Kombinierter AHG- und PTA-Mangel

Es wird über die Kombination eines Faktor-VIII- und Faktor-XI-Mangels bei einem Patienten mit schwerer Blutungsneigung berichtet. Die Schwierigkeiten der Differentialdiagnose werden aufgezeigt und ähnliche Fälle in der Literatur diskutiert.

Acute dietary fat intake initiates alterations in energy metabolism and insulin resistance

BACKGROUND

Dietary intake of saturated fat is a likely contributor to nonalcoholic fatty liver disease (NAFLD) and insulin resistance, but the mechanisms that initiate these abnormalities in humans remain unclear. We examined the effects of a single oral saturated fat load on insulin sensitivity, hepatic glucose metabolism, and lipid metabolism in humans. Similarly, initiating mechanisms were examined after an equivalent challenge in mice.

METHODS

Fourteen lean, healthy individuals randomly received either palm oil (PO) or vehicle (VCL). Hepatic metabolism was analyzed using in vivo 13C/31P/1H and ex vivo 2H magnetic resonance spectroscopy before and during hyperinsulinemic-euglycemic clamps with isotope dilution. Mice underwent identical clamp procedures and hepatic transcriptome analyses.

RESULTS

PO administration decreased whole-body, hepatic, and adipose tissue insulin sensitivity by 25%, 15%, and 34%, respectively. Hepatic triglyceride and ATP content rose by 35% and 16%, respectively. Hepatic gluconeogenesis increased by 70%, and net glycogenolysis declined by 20%. Mouse transcriptomics revealed that PO differentially regulates predicted upstream regulators and pathways, including LPS, members of the TLR and PPAR families, NF-κB, and TNF-related weak inducer of apoptosis (TWEAK).

CONCLUSION

Saturated fat ingestion rapidly increases hepatic lipid storage, energy metabolism, and insulin resistance. This is accompanied by regulation of hepatic gene expression and signaling that may contribute to development of NAFLD.REGISTRATION. ClinicalTrials.gov NCT01736202.

FUNDING

Germany: Ministry of Innovation, Science, and Research North Rhine-Westfalia, German Federal Ministry of Health, Federal Ministry of Education and Research, German Center for Diabetes Research, German Research Foundation, and German Diabetes Association. Portugal: Portuguese Foundation for Science and Technology, FEDER - European Regional Development Fund, Portuguese Foundation for Science and Technology, and Rede Nacional de Ressonância Magnética Nuclear.

Inflammatory markers are associated with cardiac autonomic dysfunction in recent-onset type 2 diabetes

OBJECTIVE

Cardiovascular autonomic neuropathy is a common but underestimated diabetes-related disorder. Associations between cardiovascular autonomic dysfunction and subclinical inflammation, both risk factors of diabetic comorbidities and mortality, have been proposed in non-diabetic populations, while data for type 1 and type 2 diabetes are conflicting. Our aim was to investigate associations between inflammation-related biomarkers and cardiac autonomic dysfunction in patients with diabetes.

METHODS

We characterised the associations between seven biomarkers of subclinical inflammation and cardiac autonomic dysfunction based on heart rate variability and cardiovascular autonomic reflex tests (CARTs) in 161 individuals with type 1 and 352 individuals with type 2 diabetes (time since diagnosis of diabetes <1 year). Analyses were adjusted for age, sex, anthropometric, metabolic and lifestyle factors, medication and cardiovascular comorbidities.

RESULTS

In individuals with type 2 diabetes, higher serum interleukin (IL)-18 was associated with lower vagal activity (p≤0.015 for association with CARTs), whereas higher levels of total and high-molecular-weight adiponectin showed associations with very low frequency power, an indicator of reduced sympathetic activity (p≤0.014). Higher levels of soluble intercellular adhesion molecule-1 were associated with indicators of both lower vagal (p=0.025) and sympathetic (p=0.008) tone, soluble E-selectin with one indicator of lower vagal activity (p=0.047). Serum C-reactive protein and IL-6 were also related to cardiac autonomic dysfunction, but these associations were explained by confounding factors. No consistent associations were found in individuals with type 1 diabetes.

CONCLUSIONS

Biomarkers of inflammation were differentially associated with diminished cardiac autonomic dysfunction in recent-onset type 2 diabetes.

Variants in Genes Controlling Oxidative Metabolism Contribute to Lower Hepatic ATP Independent of Liver Fat Content in Type 1 Diabetes

Type 1 diabetes has been recently linked to nonalcoholic fatty liver disease (NAFLD), which is known to associate with insulin resistance, obesity, and type 2 diabetes. However, the role of insulin resistance and hyperglycemia for hepatic energy metabolism is yet unclear. To analyze early abnormalities in hepatic energy metabolism, we examined 55 patients with recently diagnosed type 1 diabetes. They underwent hyperinsulinemic-normoglycemic clamps with [6,6-(2)H2]glucose to assess whole-body and hepatic insulin sensitivity. Hepatic γATP, inorganic phosphate (Pi), and triglyceride concentrations (hepatocellular lipid content [HCL]) were measured with multinuclei magnetic resonance spectroscopy ((31)P/(1)H-MRS). Glucose-tolerant humans served as control (CON) (n = 57). Whole-body insulin sensitivity was 44% lower in patients than in age- and BMI-matched CON. Hepatic γATP was 15% reduced (2.3 ± 0.6 vs. 2.7 ± 0.6 mmol/L, P < 0.001), whereas hepatic Pi and HCL were similar in patients when compared with CON. Across all participants, hepatic γATP correlated negatively with glycemia and oxidized LDL. Carriers of the PPARG G allele (rs1801282) and noncarriers of PPARGC1A A allele (rs8192678) had 21 and 13% lower hepatic ATP concentrations. Variations in genes controlling oxidative metabolism contribute to a reduction in hepatic ATP in the absence of NAFLD, suggesting that alterations in hepatic mitochondrial function may precede diabetes-related liver diseases.

Sfrp5 associates with beta-cell function in humans

BACKGROUND

Secreted frizzled-related protein (Sfrp)5 improves insulin sensitivity, but impairs beta-cell function in rodents. However, the relationship between Sfrp5, insulin sensitivity and secretion in humans is currently unclear. Therefore, the aim of the study was to characterize the associations between serum Sfrp5 and indices of insulin sensitivity and beta-cell function from dynamic measurements using oral glucose tolerance tests (OGTT) in humans.

MATERIAL AND METHODS

This study enrolled 194 individuals with nonalcoholic fatty liver disease (NAFLD), who were diagnosed based on ultrasound and liver transaminases and underwent a frequent sampling 75-g OGTT. Fasting serum Sfrp5 was measured by ELISA. Associations were assessed with several indices of insulin sensitivity and beta-cell function derived from glucose, insulin and C-peptide concentrations during the OGTT.

RESULTS

Circulating Sfrp5 associated inversely with the insulinogenic index based on C-peptide (rs = -0·244, P = 0·001), but not with the insulinogenic index based on insulin levels (rs = -0·007, P = 0·926) after adjustment for age, sex and body mass index. Sfrp5 inversely correlated only with QUICKI as a marker of insulin sensitivity in the model adjusted for age and sex (rs = -0·149, P = 0·039). These associations were not influenced by the additional adjustment for hepatic steatosis index.

CONCLUSIONS

The inverse association of serum Sfrp5 with beta-cell function suggests a detrimental role of Sfrp5 for insulin secretion also in humans. The severity of NAFLD does not appear to affect this relationship. The weak association between serum Sfrp5 and insulin sensitivity was partially explained by body mass.

Adiponectin, markers of subclinical inflammation and nerve conduction in individuals with recently diagnosed type 1 and type 2 diabetes

OBJECTIVE

Subclinical inflammation has been implicated in the development of diabetic sensorimotor polyneuropathy (DSPN), but studies using electrophysiological assessment as outcomes are scarce. Therefore, we aimed to investigate associations of biomarkers reflecting different aspects of subclinical inflammation with motor and sensory nerve conduction velocity (NCV) in individuals with diabetes.

DESIGN AND METHODS

Motor and sensory NCV was assessed in individuals with recently diagnosed type 2 (n=352) or type 1 diabetes (n=161) from the baseline cohort of the observational German Diabetes Study. NCV sum scores were calculated for median, ulnar and peroneal motor as well as median, ulnar and sural sensory nerves. Associations between inflammation-related biomarkers, DSPN and NCV sum scores were estimated using multiple regression models.

RESULTS

In type 2 diabetes, high serum interleukin (IL)-6 was associated with the presence of DSPN and reduced motor NCV. Moreover, higher levels of high-molecular weight (HMW) adiponectin, total adiponectin and their ratio were associated with prevalent DSPN and both diminished motor and sensory NCV, whereas no consistent associations were observed for C-reactive protein, IL18, soluble intercellular adhesion molecule-1 and E-selectin. In type 1 diabetes, only HMW and total adiponectin showed positive associations with motor NCV.

CONCLUSIONS

Our results point to a link between IL6 and both DSPN and slowed motor NCV in recently diagnosed type 2 diabetes. The reverse associations between adiponectin and NCV in type 1 and type 2 diabetes are intriguing, and further studies should explore whether they may reflect differences in the pathogenesis of DSPN in both diabetes types.

Intake of Lactobacillus reuteri improves incretin and insulin secretion in glucose-tolerant humans: a proof of concept

OBJECTIVE

Ingestion of probiotics can modify gut microbiota and alter insulin resistance and diabetes development in rodents. We hypothesized that daily intake of Lactobacillus reuteri increases insulin sensitivity by changing cytokine release and insulin secretion via modulation of the release of glucagon-like peptides (GLP)-1 and -2.

RESEARCH DESIGN AND METHODS

A prospective, double-blind, randomized trial was performed in 21 glucose-tolerant humans (11 lean: age 49 ± 7 years, BMI 23.6 ± 1.7 kg/m(2); 10 obese: age 51 ± 7 years, BMI 35.5 ± 4.9 kg/m(2)). Participants ingested 10(10) b.i.d. L. reuteri SD5865 or placebo over 4 weeks. Oral glucose tolerance and isoglycemic glucose infusion tests were used to assess incretin effect and GLP-1 and GLP-2 secretion, and euglycemic-hyperinsulinemic clamps with [6,6-(2)H2]glucose were used to measure peripheral insulin sensitivity and endogenous glucose production. Muscle and hepatic lipid contents were assessed by (1)H-magnetic resonance spectroscopy, and immune status, cytokines, and endotoxin were measured with specific assays.

RESULTS

In glucose-tolerant volunteers, daily administration of L. reuteri SD5865 increased glucose-stimulated GLP-1 and GLP-2 release by 76% (P < 0.01) and 43% (P < 0.01), respectively, compared with placebo, along with 49% higher insulin (P < 0.05) and 55% higher C-peptide secretion (P < 0.05). However, the intervention did not alter peripheral and hepatic insulin sensitivity, body mass, ectopic fat content, or circulating cytokines.

CONCLUSIONS

Enrichment of gut microbiota with L. reuteri increases insulin secretion, possibly due to augmented incretin release, but does not directly affect insulin sensitivity or body fat distribution. This suggests that oral ingestion of one specific strain may serve as a novel therapeutic approach to improve glucose-dependent insulin release.

Pancreatic adipose tissue infiltration, parenchymal steatosis and beta cell function in humans

AIMS/HYPOTHESIS

This study aimed to perform a comprehensive analysis of interlobular, intralobular and parenchymal pancreatic fat in order to assess their respective effects on beta cell function.

METHODS

Fifty-six participants (normal glucose tolerance [NGT] (n = 28), impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) (n = 14) and patients with type 2 diabetes (n = 14)) underwent a frequent-sampling OGTT and non-invasive magnetic resonance imaging (MRI; whole-body and pancreatic) and proton magnetic resonance spectroscopy ((1)H-MRS; liver and pancreatic fat). Total pancreatic fat was assessed by a standard 2 cm(3) (1)H-MRS method, intralobular fat by 1 cm(3) (1)H-MRS that avoided interlobular fat within modified DIXON (mDIXON) water images, and parenchymal fat by a validated mDIXON-MRI fat-fraction method.

RESULTS

Comparison of (1)H-MRS techniques revealed an inhomogeneous distribution of interlobular and intralobular adipose tissue, which increased with decreasing glucose tolerance. mDIXON-MRI measurements provided evidence against uniform steatosis, revealing regions of parenchymal tissue void of lipid accumulation in all participants. Total (r = 0.385, p < 0.01) and intralobular pancreas adipose tissue infiltration (r = 0.310, p < 0.05) positively associated with age, but not with fasting or 2 h glucose levels, BMI or visceral fat content (all p > 0.5). Furthermore, no associations were found between total and intralobular pancreatic adipose tissue infiltration and insulin secretion or beta cell function within NGT, IFG/IGT or patients with type 2 diabetes (all p > 0.2).

CONCLUSIONS/INTERPRETATION

The pancreas does not appear to be another target organ for abnormal endocrine function because of ectopic parenchymal fat storage. No relationship was found between pancreatic adipose tissue infiltration and beta cell function, regardless of glucose tolerance status.

Characterization of the peak at 2.06 ppm in (31) P magnetic resonance spectroscopy of human liver: phosphoenolpyruvate or phosphatidylcholine?

High field MR scanners can resolve a metabolite resonating at 2.06 ppm in the in vivo proton-decoupled liver (31) P MR spectrum. Traditionally this peak has been assigned to phosphoenolpyruvate (PEP), the key metabolite for gluconeogenesis. However, recent evidence supported the assignment to biliary phosphatidylcholine (PtdCh), which is produced in the liver and stored in the gall bladder. To elucidate the respective contributions of PtdCh and PEP to the in vivo resonance at 2.06 ppm (PEP-PtdCh), we made phantom measurements that confirmed that both biliary PtdCh and PEP resonate approximately at 2 ppm. The absolute quantification of PEP-PtdCh yielded concentrations ranging from 0.6 to 2.0 mmol/l, with mean coefficients of variation of 4.8% for intraday and 7.2% for interday reproducibility in healthy volunteers. The T1 relaxation time of PEP-PtdCh was 0.97 ± 0.30 s in the liver and 0.44 ± 0.11 s in the gallbladder. Ingestion of a mixed meal decreased the concentration of PtdCh-PEP by approximately 12%. In the retrospective analysis, PEP-PtdCh was 68% higher in the liver of subjects with gallbladder infiltration of the volume of interest (VOI) compared with those without gallbladder infiltration. PEP-PtdCh was also significantly higher in the liver of cholecystectomy patients compared with volunteers without gallbladder infiltration, which suggests increased intrahepatic bile fluid as a compensation for gall bladder removal. These results show that liver PtdCh is the major component of the resonance at 2.06 ppm and that careful VOI positioning is mandatory to avoid interference from the gallbladder.

Effects of intranasal insulin on hepatic fat accumulation and energy metabolism in humans

Studies in rodents suggest that insulin controls hepatic glucose metabolism through brain-liver crosstalk, but human studies using intranasal insulin to mimic central insulin delivery have provided conflicting results. In this randomized controlled crossover trial, we investigated the effects of intranasal insulin on hepatic insulin sensitivity (HIS) and energy metabolism in 10 patients with type 2 diabetes and 10 lean healthy participants (CON). Endogenous glucose production was monitored with [6,6-(2)H2]glucose, hepatocellular lipids (HCLs), ATP, and inorganic phosphate concentrations with (1)H/(31)P magnetic resonance spectroscopy. Intranasal insulin transiently increased serum insulin levels followed by a gradual lowering of blood glucose in CON only. Fasting HIS index was not affected by intranasal insulin in CON and patients. HCLs decreased by 35% in CON only, whereas absolute hepatic ATP concentration increased by 18% after 3 h. A subgroup of CON received intravenous insulin to mimic the changes in serum insulin and blood glucose levels observed after intranasal insulin. This resulted in a 34% increase in HCLs without altering hepatic ATP concentrations. In conclusion, intranasal insulin does not affect HIS but rapidly improves hepatic energy metabolism in healthy humans, which is independent of peripheral insulinemia. These effects are blunted in patients with type 2 diabetes.

Adaptation of hepatic mitochondrial function in humans with non-alcoholic fatty liver is lost in steatohepatitis

The association of hepatic mitochondrial function with insulin resistance and non-alcoholic fatty liver (NAFL) or steatohepatitis (NASH) remains unclear. This study applied high-resolution respirometry to directly quantify mitochondrial respiration in liver biopsies of obese insulin-resistant humans without (n = 18) or with (n = 16) histologically proven NAFL or with NASH (n = 7) compared to lean individuals (n = 12). Despite similar mitochondrial content, obese humans with or without NAFL had 4.3- to 5.0-fold higher maximal respiration rates in isolated mitochondria than lean persons. NASH patients featured higher mitochondrial mass, but 31%-40% lower maximal respiration, which associated with greater hepatic insulin resistance, mitochondrial uncoupling, and leaking activity. In NASH, augmented hepatic oxidative stress (H2O2, lipid peroxides) and oxidative DNA damage (8-OH-deoxyguanosine) was paralleled by reduced anti-oxidant defense capacity and increased inflammatory response. These data suggest adaptation of the liver ("hepatic mitochondrial flexibility") at early stages of obesity-related insulin resistance, which is subsequently lost in NASH.

Serum Chemerin Concentrations Associate with Beta-Cell Function, but Not with Insulin Resistance in Individuals with Non-Alcoholic Fatty Liver Disease (NAFLD)

The novel adipokine chemerin has been related to insulin-resistant states such as obesity and non alcoholic fatty liver disease (NAFLD). However, its association with insulin resistance and beta cell function remains controversial. The main objective was to examine whether serum chemerin levels associate with insulin sensitivity and beta cell function independently of body mass index (BMI), by studying consecutive outpatients of the hepatology clinics of a European university hospital. Individuals (n=196) with NAFLD were stratified into persons with normal glucose tolerance (NGT; n=110), impaired glucose tolerance (IGT; n=51) and type 2 diabetes (T2D; n=35) and the association between serum chemerin and measures of insulin sensitivity and beta cell function as assessed during fasting and during oral glucose tolerance test (OGTT) was measured. Our results showed that serum chemerin positively associated with BMI (P=0.0007) and C peptide during OGTT (P<0.004), but not with circulating glucose, insulin, lipids or liver enzymes (all P>0.18). No BMI independent relationships of chemerin with fasting and OGTT derived measures of insulin sensitivity were found (P>0.5). Chemerin associated positively with fasting beta cell function as well as the OGTT derived insulinogenic index IGI_cp and the adaptation index after adjustment for age, sex and BMI (P=0.002-0.007), and inversely with the insulin/C peptide ratio (P=0.007). Serum chemerin neither related to the insulinogenic index IGI_ins nor the disposition index. In conclusion, circulating chemerin is likely linked to enhanced beta cell function but not to insulin sensitivity in patients with NAFLD.

Evidence for a direct effect of the NAD+ precursor acipimox on muscle mitochondrial function in humans

Recent preclinical studies showed the potential of nicotinamide adenine dinucleotide (NAD(+)) precursors to increase oxidative phosphorylation and improve metabolic health, but human data are lacking. We hypothesize that the nicotinic acid derivative acipimox, an NAD(+) precursor, would directly affect mitochondrial function independent of reductions in nonesterified fatty acid (NEFA) concentrations. In a multicenter randomized crossover trial, 21 patients with type 2 diabetes (age 57.7 ± 1.1 years, BMI 33.4 ± 0.8 kg/m(2)) received either placebo or acipimox 250 mg three times daily dosage for 2 weeks. Acipimox treatment increased plasma NEFA levels (759 ± 44 vs. 1,135 ± 97 μmol/L for placebo vs. acipimox, P < 0.01) owing to a previously described rebound effect. As a result, skeletal muscle lipid content increased and insulin sensitivity decreased. Despite the elevated plasma NEFA levels, ex vivo mitochondrial respiration in skeletal muscle increased. Subsequently, we showed that acipimox treatment resulted in a robust elevation in expression of nuclear-encoded mitochondrial gene sets and a mitonuclear protein imbalance, which may indicate activation of the mitochondrial unfolded protein response. Further studies in C2C12 myotubes confirmed a direct effect of acipimox on NAD(+) levels, mitonuclear protein imbalance, and mitochondrial oxidative capacity. To the best of our knowledge, this study is the first to demonstrate that NAD(+) boosters can also directly affect skeletal muscle mitochondrial function in humans.

Modulation of amino acid metabolic signatures by supplemented isoenergetic diets differing in protein and cereal fiber content

CONTEXT

Amino-acid (AA) metabolic signatures differ in insulin-resistant (IR) obese vs normal-weight subjects, improve after weight loss, and seem to predict the risk of type 2 diabetes. It is unknown whether weight-maintaining dietary measures aimed at influencing IR alter AA signatures of high-risk subjects.

SETTING AND DESIGN

In the randomized controlled Protein, Fiber and Metabolic Syndrome (ProFiMet) trial we investigated effects of four isoenergetic, moderately fat-reduced diets varying in protein and cereal-fiber contents on complete AA metabolic signatures in 76 group-matched overweight or obese high-risk subjects. We analyzed the relation of whole-body and hepatic IR with AA signatures, body fat composition and liver fat, after 0, 6, and 18 weeks of dietary intervention. Discrimination between diets was further enhanced by providing tailored dietary supplements for twice-daily consumption over 18 weeks in all groups.

RESULTS

Baseline AA, including branched-chain signatures significantly related to IR, liver fat, and visceral fat mass. Isoenergetic variation of protein and cereal-fiber dietary contents, but not fat restriction, significantly influenced IR, whereas the relation of AA with IR changed with all diets. The tryptophan ratio was significantly suppressed in obese vs overweight participants, but increased after 6 weeks of high cereal-fiber intake to a nonobese phenotype. Modeling analyses revealed diet-induced alterations of complex AA profiles to relate to 70% and 62% of changes in whole-body and hepatic IR.

CONCLUSIONS

We demonstrate that relatively short-term isoenergetic changes in the diet significantly alter the relation of AA signatures with IR, with possible implications on the determination and treatment of diabetes risk.

Tissue-specific differences in the development of insulin resistance in a mouse model for type 1 diabetes

Although insulin resistance is known to underlie type 2 diabetes, its role in the development of type 1 diabetes has been gaining increasing interest. In a model of type 1 diabetes, the nonobese diabetic (NOD) mouse, we found that insulin resistance driven by lipid- and glucose-independent mechanisms is already present in the liver of prediabetic mice. Hepatic insulin resistance is associated with a transient rise in mitochondrial respiration followed by increased production of lipid peroxides and c-Jun N-terminal kinase activity. At the onset of diabetes, increased adipose tissue lipolysis promotes myocellular diacylglycerol accumulation. This is paralleled by increased myocellular protein kinase C θ activity and serum fetuin A levels. Muscle mitochondrial oxidative capacity is unchanged at the onset but decreases at later stages of diabetes. In conclusion, hepatic and muscle insulin resistance manifest at different stages and involve distinct cellular mechanisms during the development of diabetes in the NOD mouse.

Inhibition of 11β-HSD1 with RO5093151 for non-alcoholic fatty liver disease: a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND

The prevalence of non-alcoholic fatty liver disease is increasing worldwide and an effective and safe pharmacological treatment is needed. We investigated whether inhibition of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1, also known as HSD11B1) by RO5093151 could safely and effectively decrease liver-fat content in patients with this disorder.

METHODS

We did this phase 1b trial at four centres in Germany and Austria. Participants with non-alcoholic fatty liver disease (defined as (1)H magnetic resonance spectroscopy liver-fat content >5·56%), insulin resistance (homoeostatic model assessment of insulin resistance [HOMA-IR] of at least 2·0 mmol/L·mU/L), BMI greater than 27 kg/m(2), and aged 35-65 years were randomly assigned by interactive voice response system in a 1:1 ratio, stratified for triglyceride concentration (<1·7 mmol/L or ≥1·7 mmol/L), to oral RO5093151 (200 mg twice daily) or matching placebo for 12 weeks. The main exclusion criteria were other liver diseases, aspartate aminotransferase or alanine aminotransferase concentrations of more than two and a half times the upper limit of normal, history of diabetes or bariatric surgery, and use of weight lowering drugs. Participants and investigators were masked to assignment throughout the study. The primary endpoint was change in liver-fat content from baseline to week 12. Efficacy analysis was by modified intention to treat, including all patients who received at least one dose of study drug and had a baseline and follow-up measurement of liver-fat content. Safety analyses included all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT01277094.

FINDINGS

We did this trial between Jan 13, 2011, and March 28, 2012. 41 patients were randomly assigned to RO5093151 and 41 to placebo. 35 patients in the RO5093151 group and 39 in the placebo group were included in the efficacy analysis. Mean liver-fat content decreased in the RO5093151 group (from 16·75% [SD 8·67] to 14·28% [8·89]), but not in the placebo group (from 18·53% [10·00] to 18·46% [10·78], p=0·02 for between group difference). 26 participants (65%) in the RO5093151 group had adverse events, compared with 21 (53%) in the placebo group. The most common adverse events were gastrointestinal disorders (12 patients [30%] in the RO5093151 group vs seven [18%] in the placebo group), and infections and infestations (eight [20%] vs nine [23%]). Nervous system disorders occurred in significantly more patients in the RO5093151 group than in the placebo group (nine [23%] vs two [5%]; p=0·02); all other differences in adverse events were non-significant. One participant (3%) in the placebo group and three participants (8%) in the RO5093151 group had serious adverse events. All serious adverse events were deemed unrelated to study treatment.

INTERPRETATION

Inhibition of 11β-HSD1 by RO5093151 was effective and safe in reducing liver-fat content, suggesting that targeting of 11β-HSD1 might be a promising approach for the treatment of non-alcoholic fatty liver disease.

FUNDING

F Hoffmann-La Roche.

Reduction of non-esterified fatty acids improves insulin sensitivity and lowers oxidative stress, but fails to restore oxidative capacity in type 2 diabetes: a randomised clinical trial

AIMS/HYPOTHESIS

Muscle mitochondrial function can vary during fasting, but is lower during hyperinsulinaemia in insulin-resistant humans. Ageing and hyperlipidaemia may be the culprits, but the mechanisms remain unclear. We hypothesised that (1) insulin would fail to increase mitochondrial oxidative capacity in non-diabetic insulin-resistant young obese humans and in elderly patients with type 2 diabetes and (2) reducing NEFA levels would improve insulin sensitivity by raising oxidative capacity and lowering oxidative stress.

METHODS

Before and after insulin (4, 40, 100 nmol/l) stimulation, mitochondrial oxidative capacity was measured in permeabilised fibres and isolated mitochondria using high-resolution respirometry, and H2O2 production was assessed fluorimetrically. Tissue-specific insulin sensitivity was measured with hyperinsulinaemic-euglycaemic clamps combined with stable isotopes. To test the second hypothesis, in a 1-day randomised, crossover study, 15 patients with type 2 diabetes recruited via local advertisement were assessed for eligibility. Nine patients fulfilled the inclusion criteria (BMI <35 kg/m(2); age <65 years) and were allocated to and completed the intervention, including oral administration of 750 mg placebo or acipimox. Blinded randomisation was performed by the pharmacy; all participants, researchers performing the measurements and those assessing study outcomes were blinded. The main outcome measures were insulin sensitivity, oxidative capacity and oxidative stress.

RESULTS

Insulin sensitivity and mitochondrial oxidative capacity were ~31% and ~21% lower in the obese groups than in the lean group. The obese participants also exhibited blunted substrate oxidation upon insulin stimulation. In the patients with type 2 diabetes, acipimox improved insulin sensitivity by ~27% and reduced H2O2 production by ~45%, but did not improve basal or insulin-stimulated mitochondrial oxidative capacity. No harmful treatment side effects occurred.

CONCLUSIONS/INTERPRETATION

Decreased mitochondrial oxidative capacity can also occur independently of age in insulin-resistant young obese humans. Insulin resistance is present at the muscle mitochondrial level, and is not affected by reducing circulating NEFAs in type 2 diabetes. Thus, impaired plasticity of mitochondrial function is an intrinsic phenomenon that probably occurs independently of lipotoxicity and reduced glucose uptake.

TRIAL REGISTRATION

Clinical Trials NCT00943059 FUNDING: This study was funded in part by a grant from the German Federal Ministry of Education and Research to the German Center for Diabetes Research (DZD e.V.).

Effects of pioglitazone versus glimepiride exposure on hepatocellular fat content in type 2 diabetes

AIMS

Thiazoledinediones decrease blood glucose by their insulin-sensitizing properties. Here, we examined whether pioglitazone plus nateglinide (PIO) interferes with hepatocellular lipid (HCL) content and/or improves insulin sensitivity in well-controlled non-obese patients with type 2 diabetes mellitus (T2DM).

METHODS

Sixteen patients [body mass index (BMI): 28 ± 1 kg/m(2) ; HbA1c: 7.1 ± 0.6%] were studied in a randomized, double-blind, 12-week parallel group trial, whereas matched healthy humans [non-diabetic control subjects (CON), BMI: 26 ± 1 kg/m(2)] were studied once. Treatment with pioglitazone (30 mg/day) plus nateglinide (PIO arm) to control for glimepiride-induced insulin secretion was compared to treatment with glimepiride (2 mg/day) plus placebo (GLI arm). Multinuclei magnetic resonance spectroscopy (MRS) was combined with pancreatic normoglycaemic-two-step-insulin clamps and stable isotopes to assess glucose turnover, glucose transport/phosphorylation, HCL and intramyocellular lipid (IMCL) contents, non-esterified fatty acids (NEFA) and adipokines.

RESULTS

At baseline, HCL was approximately 5.6-fold higher in T2DM (p < 0.05 vs. CON). This was paralleled by approximately doubled leptin : adiponectin ratios (p < 0.05). HCL decreased by approximately 39% (p < 0.05) after PIO and only tended to decrease after GLI (p = 0.12). Treatment with PIO did not affect leptin : adiponectin ratios, but slightly improved (p < 0.05) insulin-mediated NEFA suppression, which related to lower HCL. PIO further prevented the insulin-induced increase in IMCL content of soleus and tibialis anterior muscles. Peripheral and hepatic insulin sensitivity, glucose transport and glycaemic control did not change in both groups.

CONCLUSION

Short-term, low-dose thiazolidendione treatment improves insulin sensitivity of lipolysis and HCL, without affecting muscle and liver insulin sensitivity. It appears that metabolic PIO action in T2DM is primarily mediated via a decline in HCL associated with greater sensitivity of lipolysis to insulin.

Lipid-induced insulin resistance is not mediated by impaired transcapillary transport of insulin and glucose in humans

Increased lipid availability reduces insulin-stimulated glucose disposal in skeletal muscle, which is generally explained by fatty acid-mediated inhibition of insulin signaling. It remains unclear whether lipids also impair transcapillary transport of insulin and glucose, which could become rate controlling for glucose disposal. We hypothesized that lipid-induced insulin resistance is induced by inhibiting myocellular glucose uptake and not by interfering with the delivery of insulin or glucose. We measured changes in interstitial glucose and insulin in skeletal muscle of healthy volunteers during intravenous administration of triglycerides plus heparin or glycerol during physiologic and supraphysiologic hyperinsulinemia, by combining microdialysis with oral glucose tolerance tests and euglycemic-hyperinsulinemic clamps. Lipid infusion reduced insulin-stimulated glucose disposal by ~70% (P < 0.05) during clamps and dynamic insulin sensitivity by ~12% (P < 0.05) during oral glucose loading. Dialysate insulin and glucose levels were unchanged or even transiently higher (P < 0.05) during lipid than during glycerol infusion, whereas regional blood flow remained unchanged. These results demonstrate that short-term elevation of free fatty acids (FFAs) induces insulin resistance, which in skeletal muscle occurs primarily at the cellular level, without impairment of local perfusion or transcapillary transport of insulin and glucose. Thus, vascular effects of FFAs are not rate controlling for muscle insulin-stimulated glucose disposal.

Production Rates of Cortisol in Obesity

OBJECTIVE

To determine the metabolic clearance rates (MCRs) and endogenous production rates (PRs) of cortisol (F) in grades 2 and 3 obese men (n = 9) and women (n = 6).

RESEARCH METHODS AND PROCEDURES

The MCRs and the endogenous PRs of cortisol (F) were determined in grades 2 and 3 obese men (n = 9) and women (n = 6) using the stable isotope dilution technique and mass spectrometry.

RESULTS

In obese women, endogenous PRs of F (0.6 +/- 0.4 mg/h) were similar to those of nonobese women, but MCRs of F were higher in obese women (9 +/- 4 L/h) compared with nonobese women (5 + 2 L/h; p < 0.05). The MCR of F was correlated with the ratio of excreted cortisone to F metabolites. Furthermore, obese women were characterized by an increased ratio of androsterone to etiocholanolone (p < 0.01). In obese men, the MCRs (11 +/- 6 L/h) and the endogenous PRs of F (0.6 +/- 0.3 mg/h) were both similar to those of nonobese men, but the MCR of F was directly correlated with the ratio of excreted cortisone to F metabolites (r = 0.7833, p = 0.012).

DISCUSSION

These data demonstrate sex-specific differences in F metabolism in obesity. The rise in MCRs of F is more pronounced in obese women than in men. However, the increase in the MCR of F is moderate in both genders and exceeds the normal range only in a subgroup of obese individuals.

Quantifying the improvement of surrogate indices of hepatic insulin resistance using complex measurement techniques

We evaluated the ability of simple and complex surrogate-indices to identify individuals from an overweight/obese cohort with hepatic insulin-resistance (HEP-IR). Five indices, one previously defined and four newly generated through step-wise linear regression, were created against a single-cohort sample of 77 extensively characterised participants with the metabolic syndrome (age 55.6±1.0 years, BMI 31.5±0.4 kg/m²; 30 males). HEP-IR was defined by measuring endogenous-glucose-production (EGP) with [6–6²H₂] glucose during fasting and euglycemic-hyperinsulinemic clamps and expressed as EGP*fasting plasma insulin. Complex measures were incorporated into the model, including various non-standard biomarkers and the measurement of body-fat distribution and liver-fat, to further improve the predictive capability of the index. Validation was performed against a data set of the same subjects after an isoenergetic dietary intervention (4 arms, diets varying in protein and fiber content versus control). All five indices produced comparable prediction of HEP-IR, explaining 39–56% of the variance, depending on regression variable combination. The validation of the regression equations showed little variation between the different proposed indices (r² = 27–32%) on a matched dataset. New complex indices encompassing advanced measurement techniques offered an improved correlation (r = 0.75, P<0.001). However, when validated against the alternative dataset all indices performed comparably with the standard homeostasis model assessment for insulin resistance (HOMA-IR) (r = 0.54, P<0.001). Thus, simple estimates of HEP-IR performed comparable to more complex indices and could be an efficient and cost effective approach in large epidemiological investigations.

Effects of supplemented isoenergetic diets differing in cereal fiber and protein content on insulin sensitivity in overweight humans

BACKGROUND

Despite their beneficial effects on weight loss and blood lipids, high-protein (HP) diets have been shown to increase insulin resistance and diabetes risk, whereas high-cereal-fiber (HCF) diets have shown the opposite effects on these outcomes.

OBJECTIVE

We compared the effects of isoenergetic HP and HCF diets and a diet with moderate increases in both cereal fibers and dietary protein (Mix diet) on insulin sensitivity, as measured by using euglycemic-hyperinsulinemic clamps with infusion of [6,6-(2)H(2)]glucose.

DESIGN

We randomly assigned 111 overweight adults with features of the metabolic syndrome to 1 of 4 two-phased, 18-wk isoenergetic diets by group-matching. Per 3-d food protocols, the percentages of energy derived from protein and carbohydrates and the intake of cereal fiber per day, respectively, were as follows-after 6 wk: 17%, 52%, and 14 g (control); 17%, 52%, and 43 g (HCF); 28%, 43%, and 13 g (HP); 23%, 44%, and 26 g (Mix); after 18 wk: 17%, 51%, and 15 g (control); 17%, 51%, and 41 g (HCF); 26%, 45%, and 14 g (HP); and 22%, 46%, and 26 g (Mix). Eighty-four participants completed the study successfully and were included in the final analyses. Adherence was supported by the provision of tailored dietary supplements twice daily in all groups.

RESULTS

Insulin sensitivity expressed as an M value was 25% higher after 6 wk of the HCF diet than after 6 wk of the HP diet (subgroup analysis: 4.61 ± 0.38 compared with 3.71 ± 0.36 mg · kg(-1) · min(-1), P = 0.008; treatment × time interaction: P = 0.005). Effects were attenuated after 18 wk (treatment × time interaction: P = 0.054), which was likely explained by lower adherence to the HP diet. HP intake was associated with a tendency to increased protein expression in adipose tissue of the translation initiation factor serine-kinase-6-1, which is known to mediate amino acid-induced insulin resistance. Biomarkers of protein intake indicated interference of cereal fibers with dietary protein absorption.

CONCLUSION

Greater changes in insulin sensitivity after intake of an isoenergetic HCF than after intake of an HP diet might help to explain the diverse effects of these diets on diabetes risk. This trial is registered at clinicaltrials.gov as NCT00579657.

Postprandial and fasting hepatic glucose fluxes in long-standing type 1 diabetes

OBJECTIVE

Intravenous insulin infusion partly improves liver glucose fluxes in type 1 diabetes (T1D). This study tests the hypothesis that continuous subcutaneous insulin infusion (CSII) normalizes hepatic glycogen metabolism.

RESEARCH DESIGN AND METHODS

T1D with poor glycemic control (T1Dp; HbA(1c): 8.5 ± 0.4%), T1D with improved glycemic control on CSII (T1Di; 7.0 ± 0.3%), and healthy humans (control subjects [CON]; 5.2 ± 0.4%) were studied. Net hepatic glycogen synthesis and glycogenolysis were measured with in vivo (13)C magnetic resonance spectroscopy. Endogenous glucose production (EGP) and gluconeogenesis (GNG) were assessed with [6,6-(2)H(2)]glucose, glycogen phosphorylase (GP) flux, and gluconeogenic fluxes with (2)H(2)O/paracetamol.

RESULTS

When compared with CON, net glycogen synthesis was 70% lower in T1Dp (P = 0.038) but not different in T1Di. During fasting, T1Dp had 25 and 42% higher EGP than T1Di (P = 0.004) and CON (P < 0.001; T1Di vs. CON: P = NS). GNG was 74 and 67% higher in T1Dp than in T1Di (P = 0.002) and CON (P = 0.001). In T1Dp, GP flux (7.0 ± 1.6 μmol ⋅ kg(-1) ⋅ min(-1)) was twofold higher than net glycogenolysis, but comparable in T1Di and CON (3.7 ± 0.8 and 4.9 ± 1.0 μmol ⋅ kg(-1) ⋅ min(-1)). Thus T1Dp exhibited glycogen cycling (3.5 ± 2.0 μmol ⋅ kg(-1) ⋅ min(-1)), which accounted for 47% of GP flux.

CONCLUSIONS

Poorly controlled T1D not only exhibits augmented fasting gluconeogenesis but also increased glycogen cycling. Intensified subcutaneous insulin treatment restores these abnormalities, indicating that hepatic glucose metabolism is not irreversibly altered even in long-standing T1D.

Impaired insulin stimulation of muscular ATP production in patients with type 1 diabetes

OBJECTIVE

in type 2 diabetic patients and their first-degree relatives, insulin resistance (IR) is associated with impairment of insulin-stimulated myocellular glucose-6-phosphate (g6p) and unidirectional flux through ATP synthase (fATP), suggesting the presence of inherited abnormal mitochondrial oxidative fitness. We hypothesized that patients with long-standing type 1 diabetes may also exhibit insulin resistance as well as lower fATP.

DESIGN

this single-centre trial was registered at ClinicalTrials.gov (NCT00481598).

SUBJECTS

we included eight nonobese type 1 diabetic patients (mean diabetes duration: 17 years) with near-target glycaemic control [haemoglobin A1c (HbA1c): 6.8 ± 0.4%] during treatment with continuous subcutaneous insulin infusion pumps and eight healthy volunteers (HbA1c: 5.4 ± 0.2%) of comparable age, body mass and level of physical activity.

OUTCOME MEASURES

myocellular fATP, g6p and intramyocellular lipid content (IMCL) were measured with (1) H/(31) P magnetic resonance spectroscopy during fasting and hyperinsulinaemic-euglycaemic clamp tests.

RESULTS

fasting fATP, g6p and IMCL did not differ between groups. During stimulation by insulin, type 1 diabetic patients exhibited approximately 50% (P < 0.001) lower whole-body glucose disposal along with approximately 42% (P = 0.003) lower intramyocellular g6p and approximately25% (P = 0.024) lower fATP. Insulin-stimulated fATP correlated positively with whole-body insulin sensitivity (R = 0.706, P = 0.002) and negatively with HbA1c (R = -0.675, P = 0.004).

CONCLUSIONS

despite documented near-target glycaemic control for 1 year, nonobese patients with long-standing type 1 diabetes can exhibit insulin resistance. This associates with lower insulin-stimulated flux through muscular ATP synthase which could result from glucose toxicity.

Acute elevation of plasma lipids does not affect ATP synthesis in human skeletal muscle

Prolonged elevation of plasma triglycerides and free fatty acids (FFA) reduces insulin-stimulated glucose disposal and myocellular flux through ATP synthase (fATPase). However, the early effects of lipids per se on fATPase are as yet unclear. Thus, this study examined glucose disposal and fATPase during 3 h of FFA elevation in the presence of low plasma insulinemia. Euglycemic pancreatic clamps with low-dose insulin supplementation (6 mU.m body surface area(-2).min(-1)) were performed in eight healthy men with (LIP) or without (CON) lipid infusion to measure whole body glucose disposal. (31)P/(1)H magnetic resonance spectroscopy of calf muscle was applied to quantify fATPase and concentrations of glucose 6-phosphate (G6P), inorganic phosphate (P(i)), phosphocreatine (PCr), ADP, pH, and IMCL before and during the clamps. Lipid infusion increased plasma FFA approximately twofold and decreased glucose disposal by approximately 50% (110-180 min: LIP 0.87 +/- 0.45 vs. CON 1.75 +/- 0.42 mg.kg(-1).min(-1), P = 0.002; means +/- SD). Intramyocellular G6P tended to rise only under control conditions, whereas PCr, ADP, pH, and IMCL remained unchanged from fasting in LIP and CON. Although P(i) concentrations increased by approximately 18%, fATPase remained unchanged from fasting during the clamps (LIP 10.2 +/- 2.2 vs. CON 10.5 +/- 2.6 micromol.g muscle(-1).min(-1), P = not significant). We conclude that 3 h of lipid elevation fail to affect ATP synthesis despite marked reduction of whole body glucose uptake. This suggests that lipid-induced insulin resistance results primarily from mechanisms decreasing glucose uptake rather than from direct interference of fatty acid metabolites with mitochondrial function.

Adipokines in type 1 diabetes after successful pancreas transplantation: normal visfatin and retinol-binding-protein-4, but increased total adiponectin fasting concentrations

OBJECTIVE

In type 1 diabetes mellitus (T1DM), the release of many hormones, not only from beta-cells, but also from adipocytes (adipokines) may be altered. After successful pancreas-kidney-transplantation (PKTx), T1DM patients can revert to a nondiabetic metabolism, but it is unclear whether alterations of adipokines are still present after PKTx.

DESIGN, PATIENTS AND MEASUREMENTS

Concentrations of adipokines [visfatin, retinol-binding protein-4 (RBP-4), adiponectin, high molecular weight (HMW) adiponectin] were measured at fasting in 10 PKTx and in 19 T1DM. Nondiabetic healthy controls (CON, n = 9) and six nondiabetic patients after kidney transplantation (KTx) were examined as control groups. In PKTx, KTx and CON, indices of insulin sensitivity (OGIS) and beta cell function (adaptation index, AI) were calculated from 75 g oral glucose tolerance test (OGTT) data.

RESULTS

Fasting serum visfatin (T1DM: 56 +/- 4 microg/l, PKTx: 42 +/- 6 microg/l, KTx: 39 +/- 3 microg/l, CON: 40 +/- 3 microg/l) and RBP-4 (T1DM: 490 +/- 26 microg/l, PKTx: 346 +/- 39 microg/l, KTx: 401 +/- 13 microg/l, CON: 359 +/- 36 microg/l) was increased by 40% and 36%, respectively (each P < 0.03) in T1DM only. Levels were positively correlated with HbA1c in all subjects (visfatin: r = 0.43, P < 0.004; RBP-4: r = 0.46, P < 0.03). Fasting plasma adiponectin was 80% higher in T1DM and in PKTx (T1DM: 18 +/- 2 mg/l, PKTx: 18 +/- 3 mg/l, KTx: 12 +/- 3 mg/l, CON: 10 +/- 1 mg/l; P < 0.04) and was positively correlated with diabetes duration (r = 0.37, P < 0.02). HMW/total adiponectin ratio was increased in T1DM (P < 0.02). PKTx displayed a normoglycaemic metabolism as insulin sensitive as CON, but AI was lower than in CON and KT (P < 0.01).

CONCLUSIONS

T1DM after successful PKTx show normal fasting visfatin and RBP-4 levels and HMW-adiponectin/adiponectin-ratio, which are elevated in T1DM, whereas total adiponectin levels are similarly increased in T1DM and PKTx patients.

Chronic peripheral hyperinsulinemia in type 1 diabetic patients after successful combined pancreas-kidney transplantation does not affect ectopic lipid accumulation in skeletal muscle and liver

OBJECTIVE

So far it is unclear whether chronic peripheral hyperinsulinemia per se might contribute to ectopic lipid accumulation and consequently insulin resistance. We investigated the effects of systemic instead of portal insulin release in type 1 diabetic patients after successful pancreas-kidney transplantation (PKT) with systemic venous drainage on the intracellular lipid content in liver and soleus muscle, endogenous glucose production (EGP), and insulin sensitivity.

RESEARCH DESIGN AND METHODS

In nine PKT patients and nine matching nondiabetic control subjects, intrahepatocellular lipids (IHCLs) and intramyocellular lipids (IMCLs) were measured using (1)H nuclear magnetic resonance spectroscopy. Fasting EGP was measured using d-[6,6-(2)H(2)]glucose tracer dilution. A 3-h 75-g oral glucose tolerance test (OGTT) allowed us to assess kinetics of glucose, free fatty acids, insulin, and C-peptide concentrations in plasma and to calculate the clamp-like index (CLIX) for insulin sensitivity and the hepatic insulin resistance (HIR) index.

RESULTS

The PKT patients displayed approximately twofold increased fasting insulin (20 +/- 6 vs. 9 +/- 3 microU/ml; P < 0.0002) compared with that in nondiabetic control subjects and approximately 10% increased fasting glucose (P < 0.02) concentrations, but during the OGTT areas under the concentration curves of C-peptide and insulin were similar. IHCL (PKT, 2.9 +/- 2.5%; nondiabetic control subjects, 4.4 +/- 6.6%), IMCL (PKT, 1.0 +/- 0.4%; nondiabetic control subjects, 1.0 +/- 0.5%), CLIX (PKT, 8 +/- 2; nondiabetic control subjects, 7 +/- 3), HIR (PKT, 25.6 +/- 13.2; nondiabetic control subjects, 35.6 +/- 20 [mg * min(-1) * kg(-1)] x [microU/ml]), and EGP (PKT, 1.6 +/- 0.2; nondiabetic control subjects, 1.7 +/- 0.2 mg * min(-1) * kg(-1)) were comparable between PKT patients and nondiabetic control subjects. IHCL was negatively correlated with CLIX in all participants (r = -0.55; P < 0.04).

CONCLUSIONS

Despite fasting peripheral hyperinsulinemia because of systemic venous drainage, type 1 diabetic patients after PKT show similar IHCL, IMCL, insulin sensitivity, and fasting EGP in comparison with nondiabetic control subjects. These results suggest that systemic hyperinsulinemia per se does not cause ectopic lipid accumulation in liver and skeletal muscle.