subjects compare to NGT, with 29 upregulated and 38 downregulated proteins, while 95 proteins were differentially expressed in IGT compare to NGT with 49 upregulated and 46 downregulated. These proteins are mainly involved in cellular and metabolic processes. In particular IGT and DM, compared to NGT, showed a lower expression of proteins involved in cell proliferation such as PURA and NAP1L1, as well as proteins involved in the insulin cleavage process, like ERO1B. While other proteins involved in endoplasmic reticulum stress, CASP14, ERP27 and PDIA3, resulted upregulated in both IGT and DM compare to NGT. Our data suggest that metabolic and cellular processes of islet cells are already dysregulated in patients with impaired glucose tolerance, highlighting some proteins as potential early markers of β-cell dysfunction and novel therapeutic targets to slow the progression to type 2 diabetes. Disclosure C. Cefalo: None. T. Mezza: None. R. Kulkarni: None. A. Giaccari: Advisory Panel; Self; Sanofi-Aventis. Speaker's Bureau; Self; AstraZeneca, Merck Sharp & Dohme Corp., Amgen Inc..

Lowered fasting chenodeoxycholic acid correlated with the decrease of fibroblast growth factor 19 in Chinese subjects with impaired fasting glucose

The gut-derived hormone Fibroblast growth factor 19 (FGF19) could regulate glucose metabolism and is induced by bile acids (BAs) through activating Farnesoid X Receptor (FXR). FGF19 was found to decrease in subjects with isolated-impaired fasting glucose (I-IFG) and type 2 diabetes mellitus (T2DM). However, the reason for the change of FGF19 in subjects with different glucometabolic status remained unclear. Here we measured six BAs including chenodeoxycholic acid (CDCA), cholic acid, deoxycholic acid, their glycine conjugates and FGF19 levels during oral glucose tolerance test (OGTT) in normal glucose tolerance (NGT), isolated-impaired glucose tolerance, I-IFG, combined glucose intolerance (CGI) and T2DM subjects. After OGTT, serum FGF19 peaked at 120 min in all subjects. Glycine conjugated BAs peaked at 30 min, while free BAs did not elevated significantly. Consistent with the decrease trend in FGF19 levels, fasting serum CDCA levels in subjects with I-IFG, CGI and T2DM were significantly lower than NGT subjects (P < 0.05). Fasting serum CDCA was independently associated with FGF19. CDCA strongly upregulated FGF19 mRNA levels in LS174T cells in a dose- and time-dependent manner. These results suggest that the decrease of FGF19 in subjects with I-IFG was at least partially due to their decrease of CDCA acting via FXR.

Soluble dietary fibre partially hydrolysed guar gum markedly impacts on postprandial hyperglycaemia, hyperlipidaemia and incretins metabolic hormones over time in healthy and glucose intolerant subjects

Dietary fibre intakes have consistently been associated with reduced risk of diabetes and metabolic syndrome. We investigated in 12 healthy subjects if administration of dietary fibre partially hydrolysed guar gum (PHGG) induces beneficial impact on hyperglycaemia, hyperlipidaemia and incretins metabolic hormones. Administration of 6 g/PHGG with each meal for 12 months significantly lowered the postprandial plasma glucose (PG), reduced both the fasting and postprandial insulin (IRI) and triacylglycerol (TG) levels (p = 0.05). Low-density lipoprotein (LDL) was lower, whereas high-density lipoprotein (HDL) level was significantly increased (p < 0.01). Plasma leptin, high-sensitive C-reactive protein (hs-CRP) and fasting glucagon like peptide (GLP-1) were also lowered. In fact, 3 out of 6 glucose intolerant subjects turned out to be normal glucose tolerant after only 3 months of PHGG supplementation. Therefore, this preliminary study revealed that inclusion of PHGG in diets potentially impact on metabolic health profiles by affecting circulating metabolites that are responsible for glycaemia, hyperinsulinaemia and hyperlipidaemia factors.

Irisin is more strongly predicted by muscle oxidative potential than adiposity in non-diabetic men.

Numerous controversies surround the peptide hormone irisin. Although implicated as a myokine promoting the browning of adipose tissue in rodents, its roles in humans remain unclear. Contradictory results have also been found with respect to the relationships between adiposity or metabolic health and plasma irisin levels in humans. We investigated the relationship between irisin levels and body composition (hydrostatic weighing), insulin sensitivity (hyperinsulinemic-euglycemic clamp), fitness level (ergocycle VO2max) and skeletal muscle metabolic profile in 53 men (aged 34-53 years) from four groups: sedentary non-obese controls (body mass index [BMI] <25 kg/m(2)), sedentary obese (BMI >30 kg/m(2)), sedentary obese glucose-intolerant, and non-obese highly trained endurance active. Baseline plasma irisin levels were significantly different between groups, being lowest in trained men (140.6 ± 38.2 ng/mL) and highest in metabolically deteriorated glucose-intolerant subjects (204.0 ± 50.5 ng/mL; ANOVA p = 0.01). Including all subjects, irisin levels were positively associated with adiposity (e.g. fat mass, r = 0.430, p < 0.01) and negatively associated with fitness (r = -0.369, p < 0.01), insulin sensitivity (M/I, r = -0.355, p < 0.01) and muscle citrate synthase (CS) activity (r = -0.482, p < 0.01). Most correlations lost statistical significance when excluding active individuals, except for insulin resistance (r = -0.413, p < 0.01) and CS (r = -0.462, p < 0.01). Multiple regression analyses reveal CS as the strongest independent predictor of irisin levels (r(2) range 0.214 to 0.237). We conclude that muscle oxidative potential is an important factor linked to circulating irisin levels.

Chronic stress aggravates glucose intolerance in leptin receptor-deficient (db/db) mice.

Genetic predisposition and environmental challenges interact to determine individual vulnerability to obesity and type 2 diabetes. We previously established a mouse model of chronic subordination stress-induced hyperphagia, obesity, metabolic like-syndrome and insulin resistance in the presence of a high-fat diet. However, it remains to be established if social stress could also aggravate glucose intolerance in subjects genetically predisposed to develop obesity and type 2 diabetes. To answer this question, we subjected genetically obese mice due to deficiency of the leptin receptor (db/db strain) to chronic subordination stress. Over five weeks, subordination stress in db/db mice led to persistent hyperphagia, hyperglycemia and exacerbated glucose intolerance altogether suggestive of an aggravated disorder when compared to controls. On the contrary, body weight and fat mass were similarly affected in stressed and control mice likely due to the hyperactivity shown by subordinate mice. Stressed db/db mice also showed increased plasma inflammatory markers. Altogether our results suggest that chronic stress can aggravate glucose intolerance but not obesity in genetically predisposed subjects on the basis of a disrupted leptin circuitry.

Skeletal muscle ceramide species in men with abdominal obesity.

Obesity is a risk factor for diabetes and its consequences, including accelerated ageing and mortality. The underlying factor could be accumulation of certain lipid moieties, such as ceramides (CER) and diacylgycerol (DAG) within muscle tissue, which are known to promote insulin resistance (IR), induce inflammation and oxidative injury, ultimately altering muscle function. First, to study the relationship between body composition and age (independent variables) with skeletal muscle accumulation of lipid species, oxidative injury and strength. Second, to analyze the relationship between muscle tissue metabolites and insulin resistance, inflammation and lymphocyte telomere length, the latter as an indicator of ageing. The sample included 56 healthy sedentary males, scheduled for inguinal hernia surgery, aged 27 to 80 y. Each individual was subject to anthropometric measurements, body composition assessment through radiologic densitometry (DEXA), measurement of handgrip and quadriceps strength, serum biochemical parameters (lipoproteins, creatinine, high sensitivity C reactive protein [hsCRP], fasting and post glucose insulin and glucose concentrations for calculation of IR through the Matsuda and HOMA-IR indexes), and extraction of peripheral leukocytes for measurement of telomere length. During the surgical procedure, a sample of muscle tissue was obtained (anterior abdominal oblique) in order to measure CER and DAG (and sub species according to chain length and saturation) by mass spectrometry, 4 hydroxy-2-nonenal adducts (4-HNE) using electron microscopy immunohistochemistry, and carboxymethyl-lisine (CML) by immunohistochemistry, the latter as indicators of oxidative stress (OS). Body mass index (BMI) of twenty six individuals was > 25 k/m2, while BMI of 7 was > 30 k/m2. Overweight/obese individuals, did not exhibit differences in skeletal muscle lipid metabolites, however total CER and specific long chain CER sub-species (20 and 22 carbon) increased significantly among individuals with a central fat distribution (n = 14) as well as in glucose intolerant subjects (n =23). A negative association was found between mononuclear leukocyte telomere length and 20 and 22 carbon CER (rho = - 0.4 and -0.5 0 p < 0.05). Muscle strength was not associated with any of the measured muscle metabolites or markers of OS. A multiple regression analysis accepted central abdominal fat and telomere length as significant predictors of CER (R2 = 0.28). An association was found between accumulation of specific ceramide species in muscle tissue and abdominal obesity, glucose intolerance and shortening of leukocyte telomeres, although not with muscle oxidative injury or dysfunction.

Plasma irisin is associated with insulin resistance in men (854.4)

The hormone irisin has been described as increasing energy expenditure and improving glucose tolerance in mice, yet its potential role in humans remains controversial. Objective: We describe the association between circulating irisin and insulin resistance in men with wide‐ranging fitness levels and metabolic health. Methods: Fifty‐two men aged 34‐53 yrs from 4 groups were compared: sedentary non‐obese controls (BMI&lt;25 kg/m2), sedentary obese (BMI&gt;30 kg/m2), sedentary obese glucose intolerant, and non‐obese highly trained endurance active. All participants were evaluated for fitness (VO2max), anthropometric profile, circulating metabolic profile, insulin resistance (hyperinsulinemic‐euglycemic clamp), and baseline plasma irisin levels (EIA, Phoenix Pharamaceuticals, Inc.). Results: Baseline plasma irisin levels were significantly different between groups (ANOVA p=0.01), being lowest in trained men (1406±382 ng/mL) and highest in metabolically deteriorated glucose intolerant subjects (2040±505 ng/mL). Including all subjects, irisin levels were positively associated with percent body fat (r=0.445, p&lt;0.01), and negatively associated with fitness (r=‐0.369, p&lt;0.01) and insulin sensitivity (M/I, r=‐0.355, p&lt;0.01). The strength of these associations was reduced and lost statistical significance when excluding the active individuals, except for that with insulin resistance, which was slightly increased (r=‐0.413, p&lt;0.01). Conclusion: Plasma irisin levels are associated with decreased insulin sensitivity in men, but the association appears to be influenced by training status.Grant Funding Source: Supported by the CIHR and CRIUCPQ.

Lean mass inversely predicts plasma glucose levels after oral glucose load independent of insulin secretion or insulin sensitivity in glucose intolerance subjects

Muscle mass inversely relates to 2 hours glucose levels after oral glucose load in non-diabetic subjects. A study in glucose intolerance subjects has never been performed. We conducted this study to determine the relationship between muscle mass and glucose level after oral glucose load in glucose intolerance subjects. Sixty Thai subjects, 44 drug-naïve, newly diagnosed type 2 diabetes mellitus and 16 impaired glucose tolerance were studied. The 180 min 75 g oral glucose tolerance test was performed. Total body fat and lean mass were measured by dual-energy x-ray absorptiometry. Insulin sensitivity was determined by insulin sensitivity index using model of Matsuda & DeFronzo. The 1st-phase and total insulin secretion were determined from glucose tolerance data. Pearson correlation and linear regression were used for the analysis. Lean mass was inversely correlated with area-under-curves of glucose 0-180 min (r =-0.320; p=0.013). The relationship was significant after adjustment with age and body-mass-index (r =-0.350; p=0.007). Area-under-curves of glucose 0-180 min was correlated with height (r =-0.282; p=0.029), fasting glucose (r =0.742; p<0.0001), log area-under-curves of insulin 0-180 min (r =-0.258; p=0.047) and log 1st-phase insulin secretion (r =-0.518; p<0.0001). By multivariate analysis, fasting glucose (standardized β=4.54; p<0.001), log 1st-phase insulin secretion (standardized β=-43.09; p=0.005) and lean mass (standardized β=-0.003; p=0.011) were the significant parameters predicting area-under-curves of glucose 0-180 min. In conclusion, lean mass inversely predicted glucose levels after oral glucose load independent of insulin secretion and insulin sensitivity in glucose intolerance subjects.

Association of VO2 and VCO2 rate variability with serum glucose, insulin, and glucose intolerance

Changes in the cellular metabolism assessed by the variability of oxygen consumption (VO(2) ) and carbon dioxide production (VCO(2) ) as well as the association of serum glucose and insulin to energy spectral density (ESD) of VO(2) and VCO(2) were evaluated. Ten nonglucose intolerant and 10 glucose intolerant subjects, aged 21-70 years, were included. Glucose and insulin concentrations and VO(2) and VCO(2) records were collected every 10 min during 3 h. ESD of VO(2) and VCO(2) was estimated and associated with glucose and insulin concentrations. Statistical significance in glucose levels, insulin, and ESD of VO(2) and VCO(2) among nonglucose intolerant subjects and glucose and insulin among glucose intolerance subjects at postload glucose (PLG) state compared with basal state was found. Moreover, glucose was significantly higher in glucose intolerance subjects than nonglucose intolerant subjects for basal and PLG states. These results show an increment in ESD of VO(2) and VCO(2) at PLG state among nonglucose intolerant subjects and suggest that their measurement may be a key indicator of the variability of cellular metabolic activity and contribute to confirm disturbances in glucose metabolism.

Effects of variation in retinol binding protein 4 gene and adipose specific expression of gestational diabetes in Beijing, China

ObjectiveTo investigate the clinical features of GDM in China and the effects of RBP4 genetic variants, and also to identify RBP4 expression changes in mRNA and protein levels. Research design and methods1595 Chinese pregnant women were included in this study. Four known RBP4 single nucleotide polymorphisms (SNPs) were genotyped in 505 cases and 687 controls. Expression levels of adipose specific RBP4 mRNA and protein were detected in 41 samples of subcutaneous adipose tissue. ResultsThe estimated indices of insulin resistance were gradually increased from NGT, GIGT to GDM. Two single SNPs were associated with GDM (rs3758539 G vs A, OR=1.446, P=0.009; rs3758539 GG vs AG+AA, OR=1.532, P=0.006; rs12265684C vs G, OR=1.296, P=0.038) and a haplotype of 3 common SNPs [G-G-T] was increased in subjects with GDM and GIGT (OR=1.322, 95% CI 1.054–1.659, P=0.016). RBP4 mRNA expression in adipose tissue of GDM patients was significantly increased in comparison to control subjects (1.438±0.187 vs 1.034±0.062, p=0.025). ConclusionThis finding suggests that impaired insulin sensitivity has an early onset in mild gestational intolerance. Two single SNPs were associated with GDM in the case-control study while a haplotype of 3 common SNPs [G-G-T] was increased in glucose intolerance subjects.

Prevalence of components of the metabolic syndrome according to birthweight among overweight and obese children and adolescents

Extremes of birthweight (BW) have been associated with increased rates of metabolic risks. The objective was to study the prevalence of metabolic risks markers among obese and overweight (OW) subjects according to BW. A cross-sectional study was performed in a cohort of 1002 patients (2-18 years, 40.6% male) evaluated for OW or obese subjects in two private clinics. Anthropometrics, fasting lipids, glycemia, and insulin were obtained. Of the subjects, 76.1% were born appropriate for gestational age (AGA), 10.9% small for gestational age (SGA), and 13% large for gestational age (LGA). Children born LGA presented a more severe degree of obesity compared with those born AGA and SGA (p<0.0001). No differences in glycemia, insulin, and lipid levels were detected among the groups. Abnormal glucose was found in 37 subjects: one with type 2 diabetes mellitus (from the previously glucose-intolerant subjects), 10 with glucose intolerance, and 27 with impaired fasting glucose. According to Boney criteria, 6.6% of the patients (6-18 years old) exhibited metabolic syndrome (MS) (69.4% AGA, 12.9% SGA, and 17.7% LGA). Being born LGA represents a higher risk of severe obesity. At this age, the most frequent component of MS was an abnormal lipid profile with low high-density lipoprotein and high triglycerides. Finally, the most frequent finding associated with abnormalities of glucose tolerance was a family history of diabetes. Thus, BW, lipid profile, and family history are mandatory when these patients are evaluated.

Natural history and physiological determinants of changes in glucose tolerance in a non-diabetic population: the RISC Study

The natural history and physiological determinants of glucose intolerance in subjects living in Europe have not been investigated. The aim of this study was to increase our understanding of this area. We analysed the data from a population-based cohort of 1,048 non-diabetic, normotensive men and women (aged 30-60 years) in whom insulin sensitivity was measured by the glucose clamp technique (M/I index; average glucose infusion rate/steady-state insulin concentration) and beta cell function was estimated by mathematical modelling of the oral glucose tolerance test at baseline and 3 years later. Seventy-seven per cent of the participants had normal glucose tolerance (NGT) and 5% were glucose intolerant both at baseline and follow up; glucose tolerance worsened in 13% (progressors) and improved in 6% (regressors). The metabolic phenotype of the latter three groups was similar (higher prevalence of familial diabetes, older age, higher waist-to-hip ratio, higher fasting and 2 h plasma glucose, higher fasting and 2 h plasma insulin, lower insulin sensitivity and reduced beta cell glucose sensitivity with increased absolute insulin secretion). Adjusting for these factors in a logistic model, progression was predicted by insulin resistance (bottom M/I quartile, OR 2.52 [95% CI 1.51-4.21]) and beta cell glucose insensitivity (bottom quartile, OR 2.39 [95% CI 1.6-3.93]) independently of waist-to-hip ratio (OR 1.44 [95% CI 1.13-1.84] for one SD). At follow up, insulin sensitivity and beta cell glucose sensitivity were unchanged in the stable NGT and stable non-NGT groups, worsened in progressors and improved in regressors. Glucose tolerance deteriorates over time in young, healthy Europids. Progressors, regressors and glucose-intolerant participants share a common baseline phenotype. Insulin sensitivity and beta cell glucose sensitivity predict and track changes in glucose tolerance independently of sex, age and obesity.

Circulating osteocalcin is increased in early-stage diabetes

We aimed to examine whether circulating levels of osteocalcin, bone formation marker secreted from osteoblast, are changed in glucose-intolerant subjects without taking glucose lowering agent, because bone metabolism is reportedly related to glucose metabolism in animal and human studies. According to 75g oral glucose tolerance test (75g-OGTT), all subjects (47.6±10.2 years of age; 45 men and 10 women) were divided into three categories: normal glucose tolerance (NGT, n=39), prediabetes (PDM, n=11) that included impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), and diabetes (T2DM, n=5). Serum osteocalcin levels were increased in T2DM as compared to NGT. In all the participants, simple regression analysis model revealed positive correlation of osteocalcin with plasma glucose at 120min, G(120), on 75g-OGTT, negative with both creatinine and Ln(CRP), but not significantly with fasting plasma glucose. Osteocalcin and leptin were independent variables for G(120) (P=0.026 and 0.035, respectively). In multinomial logistic analysis leptin (PDM vs. NGT: P=0.02 Odds ratio (OR) of 1.05, 95% confidence intervals, 1.007–1.084) and osteocalcin (T2DM vs. NGT: P=0.038, OR 10.8, 1.13–102.4) were independently associated. We conclude that circulating osteocalcin and leptin are related to glucose intolerant state.

Differences in islet-enriched miRNAs in healthy and glucose intolerant human subjects

Many microRNAs (miRNAs) are known to be cell-type specific and are implicated in development of diseases. We investigated the global expression pattern of miRNAs in human pancreatic islets compared to liver and skeletal muscle, using bead-based technology and quantitative RT-PCR. In addition to the known islet-specific miR-375, we also found enrichment of miR-127-3p, miR-184, miR-195 and miR-493∗ in the pancreatic islets. The expression of miR-375, miR-127-3p, miR-184 and the liver-enriched miR-122 is positively correlated to insulin biosynthesis, while the expression of miR-127-3p and miR-184 is negatively correlated to glucose-stimulated insulin secretion (GSIS). These correlations were absent in islets of glucose intolerant donors (HbA1c⩾6.1). We suggest that the presence of an islet-specific miRNA network, which consists of at least miR-375, miR-127-3p and miR-184, potentially involved in insulin secretion. Our results provide new insight into miRNA-mediated regulation of insulin secretion in healthy and glucose intolerant subjects.

The effects of physical activity, body mass index (BMI) and waist circumference (WC) on glucose intolerance in older people: A nationwide study from Taiwan

We investigated the gender-specific effects of physical activity, BMI and WC on glucose intolerance in an elderly Taiwanese population ( n = 1344) aged 65 and above, who participated in the Elderly Nutrition and Health Survey in Taiwan in 1999–2000. In this cross-sectional study, physical activity was assessed using the Modified Baecke Questionnaire for Older Adults (MBQOA). Categories of physical activity level were defined by tertiles of MBQOA scores. Glucose intolerance in subjects not previously diagnosed with diabetes was categorized according to 2003 American Diabetes Association criteria. After adjustment for potential confounders, physical activity was significantly inversely associated with the presence of undiagnosed type 2 diabetes and impaired fasting glucose (IFG) in older women. In older men, the association was less clear. BMI and WC were significantly positively associated with the presence of undiagnosed diabetes in men and were significantly associated with IFG in both sexes. In older women, undiagnosed diabetes was strongly associated with increased WC, but not with BMI. Our findings highlight that older women with low physical activity or high WC, and older men with high BMI or WC are important target populations for interventions to prevent glucose intolerance.

Dissociation between Skeletal Muscle Inhibitor-κB Kinase/Nuclear Factor-κB Pathway Activity and Insulin Sensitivity in Nondiabetic Twins

Several studies suggest a link between increased activity of the inflammatory inhibitor-kappaB kinase/nuclear factor-kappaB (IKK/NF-kappaB) pathway in skeletal muscle and insulin resistance. We aimed to study the regulation of skeletal muscle IKK/NF-kappaB pathway activity as well as the association with glucose metabolism and skeletal muscle insulin signaling. The study population included a metabolically well-characterized cohort of young and elderly predominantly nondiabetic twins (n = 181). Inhibitor-kappaBbeta (IkappaBbeta) protein levels are negatively associated with IKK/NF-kappaB pathway activity and were used to evaluate pathway activity with p65 levels included as loading control. This indirect measure for IKK/NF-kappaB pathway activity was validated by a p65 binding assay. Evaluating the effects of heritability, age, sex, obesity, aerobic capacity, and several hormonal factors (eg insulin and TNF-alpha), only sex and age were significant predictors of IkappaBbeta to p65 ratio (28% decreased ratio in the elderly, P < 0.01, and 49% increased in males P < 0.01). IkappaBbeta to p65 ratio was unrelated to peripheral insulin sensitivity (P = 0.51) and in accordance with this also unrelated to proximal insulin signaling (P = 0.81). Although no association was seen with plasma glucose after oral glucose challenge, there was a tendency for lower IkappaBbeta to p65 ratio (adjusted for age and sex) in subjects with impaired as opposed to normal glucose tolerance (P = 0.055). Altogether the subtle elevated IKK/NF-kappaB pathway activity seen in glucose-intolerant subjects suggests that IKK/NF-kappaB pathway activation may be secondary to impaired glucose tolerance and that skeletal muscle IKK/NF-kappaB pathway activity is unlikely to play any major role in the control of skeletal muscle insulin action in nondiabetic subjects.

Circulating soluble CD36 is associated with glucose metabolism and interleukin-6 in glucose-intolerant men

Recently, soluble CD36 (sCD36) levels were reported to be elevated in type 2 diabetes, and to be tightly correlated with insulin resistance. Our aim was to obtain further insight into the relationship between insulin sensitivity, low-grade inflammation and sCD36. We studied glucose-tolerant (n=90) and glucose-intolerant (n=57) moderately obese men. Insulin sensitivity was measured by the frequent sample intravenous glucose tolerance test, and sCD36 by an in-house ELISA assay. In glucose-intolerant subjects, sCD36 was negatively associated with insulin sensitivity and positively with interleukin-6 (IL-6), fasting glucose, fasting triglycerides, fat-free mass and platelet count. On multiple linear regression analyses, insulin sensitivity contributed 22% of sCD36 variance, independent of age, body mass index (BMI) and IL-6, in glucose-intolerant subjects. The level of sCD36 in subjects with glycosylated haemoglobin (HbA1C) above the mean was higher than in those with HbA1C values below the mean. Insulin sensitivity is a predictor of sCD36 in men with impaired glucose tolerance. IL-6 is related to sCD36 but does not predict sCD36 independent of insulin sensitivity and BMI.

Subclinical inflammation/oxidation as revealed by altered gene expression profiles in subjects with impaired glucose tolerance and Type 2 diabetes patients

Although subclinical inflammation and oxidative stress are implicated in the aetiology of diabetes, there are hardly any studies in prediabetes. Therefore, we made an attempt to study the gene expression pattern of certain inflammatory/oxidative genes using lymphocytes from Type 2 diabetic patients, impaired glucose tolerance (IGT), and normal glucose tolerance (NGT) subjects. Compared to NGT group, interleukin-6, tumor necrosis factor-alpha (TNF-alpha), p(22)Phox NADPH oxidase, and thioredoxin interacting protein (TXNIP) mRNA levels were higher and suppressor of cytokine signaling (SOCS-3) mRNA was lower in subjects with IGT and diabetes. The mean (+/-SE) levels of thiobarbituric acid reactive substances and protein carbonyl content were also elevated in glucose intolerant subjects. In multiple linear regression analysis, TXNIP and TNF-alpha showed a significant association with HbA1c even after adjusting for TBARS and PCO (TXNIP: beta = 1.70, P < 0.01; TNF-alpha: beta = 1.86, P < 0.01). Increased subclinical inflammation/oxidation is seen in Asian Indians with not only Type 2 diabetes but also IGT.

The role of osteocalcin in the connection of bone and glucose metabolism in humans

The lack of osteoblast derived osteocalcin in mice causes reduced pancreatic beta-cell proliferation, decreased expression of insulin gene and adiponectin gene in adipocytes as well. The relationship between insulin sensitivity, osteocalcin and bone state in 45 healthy (20 females, 25 males) and 92 glucose intolerant (51 females, 41 males) subjects was examined. Body composition, bone density, markers of bone resorption and formation as well as glucose uptake (M value for insulin sensitivity) measured by hyperinsulinemic normoglycemic clamp were determined separately in males and females. Osteocalcin levels were similar in the two genders, however, glucose intolerant men had lower osteocalcin levels than healthy men (24.5+/-11 vs. 18.1+/-9 ng/ml, p < 0.05). In the healthy group, we found positive correlation between osteocalcin and muscle M values (females: r = +0.319, p < 0.05, males: r = 0.481, p < 0.01), although this relationship disappeared in the glucose intolerant groups. Osteocalcin did not show correlation with adiponectin level in any of the genders. Based on a multivariate regression analysis, in all females significant independent predictors of osteocalcin level were fasting blood glucose, whole and lean body mass glucose uptake, metabolic clearance rate, estradiol and LDL-cholesterol levels (determined 92% of its value), while in all men these were serum calcium, OGTT glucose area under the curve, free fatty acid levels, insulogenic index, HOMA-R and waist/hip ratio (determined 95% of its value). The BMU index characterizing bone resorption/formation correlated significantly with the M values only in women. This study confirmed the relationship between insulin sensitivity and osteocalcin in healthy human population, although basic difference was found between the two genders which was not related to osteocalcin.