Indirect Effects of Body Mass Index Growth on Glucose Dysregulation via Inflammation: Causal Moderated Mediation Analysis.

OBJECTIVE: No existing studies have examined the mediating role of chronic inflammation between obesity and dysregulated glucose homeostasis in adolescent samples. This study evaluated whether C-reactive protein (CRP), an inflammation biomarker, mediated the effects of growth (annual increase) in body mass index (BMI) on glycated hemoglobin (HbA1c). METHODS: BMI and biomarker data were used from wave I to wave IV of the National Longitudinal Study of Adolescent to Adult Health (Add Health study; 4,545 adolescents; mean age = 14.9 years; 55.7% female) with valid CRP data. A causal moderated mediation analysis evaluated the direct and indirect effects of BMI slope on HbA1c via CRP across gender, with demographic and clinical characteristics as model covariates. RESULTS: The participants displayed a linear BMI growth of 0.53-0.58 kg/m2/year throughout adolescence, with substantial interindividual variation. The BMI slope showed positive direct and indirect effects on HbA1c via CRP across gender, and there was a significant exposure-mediator interaction effect. A standardized increase in the BMI slope raised the probability of an abnormal HbA1c value by 6.0-8.5% in participants with various profiles. The total natural indirect effect accounted for 13.3-15.9% of the total effect in males and 21.2-22.7% in females. CONCLUSIONS: The findings provide support for the inflammation mechanism in the effects of adiposity on glucose homeostasis. In adolescents, excess BMI growth was linked with a higher risk of glucose dysregulation either directly or indirectly via chronic inflammation.

An Integrated View of Immunometabolism.

The worldwide obesity epidemic has emerged as a major cause of insulin resistance and Type 2 diabetes. Chronic tissue inflammation is a well-recognized feature of obesity, and the field of immunometabolism has witnessed many advances in recent years. Here, we review the major features of our current understanding with respect to chronic obesity-related inflammation in metabolic tissues and focus on how these inflammatory changes affect insulin sensitivity, insulin secretion, food intake, and glucose homeostasis. There is a growing appreciation of the varied and sometimes integrated crosstalk between cells within a tissue (intraorgan) and tissues within an organism (interorgan) that supports inflammation in the context of metabolic dysregulation. Understanding these pathways and modes of communication has implications for translational studies. We also briefly summarize the state of this field with respect to potential current and developing therapeutics.

Successful treatment of type B insulin resistance with mixed connective tissue disease by pulse glucocorticoids and cyclophosphamide.

Type B insulin resistance syndrome is a very rare condition caused by autoantibodies against the insulin receptor. We report the successful treatment of a patient with refractory type B insulin resistance with pulse glucocorticoids and cyclophosphamide. The medical record of a patient with type B insulin resistance was reviewed. A 36-year-old Chinese woman presented with menopause, weight loss and refractory hyperglycemia for 3 months, which could not be controlled by up to 972 of insulin units per day. Mixed connective tissue disease was diagnosed with high titers of antinuclear antibody, ribonucleoprotein antibody and interstitial lung disease. Type B insulin resistance was diagnosed with positive immunoprecipitation assay of anti-insulin-receptor antibodies in serum. We started one cycle of pulse methylprednisolone (1,000 mg/day for 3 days) then tapered to prednisone 1 mg/kg/day, and cyclophosphamide 0.4 g/week was added on. Three weeks after pulse glucocorticoid therapy, fasting glucose returned to 4.4 mmol/L. Fasting insulin decreased from 647.27 to 12.95 uIU/mL 6 weeks later. The patient had gained 15 kg during 20 months of uneventful following up, and glycated hemoglobin decreased from 10.1 to 5.1%.In this patient with type B insulin resistance, a combination of pulse glucocorticoids and cyclophosphamide was successful in inducing a complete remission. Close cooperation between endocrinologists and rheumatologists will ensure an individualized regimen for this rare condition.

Prognostic Classification Factors Associated With Development of Multiple Autoantibodies, Dysglycemia, and Type 1 Diabetes-A Recursive Partitioning Analysis.

OBJECTIVE: To define prognostic classification factors associated with the progression from single to multiple autoantibodies, multiple autoantibodies to dysglycemia, and dysglycemia to type 1 diabetes onset in relatives of individuals with type 1 diabetes. RESEARCH DESIGN AND METHODS: Three distinct cohorts of subjects from the Type 1 Diabetes TrialNet Pathway to Prevention Study were investigated separately. A recursive partitioning analysis (RPA) was used to determine the risk classes. Clinical characteristics, including genotype, antibody titers, and metabolic markers were analyzed. RESULTS: Age and GAD65 autoantibody (GAD65Ab) titers defined three risk classes for progression from single to multiple autoantibodies. The 5-year risk was 11% for those subjects >16 years of age with low GAD65Ab titers, 29% for those ≤16 years of age with low GAD65Ab titers, and 45% for those subjects with high GAD65Ab titers regardless of age. Progression to dysglycemia was associated with islet antigen 2 Ab titers, and 2-h glucose and fasting C-peptide levels. The 5-year risk is 28%, 39%, and 51% for respective risk classes defined by the three predictors. Progression to type 1 diabetes was associated with the number of positive autoantibodies, peak C-peptide level, HbA1c level, and age. Four risk classes defined by RPA had a 5-year risk of 9%, 33%, 62%, and 80%, respectively. CONCLUSIONS: The use of RPA offered a new classification approach that could predict the timing of transitions from one preclinical stage to the next in the development of type 1 diabetes. Using these RPA classes, new prevention techniques can be tailored based on the individual prognostic risk characteristics at different preclinical stages.

Glucose Metabolism Disorders, HIV and Antiretroviral Therapy among Tanzanian Adults.

INTRODUCTION: Millions of HIV-infected Africans are living longer due to long-term antiretroviral therapy (ART), yet little is known about glucose metabolism disorders in this group. We aimed to compare the prevalence of glucose metabolism disorders among HIV-infected adults on long-term ART to ART-naïve adults and HIV-negative controls, hypothesizing that the odds of glucose metabolism disorders would be 2-fold greater even after adjusting for possible confounders. METHODS: In this cross-sectional study conducted between October 2012 and April 2013, consecutive adults (>18 years) attending an HIV clinic in Tanzania were enrolled in 3 groups: 153 HIV-negative controls, 151 HIV-infected, ART-naïve, and 150 HIV-infected on ART for ≥ 2 years. The primary outcome was the prevalence of glucose metabolism disorders as determined by oral glucose tolerance testing. We compared glucose metabolism disorder prevalence between each HIV group vs. the control group by Fisher's exact test and used multivariable logistic regression to determine factors associated with glucose metabolism disorders. RESULTS: HIV-infected adults on ART had a higher prevalence of glucose metabolism disorders (49/150 (32.7%) vs.11/153 (7.2%), p<0.001) and frank diabetes mellitus (27/150 (18.0%) vs. 8/153 (5.2%), p = 0.001) than HIV-negative adults, which remained highly significant even after adjusting for age, gender, adiposity and socioeconomic status (OR = 5.72 (2.78-11.77), p<0.001). Glucose metabolism disorders were significantly associated with higher CD4+ T-cell counts. Awareness of diabetes mellitus was <25%. CONCLUSIONS: HIV-infected adults on long-term ART had 5-fold greater odds of glucose metabolism disorders than HIV-negative controls but were rarely aware of their diagnosis. Intensive glucose metabolism disorder screening and education are needed in HIV clinics in sub-Saharan Africa. Further research should determine how glucose metabolism disorders might be related to immune reconstitution.

Chronic inflammation exacerbates glucose metabolism disorders in C57BL/6J mice fed with high-fat diet.

Inflammatory stress is closely related to metabolic disease and insulin resistance. The precise cellular mechanism linking obesity and diabetes is largely unknown, but about 14-20% of obese individuals develop diabetes. In this study, we investigated whether chronic inflammation exacerbated glucose metabolism disorder by impairing ß cell function in high-fat diet (HFD)-fed C57BL/6J mice. We used s.c. casein injection to induce chronic inflammation in HFD-fed C57BL/6J mice; 14 weeks on a HFD resulted in weight gain, hyperlipidemia, and low insulin sensitivity in these mice which nevertheless had normal blood glucose and serum inflammatory cytokines levels. Casein injection in the background of HFD elevated serum tumor necrosis factor α (TNFα) and serum amyloid A levels and increased TNFα and MCP1 expression in the adipose tissue, liver, and muscle of HFD-fed mice. Chronic inflammation induced by casein injection further decreased insulin sensitivity and insulin signaling, resulting in insulin deficiency and hyperglycemia in these mice. Islet mass and insulin content were markedly increased in HFD mice. However, in contrast with HFD-fed alone, chronic inflammation in HFD-fed mice decreased both islet mass and insulin content, reduced the genetic expression of insulin synthesis and secretion, and increased ß cell apoptosis. We conclude that chronic inflammation exacerbated glucose metabolism disorders by impairing ß cell function in HFD-fed C57BL/6J mice, suggesting that this mechanism may operate in obese individuals with chronic inflammation, making them prone to hyperglycemia.

Lymphocyte-suppressing and systemic anti-inflammatory effects of high-dose metformin in simvastatin-treated patients with impaired fasting glucose.

OBJECTIVE: No previous study has investigated whether metformin produces any effect on lymphocyte secretory function in patients with glucose metabolism abnormalities. METHODS: Sixty-two subjects with impaired fasting glucose (IFG) treated for at least 3 months with simvastatin were allocated into one of two groups receiving, respectively, metformin (3 g daily) or placebo for the following 90 days. Plasma lipids, glucose homeostasis markers, plasma C-reactive protein and intercellular adhesion molecule-1 levels, as well as lymphocyte release of proinflammatory cytokines were determined before randomization and at the end of the treatment. RESULTS: Fifty-eight patients completed the study. Metformin, but not placebo, administered to simvastatin-treated IFG subjects reduced plasma levels of C-reactive protein, soluble intercellular adhesion molecule-1, as well as lymphocyte release of interleukin-2, interferon-γ and tumor necrosis factor-α, which was accompanied by the improvement in insulin sensitivity and a reduction in free fatty acid levels. CONCLUSIONS: The obtained results indicate that metformin potentiates lymphocyte-suppressing and systemic anti-inflammatory effects of simvastatin in subjects with IFG. These effects of statin-metformin combination therapy may play a role in the prevention and treatment of atherosclerosis and its complications in patients with early glucose metabolism abnormalities.

The association of baseline adipocytokine levels with glycemic progression in nondiabetic Korean adults in 4 years of follow-up.

AIMS: Low-grade inflammation and lipotoxicity contribute to insulin resistance and islet secretory dysfunction that lead to insulin deficiency. We analyzed the associations of several adipocytokines measured at baseline with glycemic progression in non-diabetic Korean subjects after a 4-year follow-up. METHODS: In 479 non-diabetic Korean subjects who underwent medical screening in 2003, serum tumor necrosis factor (TNF)-α, interleukin (IL)-6, retinol-binding protein (RBP)-4, monocyte chemoattractant protein (MCP)-1, visfatin and fatty acid-binding protein (FABP)-4 were measured at baseline. After 4 years, changes in glycemia were assessed. RESULTS: Among the subjects, 79.2% maintained their baseline glycemic status, 14.6% progressed to worse glycemic status (impaired fasting glucose (IFG) to diabetes, normoglycemia to IFG or normoglycemia to diabetes) and 5.8% regressed to normoglycemia after 4 years. Baseline TNF-α and FABP4 showed the highest values in the progression group. In the logistic regression analyses with glycemic progression as the dependent variable and TNF-α and FABP4 as independent variables in separate models, TNF-α and FABP4 individually predicted glycemic progression after adjustment for confounding variables. When both adipocytokines were included in the same model, only FABP4 significantly predicted glycemic progression after 4 years. CONCLUSIONS: TNF-α and FABP4 were significant predictors for glycemic progression in 4 years, with FABP4 being the stronger predictor.

Effects of 90-day hypolipidemic treatment on insulin resistance, adipokines and proinflammatory cytokines in patients with mixed hyperlipidemia and impaired fasting glucose.

OBJECTIVE: Concerns regarding worsening insulin sensitivity associated with statin treatment have recently emerged. Therefore the aim of this study was to assess and compare the effects of 90-day monotherapies with fenofibrate and atorvastatin, as well as combined therapy, on fasting plasma glucose, insulin resistance index, adipokines (leptin, resistin, adiponectin) and levels of proinflammatory cytokines (TNF-α, IL-6) in patients with impaired fasting glucose (IFG) and mixed hyperlipidemia. MATERIALS AND METHODS: 67 patients were randomly assigned to four treatment arms: monotherapy with atorvastatin, monotherapy with fenofibrate, combined therapy (fenofibrate and torvastatin) or therapeutic lifestyle change. The study lasted for 90 days. All participants received counseling regarding proper diet and physical activity. RESULTS: Compared to the control subjects, prediabetic patients exhibited elevated plasma levels of leptin, resistin, TNF-α and IL-6, and a lower plasma level of adiponectin. All therapeutic interventions resulted in significant alterations in the lipid profile. Insulin resistance index (HOMA-IR) was reduced after treatment with fenofibrate. The effect of atorvastatin on insulin resistance was comparable to therapeutic lifestyle change alone. Therapy with hypolipidemic drugs caused increases in adiponectin levels and decreases in leptin and resistin. An additive effect of the combined treatment on plasma IL-6 level was also observed. CONCLUSIONS: Fenofibrate-based treatment was associated with improved insulin sensitivity. Atorvastatin did not cause a deterioration in insulin sensitivity. Hypolipidemic therapies resulted in significant changes in the proinflammatory cytokine network as well as in adipokine levels. At the end of the study the measured parameters nearly resembled those of the healthy subjects.

A diet high in fatty fish, bilberries and wholegrain products improves markers of endothelial function and inflammation in individuals with impaired glucose metabolism in a randomised controlled trial: the Sysdimet study.

AIMS/HYPOTHESIS: Low-grade inflammation and endothelial dysfunction may play a role in the pathogenesis of type 2 diabetes and cardiovascular disease. We evaluated whether a diet high in fatty fish, bilberries and wholegrain products (Healthy Diet) improves biomarkers reflecting inflammation and endothelial dysfunction in individuals with impaired glucose metabolism. METHODS: We recruited individuals with impaired glucose metabolism and features of the metabolic syndrome into a 12 week, parallel design, dietary intervention trial conducted at the Department of Clinical Nutrition, University of Eastern Finland (Kuopio, Finland). Randomisation was performed by matching according to sex and medians of age, BMI and fasting plasma glucose of the study population at screening. The primary endpoint in the present study was the change in plasma inflammatory markers and the measurements were performed blinded to group assignment. High-sensitivity (hs) C-reactive protein (CRP) and E-selectin responses were also analysed separately in participants not using statins (n = 76). RESULTS: Altogether, 131 individuals were assigned to either the Healthy Diet (n = 44), a whole-grain-enriched diet (WGED) (n = 42) or a control (n = 45) diet, and 104 participants (mean ± SD: age 59 ± 7 years; BMI 31.1 ± 3.5 kg/m(2)) who had completed the study, were analysed (Healthy Diet n = 36, WGED n = 34 and control diet n = 34). Plasma E-selectin decreased only in the Healthy Diet group. This occurred in all group participants (p < 0.05) and also after excluding participants using statins (p < 0.05). Plasma hsCRP levels decreased in the Healthy Diet (median -17%, p < 0.05) and WGED (median -27%, p < 0.01) groups in participants not using statins. Controlling for confounding factors, including BMI or insulin sensitivity, did not alter the results. A greater increase in plasma concentration of very-long-chain n-3 fatty acids and in the intake of fibre during the study was associated with a greater decrease in plasma E-selectin (p < 0.05). The intake of test breads consumed during the Healthy Diet and WGED interventions was inversely associated with the change in hsCRP levels (p < 0.001). CONCLUSIONS/INTERPRETATION: Our results suggest that the combined effect of fatty fish, bilberries and wholegrain products may improve endothelial dysfunction and inflammation in overweight and obese individuals at high risk of developing diabetes.

Marginal mass islet transplantation with autologous mesenchymal stem cells promotes long-term islet allograft survival and sustained normoglycemia.

Allogeneic islet transplantation is an option to treat diabetes however there are obstacles that are limiting its clinical use. We have examined whether mesenchymal stem cells (MSC) improve islet graft survival and whether such therapy allows for better graft acceptance with reduced requirement for immunosuppression. In vitro-expanded syngeneic bone marrow-derived MSC were co-transplanted with islets into omental pouch in a rat model of streptozotocin-induced diabetes. Marginal mass syngeneic islet transplantation into the omentum with MSC promoted sustained normoglycemia. Interestingly, allogeneic islets +MSC, but not islets alone, with short-term use of immunosuppression enhanced long-term islet graft survival, insulin expression in the grafts and induced normal serum insulin levels and normoglycemia. T cells from recipients transplanted with allogeneic islets +MSC produced low levels of IFN-gamma and TNF-alpha upon ex-vivo activation, and this transplantation protocol promoted the generation of IL-10-secreting CD4(+) T cells. These data encourage further preclinical and eventually, clinical MSC-based islet transplantation to improve the outcome of allogeneic islet transplantation in the treatment of diabetes.

Influence of HCV infection on insulin-like growth factor 1 and proinflammatory cytokines: association with risk for growth hormone resistance development.

Communications between the endocrine, immune systems and the liver have been postulated. The liver is the central organ in growth hormone/insulin-like growth factor (GH-IGF) axis. Infection with hepatitis C virus (HCV) can lead to liver problems. Although proinflammatory cytokines are an integral part of inflammation in chronic liver diseases, their involvement in mediating hepatic GH resistance during HCV infection remains to be elucidated. To address this issue, our study aimed at evaluating the influence of HCV infection on serum profile of IGF-1, TNF-alpha and IL-6 to assess their possible relation to hepatic dysfunction and GH resistance development. Twenty-five chronic HCV patients were studied together with 15 healthy control subjects. Serum concentration of IGF-1, TNF-alpha and IL-6 was determined by ELISA. HCV viral load was assessed by Real-time polymerase chain reaction using TaqMan probe technology. Basal serum GH levels were determined by a chemiluminescence assay and serum aminotransferases' activities were also measured. TNF-alpha and IL-6 demonstrated higher serum levels, while IGF-1 levels were significantly lower in HCV patients compared to healthy controls. A statistically significant positive correlation was observed between GH and IL-6 levels (P<0.05), a similar trend was found between GH levels, GH/IGF-1 ratio and AST/ALT ratio (P<0.01, P<0.01, respectively). A significant negative correlation was observed between HCV viral load and GH levels (P<0.05). The progressive increase in HCV viral load matches the decrease in circulating IGF-1 levels but without reaching statistical significance. We conclude that the GH insensitivity could be induced by HCV infection and mediated by proinflammatory cytokines through their possible role in blunting the hepatic response to GH. This crosstalk between proinflammatory cytokines and GH-IGF-1 axis could be responsible for triggering impaired glucose metabolism and diabetes later on in chronic HCV infection.