Improving insulin sensitivity, liver steatosis and fibrosis in type 2 diabetes by a food-based digital education-assisted lifestyle intervention program: a feasibility study.

PURPOSE: Recent trials demonstrated remission of type 2 diabetes and non-alcoholic fatty liver disease (NAFLD) following formula diet-induced weight loss. To improve the outreach for populations in need, many mobile health apps targeting weight loss have been developed with limited scientific evaluation of these apps. The present feasibility study investigated the effects of a novel approach incorporating a regular 'whole food-based' low-calorie diet combined with app-based digital education and behavioral change program on glucose metabolism and disease management. METHODS: Twenty-four individuals with type 2 diabetes followed this approach supported by weekly coaching calls for 12 weeks. Phenotyping included bioimpedance analysis, mixed-meal tolerance test, magnetic resonance spectroscopy and transient elastography for assessing liver fat content and liver stiffness. RESULTS: Over 12 weeks, participants reduced their body weight by 9% (97 ± 13 to 88 ± 12 kg), body mass index (BMI; 33 ± 5 to 29 ± 4 kg/m2), total fat mass (31 ± 10 to 27 ± 10%) (all p < 0.01) and liver fat by 50% alongside with decreased liver stiffness. Target HbA1c (< 6.5%) was achieved by 38% and resolution of NAFLD (liver fat content < 5.6%) was observed in 30% of the participants. CONCLUSION: This novel approach combining digital education with a low-calorie diet results in effective improvements of body weight, glycemic control and NAFLD and could complement existing care for patients with type 2 diabetes. TRIAL REGISTRATION: NCT04509245.

Effects of resveratrol supplementation on liver fat content in overweight and insulin-resistant subjects: A randomized, double-blind, placebo-controlled clinical trial.

We performed the largest randomized, placebo-controlled clinical trial to date (N = 112, 12-week intervention) to investigate the effects and safety of resveratrol supplementation on liver fat content and cardiometabolic risk parameters in overweight and obese and insulin-resistant subjects. At baseline the variability in liver fat content was very large, ranging from 0.09% to 37.55% (median, 7.12%; interquartile range, 3.85%-12.94%). Mean (SD) liver fat content was 9.22 (6.85) % in the placebo group and 9.91 (7.76) % in the resveratrol group. During the study liver fat content decreased in the placebo group (-0.7%) but not in the resveratrol group (-0.03%) (differences between groups: P = .018 for the intention-to-treat [ITT] population; N = 54, resveratrol, N = 54, placebo and P = .0077 for the per protocol [PP] population). No effects of resveratrol supplementation on cardiometabolic risk parameters were observed. Resveratrol supplementation was well tolerated and safe. In conclusion, these data suggest that resveratrol supplementation is safe and that it does not considerably impact liver fat content or cardiometabolic risk parameters in humans.

Non-alcoholic fatty liver disease and impaired proinsulin conversion as newly identified predictors of the long-term non-response to a lifestyle intervention for diabetes prevention: results from the TULIP study.

AIMS/HYPOTHESIS: Lifestyle intervention is effective to prevent type 2 diabetes. However, a considerable long-term non-response occurs to a standard lifestyle intervention. We investigated which risk phenotypes at baseline and their changes during the lifestyle intervention predict long-term glycaemic non-response to the intervention. METHODS: Of 300 participants at high risk for type 2 diabetes who participated in a 24 month lifestyle intervention with diet modification and increased physical activity, 190 participants could be re-examined after 8.7 ± 1.6 years. All individuals underwent a five-point 75 g OGTT and measurements of body fat compartments and liver fat content with MRI and spectroscopy at baseline, 9 and 24 months during the lifestyle intervention, and at long-term follow-up. Fasting proinsulin to insulin conversion (PI/I ratio) and insulin sensitivity and secretion were calculated from the OGTT. Non-response to lifestyle intervention was defined as no decrease in glycaemia, i.e. no decrease in AUC for glucose at 0-120 min during OGTT (AUCglucose0-120 min). RESULTS: Before the lifestyle intervention, 56% of participants had normal glucose regulation and 44% individuals had impaired fasting glucose and/or impaired glucose tolerance. At long-term follow-up, 11% had developed diabetes. Multivariable regression analysis with adjustment for age, sex, BMI and change in BMI during the lifestyle intervention revealed that baseline insulin secretion and insulin sensitivity, as well as change in insulin sensitivity during the lifestyle intervention, predicted long-term glycaemic control after 9 years. In addition, increased hepatic lipid content as well as impaired fasting proinsulin conversion at baseline were newly detected phenotypes that independently predicted long-term glycaemic control. CONCLUSIONS/INTERPRETATION: Increased hepatic lipid content and impaired proinsulin conversion are new predictors, independent of change in body weight, for non-response to lifestyle intervention in addition to the confirmed factors, impaired insulin secretion and insulin sensitivity.

Effect of Crocus sativus Extract Supplementation in the Metabolic Control of People with Diabetes Mellitus Type 1: A Double-Blind Randomized Placebo-Controlled Trial.

Introduction-Background: Data from experimental trials show that Crocus sativus L. (saffron) is considered to improve glycemia, lipid profile, and blood pressure and reduce oxidative stress. So far, clinical trials have been conducted in individuals with metabolic syndrome and Diabetes Mellitus type 2 (DMT-2). The purpose of this study is to assess the effectiveness of saffron in individuals with Diabetes Mellitus type 1 (DMT-1). PATIENTS-METHODS: 61 individuals with DMT-1, mean age 48 years old (48.3 ± 14.6), 26 females (42.6%) were randomized to receive a new oral supplement in sachets containing probiotics, prebiotics, magnesium, and Crocus sativus L. extract or placebo containing probiotics, prebiotics and magnesium daily for 6 months. Glycemic control was assessed with a continuous glucose monitoring system and laboratory measurement of HbA1c and lipid profile was also examined. Blood pressure at baseline and end of intervention was also measured. Individuals were either on a continuous subcutaneous insulin infusion with an insulin pump or in multiple daily injection regimens. Diabetes distress and satiety were assessed through a questionnaire and body composition was assessed with bioelectrical impedance. RESULTS: At the end of the intervention, the two groups differed significantly only in serum triglycerides (p = 0.049). After 6 months of treatment, a significant reduction in the active group was observed in glycated hemoglobin (p = 0.046) and serum triglycerides (p = 0.021) compared to baseline. The other primary endpoints (glycemic control, lipid profile, blood pressure) did not differ within the groups from baseline to end of intervention, and there was no significant difference between the two groups. Diabetes distress score improved significantly only in the active group (p = 0.044), suggesting an overall improvement in diabetes disease burden in these individuals but that was not significant enough between the two groups. CONCLUSIONS: A probiotic supplement with saffron extract improves serum triglycerides in well-controlled people with DMT-1 and may potentially be a valuable adjunct for enhancing glycemic control.

Impact of breastfeeding duration on coagulation in women with and without history of gestational diabetes mellitus.

OBJECTIVE: Breastfeeding is associated with a reduced maternal risk for cardiovascular diseases. Since the underlying mechanisms are still poorly understood, we here examined the impact of breastfeeding on the plasmatic coagulation system in women with and without history of gestational diabetes mellitus (GDM). METHODS: 76 participants of the German Gestational Diabetes Study (PREG; NCT04270578) were examined 14 [interquartile range: 12-26] months after delivery with a 5-point oral glucose tolerance test. Global coagulation tests, prothrombotic coagulation proteins (FII/FVII/FVIII/FIX), antithrombotic proteins (antithrombin, protein C/S) and endothelial markers (von-Willebrand-factor and PAI-1) were determined. The Framingham Risk Score was used to estimate the 10-year cardiovascular risk. The impact of breastfeeding duration on coagulation was analyzed using multivariable linear models. RESULTS: The mean duration of breastfeeding was 11 [7-14] months. Overall, longer duration of breastfeeding was associated with lower cardiovascular risk (Framingham Risk Score, p=0.05) and was negatively associated with FIX (p=0.018). We detected an interaction between previous GDM and breastfeeding duration for FIX (pInteraction=0.017): only in women with GDM history was the duration of breastfeeding negatively associated with FIX activity (p=0.016). This association persisted in statistical models adjusted for age, body-mass index, insulin sensitivity, and C-reactive protein. The duration of breastfeeding was not associated with anticoagulant proteins and endothelial markers. CONCLUSION: Longer duration of breastfeeding is associated with lower cardiovascular risk and an improved coagulation profile. Women with GDM history appear to benefit particularly from prolonged breastfeeding.

[Prediabetes as a therapeutic challenge in internal medicine]. / Prädiabetes als therapeutische Herausforderung in der Inneren Medizin.

The term prediabetes describes a fasting blood glucose level that is elevated but not yet in the diabetic range, a blood glucose level that is elevated after 120 min in a standard 75­g oral glucose tolerance test, or both. The American Diabetes Association definition also includes glycated hemoglobin A (HbA1c). The incidence of prediabetes is rapidly increasing. Progression from normal glucose tolerance to diabetes is a continuous process. Insulin resistance and insulin secretory dysfunction, the simultaneous presence of which characterizes manifest diabetes, are already present in the prediabetic stage. Prediabetes is associated with an increased risk of diabetes; however, by no means all people with prediabetes go on to develop diabetes. Nevertheless, the identification of an increased risk of diabetes is still relevant insofar as it requires the adoption of diabetes prevention measures. Structured lifestyle intervention has been shown to be the most effective strategy for treating prediabetes. To increase its efficiency, it should, as far as possible, be made exclusively available to those people on whom it is most likely to confer a benefit. This would make it necessary to stratify people with prediabetes according to their risk profile. In a population of people at increased risk of diabetes (Tübingen Diabetes Family Study), a cluster analysis was performed, resulting in six clusters/subgroups. Within these, three high-risk subgroups were identified: Two of these risk groups show predominant insulin secretory dysfunction or predominant insulin resistance and high diabetes and cardiovascular risk. The third group shows a high risk of nephropathy and high mortality, but a comparatively lower diabetes risk. In general, prediabetes cannot yet be treated in a targeted pathophysiologically oriented manner. The new classification of prediabetes-based on pathophysiology-is now opening up new avenues for diabetes prevention. Current and future studies should confirm the assumption that the effectiveness of established, or not yet established, preventive measures depends on the respective subgroup.

Clinical Pathobiochemistry of Vitamin B12 Deficiency: Improving Our Understanding by Exploring Novel Mechanisms with a Focus on Diabetic Neuropathy.

Vitamin B12 (B12) is an essential cofactor of two important biochemical pathways, the degradation of methylmalonic acid and the synthesis of methionine from homocysteine. Methionine is an important donor of methyl groups for numerous biochemical reactions, including DNA synthesis and gene regulation. Besides hematological abnormalities (megaloblastic anemia or even pancytopenia), a deficiency in B12 may cause neurological symptoms, including symptoms resembling diabetic neuropathy. Although extensively studied, the underlining molecular mechanism for the development of diabetic peripheral neuropathy (DPN) is still unclear. Most studies have found a contribution of oxidative stress in the development of DPN. Detailed immunohistochemical investigations in sural nerve biopsies obtained from diabetic patients with DPN point to an activation of inflammatory pathways induced via elevated advanced glycation end products (AGE), ultimately resulting in increased oxidative stress. Similar results have been found in patients with B12 deficiency, indicating that the observed neural changes in patients with DPN might be caused by cellular B12 deficiency. Since novel results show that B12 exerts intrinsic antioxidative activity in vitro and in vivo, B12 may act as an intracellular, particularly as an intramitochondrial, antioxidant, independent from its classical, well-known cofactor function. These novel findings may provide a rationale for the use of B12 for the treatment of DPN, even in subclinical early states.

Lower Hepatic Fat Is Associated With Improved Insulin Secretion in a High-Risk Prediabetes Subphenotype During Lifestyle Intervention.

The objective of this work was to investigate whether impaired insulin secretion can be restored by lifestyle intervention in specific subphenotypes of prediabetes. We assigned 1,045 participants from the Prediabetes Lifestyle Intervention Study (PLIS) to six recently established prediabetes clusters. Insulin secretion was assessed by a C-peptide-based index derived from oral glucose tolerance tests and modeled from three time points during a 1-year intervention. We also analyzed the change of glycemia, insulin sensitivity, and liver fat. All prediabetes high-risk clusters (cluster 3, 5, and 6) had improved glycemic traits during the lifestyle intervention, whereas insulin secretion only increased in clusters 3 and 5 (P < 0.001); however, high liver fat in cluster 5 was associated with a failure to improve insulin secretion (Pinteraction < 0.001). Thus, interventions to reduce liver fat have the potential to improve insulin secretion in a defined subgroup of prediabetes.

Causes and metabolic consequences of Fatty liver.

Type 2 diabetes and cardiovascular disease represent a serious threat to the health of the population worldwide. Although overall adiposity and particularly visceral adiposity are established risk factors for these diseases, in the recent years fatty liver emerged as an additional and independent factor. However, the pathophysiology of fat accumulation in the liver and the cross-talk of fatty liver with other tissues involved in metabolism in humans are not fully understood. Here we discuss the mechanisms involved in the pathogenesis of hepatic fat accumulation, particularly the roles of body fat distribution, nutrition, exercise, genetics, and gene-environment interaction. Furthermore, the effects of fatty liver on glucose and lipid metabolism, specifically via induction of subclinical inflammation and secretion of humoral factors, are highlighted. Finally, new aspects regarding the dissociation of fatty liver and insulin resistance are addressed.

Impaired Metabolic Health and Low Cardiorespiratory Fitness Independently Associate With Subclinical Atherosclerosis in Obesity.

CONTEXT: For a given body mass index (BMI), both impaired metabolic health (MH) and reduced cardiorespiratory fitness (CRF) associate with increased risk of cardiovascular disease (CVD). OBJECTIVE: It remains unknown whether both risk phenotypes relate to CVD independently of each other, and whether these relationships differ in normal weight, overweight, and obese subjects. METHODS: Data from 421 participants from the Tübingen Diabetes Family Study, who had measurements of anthropometrics, metabolic parameters, CRF (maximal aerobic capacity [VO2max]) and carotid intima-media thickness (cIMT), an early marker of atherosclerosis, were analyzed. Subjects were divided by BMI and MH status into 6 phenotypes. RESULTS: In univariate analyses, older age, increased BMI, and a metabolic risk profile correlated positively, while insulin sensitivity and VO2max negatively with cIMT. In multivariable analyses in obese subjects, older age, male sex, lower VO2max (std. ß -0.21, P = 0.002) and impaired MH (std. ß 0.13, P = 0.02) were independent determinants of increased cIMT. After adjustment for age and sex, subjects with metabolically healthy obesity (MHO) had higher cIMT than subjects with metabolically healthy normal weight (MHNW; 0.59 ±â€…0.009 vs 0.52 ±â€…0.01 mm; P < 0.05). When VO2max was additionally included in this model, the difference in cIMT between MHO and MHNW groups became statistically nonsignificant (0.58 ±â€…0.009 vs 0.56 ±â€…0.02 mm; P > 0.05). CONCLUSION: These data suggest that impaired MH and low CRF independently determine increased cIMT in obese subjects and that low CRF may explain part of the increased CVD risk observed in MHO compared with MHNW.

Diabetes and the Prostate: Elevated Fasting Glucose, Insulin Resistance and Higher Levels of Adrenal Steroids in Prostate Cancer.

Although epidemiological studies suggest a lower prostate cancer incidence rate in patients with type 2 diabetes, cancer survival is markedly reduced. Underlying mechanisms that connect the two diseases are still unclear. Potential links between type 2 diabetes and prostate cancer are hallmarks of the metabolic syndrome, such as hyperglycemia and dyslipidemia. Therefore, we explored the systemic metabolism of 103 prostate cancer patients with newly diagnosed and yet untreated prostate cancer compared to 107 healthy controls, who were carefully matched for age and BMI. Here, we report that patients with prostate cancer display higher fasting blood glucose levels and insulin resistance, without changes in insulin secretion. With respect to lipid metabolism, serum triglyceride levels were lower in patients with prostate cancer. In addition, we report increased adrenal steroid biosynthesis in these patients. Our results indicate that higher fasting glucose levels in patients with prostate cancer may be explained at least in part by insulin resistance, due to the enhanced synthesis of adrenal steroids.

Empagliflozin Improves Insulin Sensitivity of the Hypothalamus in Humans With Prediabetes: A Randomized, Double-Blind, Placebo-Controlled, Phase 2 Trial.

OBJECTIVE: Insulin action in the human brain reduces food intake, improves whole-body insulin sensitivity, and modulates body fat mass and its distribution. Obesity and type 2 diabetes are often associated with brain insulin resistance, resulting in impaired brain-derived modulation of peripheral metabolism. So far, no pharmacological treatment for brain insulin resistance has been established. Since sodium-glucose cotransporter 2 (SGLT2) inhibitors lower glucose levels and modulate energy metabolism, we hypothesized that SGLT2 inhibition may be a pharmacological approach to reverse brain insulin resistance. RESEARCH DESIGN AND METHODS: In this randomized, double-blind, placebo-controlled clinical trial, 40 patients (mean ± SD; age 60 ± 9 years; BMI 31.5 ± 3.8 kg/m2) with prediabetes were randomized to receive 25 mg empagliflozin every day or placebo. Before and after 8 weeks of treatment, brain insulin sensitivity was assessed by functional MRI combined with intranasal administration of insulin to the brain. RESULTS: We identified a significant interaction between time and treatment in the hypothalamic response to insulin. Post hoc analyses revealed that only empagliflozin-treated patients experienced increased hypothalamic insulin responsiveness. Hypothalamic insulin action significantly mediated the empagliflozin-induced decrease in fasting glucose and liver fat. CONCLUSIONS: Our results corroborate insulin resistance of the hypothalamus in humans with prediabetes. Treatment with empagliflozin for 8 weeks was able to restore hypothalamic insulin sensitivity, a favorable response that could contribute to the beneficial effects of SGLT2 inhibitors. Our findings position SGLT2 inhibition as the first pharmacological approach to reverse brain insulin resistance, with potential benefits for adiposity and whole-body metabolism.

The German Gestational Diabetes Study (PREG), a prospective multicentre cohort study: rationale, methodology and design.

INTRODUCTION: Even well-treated gestational diabetes mellitus (GDM) might still have impact on long-term health of the mother and her offspring, although this relationship has not yet been conclusively studied. Using in-depth phenotyping of the mother and her offspring, we aim to elucidate the relationship of maternal hyperglycaemia during pregnancy and adequate treatment, and its impact on the long-term health of both mother and child. METHODS: The multicentre PREG study, a prospective cohort study, is designed to metabolically and phenotypically characterise women with a 75-g five-point oral glucose tolerance test (OGTT) during, and repeatedly after pregnancy. Outcome measures are maternal glycaemia during OGTTs, birth outcome and the health and growth development of the offspring. The children of the study participants are followed up until adulthood with developmental tests and metabolic and epigenetic phenotyping in the PREG Offspring study. A total of 800 women (600 with GDM, 200 controls) will be recruited. ETHICS AND DISSEMINATION: The study protocol has been approved by all local ethics committees. Results will be disseminated via conference presentations and peer-reviewed publications. TRIAL REGISTRATION NUMBER: The PREG study and the PREG Offspring study are registered with Clinical Trials (ClinicalTrials.gov identifiers: NCT04270578, NCT04722900).

Detection and Characterization of Phosphorylation, Glycosylation, and Fatty Acid Bound to Fetuin A in Human Blood.

The hepatokine fetuin A (Fet A) has been associated with diverse pathological states such as insulin resistance, type 2 diabetes, macrovascular disease, and systemic ectopic and vascular calcification. Fet A may also play a role in tumor growth and metastasis. The biological activity of Fet A may be affected by various modifications, including phosphorylation, O- and N-glycosylation and fatty acid binding. We developed an antibody-based assay for the detection of Fet A phosphorylated at serine 312. Fatty acid pattern was determined by gas chromatography. Using the antibody, we found that the phosphorylation was stable in human plasma or serum at room temperature for 8 h. We observed that Fet A is present in several glycosylation forms in human plasma, but the extent of Ser312 phosphorylation was not associated with glycosylation. The phosphorylation pattern did not change during an oral glucose tolerance test (0-120 min). We further found that human Fet A binds preferentially saturated fatty acids (>90%) at the expense of mono- and poly-unsaturated fatty acids. Our results indicate that different molecular species of Fet A are present in human plasma and that these different modifications may determine the different biological effects of Fet A.

Comparison of Premixed Human Insulin 30/70 to Biphasic Aspart 30 in Well-Controlled Patients with Type 2 Diabetes Using Continuous Glucose Monitoring.

AIM: To compare in terms of glycemic variability two premixed insulins, Premixed Human Insulin 30/70 (PHI) and Biphasic Aspart 30 (BiAsp30), using Continuous Glucose Monitoring (CGM) and to estimate the correlation of Glycated Albumin (GA) and Fructosamine (FA) with CGM data. Patients-Data: A total of 36 well-controlled patients with type 2 Diabetes Mellitus (T2DM) underwent 7-day CGM with PHI and subsequently with BiAsp30. GA and FA were measured at the first and last day of each week of CGM. RESULTS: BiAsp30 was associated with lower Average Blood Glucose (ABG) during the 23:00-03:00 period (PHI: 135.08 ± 28.94 mg/dL, BiAsp30: 117.75 ± 21.24 mg/dL, p < 0.001) and the 00:00-06:00 period (PHI: 120.42 ± 23.13 mg/dL, BiAsp30: 111.17 ± 14.74 mg/dL, p = 0.008), as well as with more time below range (<70 mg/dL) (TBR) during the 23:00-03:00 period in the week (PHI: 3.65 ± 5.93%, BiAsp30: 11.12 ± 16.07%, p = 0.005). PHI was associated with lower ABG before breakfast (PHI: 111.75 ± 23.9 mg/dL, BiAsp30: 128.25 ± 35.9 mg/dL, p = 0.013). There were no differences between the two groups in ABG, Time In Range and Time Below Range during the entire 24-h period for 7 days, p = 0.502, p = 0.534, and p = 0.258 respectively, and in TBR for the 00:00-06:00 period p = 0.253. Total daily insulin requirements were higher for BiAsp30 (PHI: 47.92 ± 12.18 IU, BiAsp30: 49.58 ± 14.12 IU, p = 0.001). GA and FA correlated significantly with ABG (GA: r = 0.512, p = 0.011, FA: r = 0.555, p = 0.005). CONCLUSIONS: In well-controlled patients with T2DM, BiAsp30 is an equally effective alternative to PHI.

Slow deep breathing modulates cardiac vagal activity but does not affect peripheral glucose metabolism in healthy men.

Parasympathetic nervous system innervates peripheral organs including pancreas, hepatic portal system, and gastrointestinal tract. It thereby contributes to the regulation of whole-body glucose metabolism especially in the postprandial state when it promotes secretion of insulin and enhances its action in major target organs. We now aimed to evaluate the effect of parasympathetic modulation on human glucose metabolism. We used slow deep breathing maneuvers to activate the parasympathetic nervous system and tested for effects on metabolism during an oral glucose tolerance test in a randomized, controlled, cross-over trial in 15 healthy young men. We used projections towards the heart as a readout for parasympathetic activity. When analyzing heart rate variability, there was a significant increase of RMSSD (root mean square of successive differences) when participants performed slow deep breathing compared to the control condition, indicating a modulation of parasympathetic activity. However, no statistically significant effects on peripheral glucose metabolism or energy expenditure after the glucose tolerance test were detected. Of note, we detected a significant association between mean heart rate and serum insulin and C-peptide concentrations. While we did not find major effects of slow deep breathing on glucose metabolism, our correlational results suggest a link between the autonomic nervous system and insulin secretion after oral glucose intake. Future studies need to unravel involved mechanisms and develop potential novel treatment approaches for impaired insulin secretion in diabetes.

Free fatty acids, glicentin and glucose-dependent insulinotropic polypeptide as potential major determinants of fasting substrate oxidation.

The selection of carbohydrates or fat to generate intracellular energy is thought to be crucial for long-term metabolic health. While most studies assess fuel selection after a metabolic challenge, the determinants of substrate oxidation in the fasted state remain largely unexplored. We therefore assessed the respiratory quotient by indirect calorimetry as a read-out for substrate oxidation following an overnight fast. This cross-sectional analysis consisted of 192 (92 women, 100 men) either lean or obese participants. Following an overnight fast, the respiratory quotient (RQ) was assessed, after which a 5-point 75-g oral glucose tolerance test was performed. Unlike glucose and insulin, fasting free fatty acids (FFA) correlated negatively with fasting RQ (p < 0.0001). Participants with high levels of the ketone body ß-hydroxybutyric acid had significantly lower RQ values. Fasting levels of glucose-dependent insulinotropic polypeptide (GIP) and glicentin were positively associated with fasting RQ (all p ≤ 0.03), whereas GLP-1 showed no significant association. Neither BMI, nor total body fat, nor body fat distribution correlated with fasting RQ. No relationship between the RQ and diabetes or the metabolic syndrome could be observed. In the fasting state, FFA concentrations were strongly linked to the preferentially oxidized substrate. Our data did not indicate any relationship between fasting substrate oxidation and metabolic diseases, including obesity, diabetes, and the metabolic syndrome. Since glicentin and GIP are linked to fuel selection in the fasting state, novel therapeutic approaches that target these hormones may have the potential to modulate substrate oxidation.

Follow-up whole-body assessment of adipose tissue compartments during a lifestyle intervention in a large cohort at increased risk for type 2 diabetes.

PURPOSE: To assess adipose body compartments with magnetic resonance (MR) imaging and MR spectroscopy during a lifestyle intervention program that included optimized nutrition and controlled physical activity in subjects at increased risk for type 2 diabetes to determine factors that may help predict an increase in insulin sensitivity following the intervention. MATERIALS AND METHODS: This prospective study was approved by the local review board. All participants gave written informed consent. MR imaging and MR spectroscopy were performed in 243 subjects (99 men and 144 women) before and 9 months after enrollment in a lifestyle intervention program. The results of whole-body MR imaging were used to calculate tissue profiles, differentiating between adipose tissue--especially visceral adipose tissue--and lean tissue. The concentration of hepatic lipids and intramyocellular lipids in the anterior tibial and soleus muscles was determined with MR spectroscopy, and insulin sensitivity was estimated by using an oral glucose tolerance test. The Student t test was used to assess differences between groups, and multivariate regression models were used to assess the value of adipose tissue compartments in the prediction of insulin sensitivity. RESULTS: Compared with women, men had almost twice the amount of visceral adipose tissue and a smaller amount of total adipose tissue (25.9% for men and 36.9% for women) at baseline. In addition, their insulin sensitivity was significantly lower than that of women. The most pronounced changes in adipose tissue were detected for visceral adipose tissue (from 4.9 L to 4.1 L [ie, -15.1%] in men and from 2.3 L to 1.9 L [ie, -15.8%] in women) and hepatic lipids (from 8.6% to 5.4% [ie, -36.8%] in men and from 5.1% to 4.3% [ie, -16.5%] in women). The mean insulin sensitivity improved significantly (from 11.3 arbitrary units [au] to 14.6 au [ie, +29.9%] in men and from 13.6 au to 14.6 au [ie, +7.5%] in women), with 70 of the 99 men (71%) and 84 of 144 women (58%) showing an increase in insulin sensitivity. In men, low concentrations of visceral adipose tissue, hepatic lipids, and abdominal subcutaneous fat at baseline were predictive of successful intervention in terms of changes in insulin sensitivity; in women, only low hepatic lipid levels were significantly predictive of successful intervention. CONCLUSION: Visceral adipose tissue and hepatic lipids, as assessed with MR imaging and MR spectroscopy, can be significantly reduced during lifestyle intervention. Their baseline values emerged as predictive factors for an improvement of insulin sensitivity.

Environmental and genetic determinants of fatty liver in humans.

Non-alcoholic fatty liver represents one of the most prevalent conditions affecting about one third of the general population in the Western world, and its prevalence is continuously increasing parallel to the epidemics of obesity. Non-alcoholic fatty liver is a strong predictor of non-alcoholic steatohepatitis, but also of cirrhosis, end-stage liver disease and hepatocellular carcinoma. In recent years, non-alcoholic fatty liver (in addition to overall and visceral obesity) has emerged as a risk factor for insulin resistance, hypertension, dyslipidemia, cardiovascular events and type 2 diabetes. This review summarizes the information currently available about the mechanisms involved in liver fat accumulation (e.g. hepatic lipid supply, de novo lipogenesis, lipid oxidation and the packaging and secretion of triglycerides in the form of very-low-density lipoproteins). New aspects concerning mechanisms potentially leading to a 'dissociation' of fatty liver and insulin resistance are also discussed. Understanding the pathogenesis of fatty liver and its complications, including the identification of new factors secreted from the liver under excess fat accumulation that are involved in the regulation of metabolism ('hepatokines'), is crucial in order to develop and implement efficient prevention and treatment strategies.

Diabetes and Heart Failure: Is it Hyperglycemia or Hyperinsulinemia?

The cardiac effects of exogenously administered insulin for the treatment of diabetes (DM) have recently attracted much attention. In particular, it has been questioned whether insulin is the appropriate treatment for patients with type 2 diabetes mellitus and heart failure. While several old and some new studies suggested that insulin treatment has beneficial effects on the heart, recent observational studies indicate associations of insulin treatment with an increased risk of developing or worsening of pre-existing heart failure and higher mortality rates. However, there is actually little evidence that the associations of insulin administration with any adverse outcomes are causal. On the other hand, insulin clearly causes weight gain and may also cause serious episodes of hypoglycemia. Moreover, excess of insulin (hyperinsulinemia), as often seen with the use of injected insulin, seems to predispose to inflammation, hypertension, dyslipidemia, atherosclerosis, heart failure, and arrhythmias. Nevertheless, it should be stressed that most of the data concerning the effects of insulin on cardiac function derive from in vitro studies with isolated animal hearts. Therefore, the relevance of the findings of such studies for humans should be considered with caution. In the present review, we summarize the existing data about the potential positive and negative effects of insulin on the heart and attempt to answer the question whether any adverse effects of insulin or the consequences of hyperglycemia are more important and may provide a better explanation of the close association of DM with heart failure.