Does exercise affect the antioxidant system in patients with ankylosing spondylitis?

We aimed to investigate the effect of regular supervised exercise program on functinal status, disease activity, and total antioxidant status (TAS) level in patients with ankylosing spondylitis (AS). Thirty-two patients (mean age: 44 years) with AS were included in the study and divided into two groups. Group 1, the exercise group (n = 16), attended a supervised exercise program that consisted of aerobic, strengthening, and stretching exercises for 1 h a day, five times a week for 3 weeks. Group 2, the control group, received a home exercise program (n:16). Bath AS Activity Index (BASDAI) and Bath AS Functional Index (BASFI) were calculated and serum TAS levels were measured for each patient at 0 and 3 weeks. There was no significant difference in patients' baseline characteristics (age, disease duration, BASFI, and BASDAI scores) between exercise and control groups. In the exercise group, there were significant improvements between pre-exercise and post-exercise assessments in BASFI (2.8 ± 1,8; 1.7 ± 1,40, p = 0.004) and BASDAI scores (2.1 ± 1.7; 1.2 ± 1.3, p = 0.01). Mean TAS levels were significantly decreased after supervised exercise program (1.48 ± 0.16 mmol/L; 1.36 ± 0.20 mmol/L, p = 0.03). In the control group, BASFI score (2.4 ± 1.7; 2.9 ± 2.1, p = 0.19), BASDAI score (2.6 ± 2.2; 3.1 ± 2.6, p = 0.33), and mean TAS levels (1.38 ± 0.23 mmol/L; 1.39 ± 0.20 mmol/L, p = 0.66) did not differ significantly between 0 and 3 weeks. Short-term, supervised exercise program improved functional status and decreased disease activity. However, the mechanism of this beneficial clinical effect does not seem to be through antioxidant activity.     

Evidence for abnormal glucose uptake or metabolism in thalamus during acute hyperglycaemia in type 1 diabetes—a <Superscript>1</Superscript>H MRS study

Acute hyperglycaemia impairs cognitive function. It is however not known, whether different brain regions are equally exposed to glucose during acute hyperglycemia or whether the brain is able to adjust its glucose uptake or metabolism in response to blood glucose fluctuation. We studied the effect of acute hyperglycaemia on the brain glucose concentration in seven men with type 1 diabetes with daily glucose fluctuations of 11 ± 3 mmol/l, and in eleven age-matched non-diabetic men. Glucose was quantified with proton magnetic resonance spectroscopy in three different brain regions at baseline (fasting glycaemia) and twice during a 2 h hyperglycaemic clamp with plasma glucose increase of 12 mmol/l. The increase in brain glucose during acute hyperglycaemia in the non-diabetic group was: cortex (2.7 ± 0.9 mmol/l) > thalamus (2.3 ± 0.7 mmol/l) > white matter (1.7 ± 0.7 mmol/l, P = 0.021 vs. cortex) and in the diabetic group: cortex (2.0 ± 0.7 mmol/l) > white matter (1.3 ± 0.7 mmol/l) > thalamus (1.1 ± 0.4 mmol/l, P = 0.010 vs. cortex). In the diabetic group, the glucose increase in the thalamus was attenuated compared to the non-diabetic participants (P = 0.011). In conclusion, the increase of glucose during acute hyperglycaemia seems to be dependent on the brain tissue type. The high exposure of cortex to excess glucose and the altered glucose uptake or metabolism in the thalamus may thus contribute to hyperglycaemia related cognitive dysfunction.     

A comparison of twice-daily exenatide and biphasic insulin aspart in patients with type 2 diabetes who were suboptimally controlled with sulfonylurea and metformin: a non-inferiority study

Aims/hypothesis The aim of this 52-week, open-label, non-inferiority trial was to compare the safety and efficacy of exenatide (an incretin mimetic) with that of biphasic insulin aspart. Materials and methods Patients on metformin and a sulfonylurea were randomised to exenatide (n = 253; 5 μg twice daily for 4 weeks, 10 μg thereafter) or biphasic insulin aspart (n = 248; twice-daily doses titrated for optimal glucose control), while continuing with metformin and sulfonylurea treatment. Results Glycaemic control achieved with exenatide was non-inferior to that achieved with biphasic insulin aspart (mean±SEM, HbA_1c change: exenatide −1.04 ± 0.07%, biphasic insulin aspart −0.89 ± 0.06%; difference −0.15 [95% CI −0.32 to 0.01]%). Exenatide-treated patients lost weight, while patients treated with biphasic insulin aspart gained weight [between-group difference −5.4 (95% CI −5.9 to −5.0) kg]. Both treatments reduced fasting serum glucose (exenatide −1.8 ± 0.2 mmol/l, p < 0.001; biphasic insulin aspart −1.7 ± 0.2 mmol/l, p < 0.001). Greater reductions in postprandial glucose excursions following morning (p < 0.001), midday (p = 0.002) and evening meals (p < 0.001) were observed with exenatide. The withdrawal rate was 21.3% (54/253) for exenatide and 10.1% (25/248) for biphasic insulin aspart. Nausea (33% incidence, 3.5% discontinuation) was the most common adverse event observed with exenatide. Conclusions/interpretation Exenatide treatment resulted in HbA_1c reduction similar to biphasic insulin aspart and provided better postprandial glycaemic control, making it a potential alternative for the treatment of type 2 diabetes. Treatment with biphasic insulin aspart was associated with weight gain and lower risk of adverse gastrointestinal events. Although the availability of glucose-lowering agents associated with weight reduction may be considered a therapeutic advance, the long-term implications of progressive weight reduction observed with exenatide have yet to be defined. Electronic supplementary material A list of the site investigators is available as electronic supplementary material in the online version of this article at and is accessible to authorised users.     

Influence of gestational diabetes on the long-term control of glucose tolerance

Aims/hypothesis Gestational diabetes (GDM) carries a high risk of subsequent diabetes. We asked what impact prior GDM has on beta cell function and insulin action in women who maintain normal glucose tolerance (NGT) for a long time. Methods Ninety-one women with NGT (aged 41 ± 8 years, mean±SD) were studied (by mathematical modelling of the C-peptide response to an OGTT) 7 [6] years (median [interquartile range]) after the index pregnancy, during which 52 had GDM (pGDM) and 39 had NGT (pNGT). In all women an OGTT had also been performed at 29 ± 3 weeks of the index pregnancy. Results Women with pGDM were matched with women with pNGT for age, familial diabetes, time and weight gain since index pregnancy, parity, BMI (25.4 ± 3.9 vs 26.8 ± 6.4 kg/m²), and fasting (4.64 ± 0.56 vs 4.97 ± 0.46 mmol/l) and 2 h plasma glucose levels (5.91 ± 1.14 vs 5.91 ± 1.21 mmol/l). Nonetheless, fasting (49 [29] vs 70 [45] pmol min⁻¹ m⁻², p < 0.001) and total insulin secretion (32 [17] vs 48 [21] nmol m⁻², p < 0.0001) and beta cell glucose sensitivity (slope of the insulin secretion/plasma glucose concentration–response function) (95 [71] vs 115 [79] pmol min⁻¹ m⁻² (mmol/l)⁻¹, p = 0.025) were reduced in the pGDM group compared with the pNGT group, while insulin sensitivity was preserved (424 [98] vs 398 [77] ml min⁻¹ m⁻²). At index pregnancy, women with pGDM and those with pNGT had similar age and BMI. However, both insulin sensitivity (359 [93] vs 417 [92] ml min⁻¹ m⁻², p = 0.0012) and the insulin/glucose incremental area ratio (an empirical index of beta cell function; 98 [74] vs 138 [122] pmol/mmol, p = 0.028) were reduced in women with pGDM. Conclusions Even in women who maintain normal insulin sensitivity, impaired beta cell function is carried over into the NGT status several years after a GDM pregnancy.     

Glucagon receptor antagonism improves islet function in mice with insulin resistance induced by a high-fat diet

Aims/hypothesis Increased glucagon secretion predicts deterioration of glucose tolerance, and high glucagon levels contribute to hyperglycaemia in type 2 diabetes. Inhibition of glucagon action may therefore be a potential novel target to reduce hyperglycaemia. Here, we investigated whether chronic treatment with a glucagon receptor antagonist (GRA) improves islet dysfunction in female mice on a high-fat diet (HFD). Materials and methods After 8 weeks of HFD, mice were treated with a small molecule GRA (300 mg/kg, gavage once daily) for up to 30 days. Insulin secretion was studied after oral and intravenous administration of glucose and glucagon secretion after intravenous arginine. Islet morphology was examined and insulin secretion and glucose oxidation were measured in isolated islets. Results Fasting plasma glucose levels were reduced by GRA (6.0 ± 0.2 vs 7.4 ± 0.5 mmol/l; p = 0.017). The acute insulin response to intravenous glucose was augmented (1,300 ± 110 vs 790 ± 64 pmol/l; p < 0.001). The early insulin response to oral glucose was reduced in mice on HFD + GRA (1,890 ± 160 vs 3,040 ± 420 pmol/l; p = 0.012), but glucose excursions were improved. Intravenous arginine significantly increased the acute glucagon response (129 ± 12 vs 36 ± 6 ng/l in controls; p < 0.01), notably without affecting plasma glucose. GRA caused a modest increase in alpha cell mass, while beta cell mass was similar to that in mice on HFD + vehicle. Isolated islets displayed improved glucose-stimulated insulin secretion after GRA treatment (0.061 ± 0.007 vs 0.030 ± 0.004 pmol islet⁻¹ h⁻¹ at 16.7 mmol/l glucose; p < 0.001), without affecting islet glucose oxidation. Conclusions/interpretation Chronic glucagon receptor antagonism in HFD-fed mice improves islet sensitivity to glucose and increases insulin secretion, suggesting improvement of key defects underlying impaired glucose tolerance and type 2 diabetes.     

Omitting breakfast and lunch after injection of different long-acting insulin preparations at bedtime: a prospective study in patients with type 2 diabetes

Aims/hypothesis  The aim of this prospective trial was to compare the effect of different long-acting insulin preparations injected at bedtime on glucose concentrations in patients with type 2 diabetes omitting breakfast and lunch the next day. Methods  Twenty patients (ten women) with type 2 diabetes who were on an intensified insulin therapy participated. Mean (±SD) age was 63 ± 10 years, diabetes duration 18 ± 9 years, BMI 32.5 ± 5 kg/m², and HbA_1c 7.3 ± 0.7%. Patients received neutral protamine Hagedorn (NPH) insulin, insulin detemir or insulin glargine for at least 2 months; doses were adjusted to achieve morning blood glucose levels of <7 mmol/l. At the end of the respective treatment period, the long-acting insulin was injected at bedtime (at 22:45 hours) as usual but patients refrained from breakfast and lunch the next day; glucose was measured by a continuous glucose monitoring system (CGMS). Results   Comparable glucose target ranges were reached at midnight (5.8 to 6.1 mmol/l) and at 07:00 hours (6.7 to 6.9 mmol/l) with all three insulin preparations, using mean doses of 29 ± 10 U (NPH insulin), 33 ± 13 U (insulin detemir), and 32 ± 12 U (insulin glargine). Glucose levels between midnight and 07:00 hours were not significantly different for the three insulin preparations. Symptomatic hypoglycaemia did not occur from 08:00 to 16:00 hours; glucose concentrations during this time were slightly lower with NPH insulin than with insulin detemir (p = 0.012) and insulin glargine (p = 0.049). Conclusions/interpretation  Following bedtime injection of NPH insulin or of the analogues insulin detemir or insulin glargine, fasting glucose <7 mmol/l was achieved in the morning, without subsequent hypoglycaemia when participants continued to fast during the day.     

Patients with type 2 diabetes have normal mitochondrial function in skeletal muscle

Aims/hypothesis Insulin resistance and type 2 diabetes are associated with mitochondrial dysfunction. The aim of the present study was to test the hypothesis that oxidative phosphorylation and electron transport capacity are diminished in the skeletal muscle of type 2 diabetic subjects, as a result of a reduction in the mitochondrial content. Materials and methods The O₂ flux capacity of permeabilised muscle fibres from biopsies of the quadriceps in healthy subjects (n = 8; age 58 ± 2 years [mean±SEM]; BMI 28 ± 1 kg/m²; fasting plasma glucose 5.4 ± 0.2 mmol/l) and patients with type 2 diabetes (n = 11; age 62 ± 2 years; BMI 32 ± 2 kg/m²; fasting plasma glucose 9.0 ± 0.8 mmol/l) was measured by high-resolution respirometry. Results O₂ flux expressed per mg of muscle (fresh weight) during ADP-stimulated state 3 respiration was lower (p < 0.05) in patients with type 2 diabetes in the presence of complex I substrate (glutamate) (31 ± 2 vs 43 ± 3 pmol O₂ s⁻¹ mg⁻¹) and in response to glutamate + succinate (parallel electron input from complexes I and II) (63 ± 3 vs 85 ± 6 pmol s⁻¹ mg⁻¹). Further increases in O₂ flux capacity were observed in response to uncoupling by FCCP, but were again lower (p < 0.05) in type 2 diabetic patients than in healthy control subjects (86 ± 4 vs 109 ± 8 pmol s⁻¹ mg⁻¹). However, when O₂ flux was normalised for mitochondrial DNA content or citrate synthase activity, there were no differences in oxidative phosphorylation or electron transport capacity between patients with type 2 diabetes and healthy control subjects. Conclusions/interpretation Mitochondrial function is normal in type 2 diabetes. Blunting of coupled and uncoupled respiration in type 2 diabetic patients can be attributed to lower mitochondrial content.     

Evidence that autonomic mechanisms contribute to the adaptive increase in insulin secretion during dexamethasone-induced insulin resistance in humans

Aims/hypothesis This study examined whether autonomic mechanisms contribute to adaptively increased insulin secretion in insulin-resistant humans, as has been proposed from studies in animals. Methods Insulin secretion was evaluated before and after induction of insulin resistance with or without interruption of neural transmission. Insulin resistance was induced by dexamethasone (15 mg given over 3 days) in nine healthy women (age 67 years, BMI 25.2 ± 3.4 kg/m², fasting glucose 5.1 ± 0.4 mmol/l, fasting insulin 46 ± 6 pmol/l). Insulin secretion was evaluated as the insulin response to intravenous arginine (5 g) injected at fasting glucose and after raising glucose to 13 to15 mmol/l or to >28 mmol/l. Neural transmission across the ganglia was interrupted by infusion of trimethaphan (0.3–0.6 mg kg⁻¹ min⁻¹). Results As an indication of insulin resistance, dexamethasone increased fasting insulin (to 75 ± 8 pmol/l, p < 0.001) without significantly affecting fasting glucose. Arginine-induced insulin secretion was increased by dexamethasone at all glucose levels (by 64 ± 12% at fasting glucose, by 80 ± 19% at 13–15 mmol glucose and by 43 ± 12% at >28 mmol glucose; p <0.001 for all). During dexamethasone-induced insulin resistance, trimethaphan reduced the insulin response to arginine at all three glucose levels. The augmentation of the arginine-induced insulin responses by dexamethasone-induced insulin resistance was reduced by trimethaphan by 48 ± 6% at fasting glucose, 61 ± 8% at 13–15 mmol/l glucose and 62 ± 8% at >28 mmol/l glucose (p < 0.001 for all). In contrast, trimethaphan did not affect insulin secretion before dexamethasone was given. Conclusions/interpretations Autonomic mechanisms contribute to the adaptative increase in insulin secretion in dexamethasone-induced insulin resistance in healthy participants.     

Reducing glycaemic variability in type 1 diabetes self-management with a continuous glucose monitoring system based on wired enzyme technology

Aims/hypothesis  This study was designed to investigate the use and impact of a continuous glucose monitoring system (the FreeStyle Navigator) under home-use conditions in the self-management of type 1 diabetes. Methods  A 20 day masked phase, when real-time data and alarms were not available, was compared with a subsequent 40 day unmasked phase for a number of specified measures of glycaemic variability. HbA_1c (measured by DCA 2000) and a hypoglycaemia fear survey were recorded at the start and end of the study. Results  The study included 48 patients with type 1 diabetes (mean age 35.7 ± 10.9, range 18–61 years; diabetes duration 17.0 ± 9.5 years). Two patients did not complete the study for personal reasons. Comparing masked (all 20 days) and unmasked (last 20 days) phases, the following reductions were seen: time outside euglycaemia from 11.0 to 9.5 h/day (p = 0.002); glucose SD from 3.5 to 3.2 mmol/l (p < 0.001); hyperglycaemic time (>10.0 mmol/l) from 10.3 to 8.9 h/day (p = 0.0035); mean amplitude of glycaemic excursions (peak to nadir) down by 10% (p < 0.001); high blood glucose index down by 18% (p = 0.0014); and glycaemic risk assessment diabetes equation score down by 12% (p = 0.0013). Hypoglycaemic time (<3.9 mmol/l) decreased from 0.70 to 0.64 h/day without statistical significance (p > 0.05). Mean HbA_1c fell from 7.6 ± 1.1% at baseline to 7.1 ± 1.1% (p < 0.001). In the hypoglycaemia fear survey, the patients tended to take less snacks at night-time after wearing the sensor. Conclusions/interpretation  Home use of a continuous glucose monitoring system has a positive effect on the self-management of diabetes. Thus, continuous glucose monitoring may be a useful tool to decrease glycaemic variability.     

Tissue specificity of insulin resistance in humans: fat in the liver rather than muscle is associated with features of the metabolic syndrome

Aims/hypothesis The aim of this study was to investigate whether intrahepatic and intramyocellular fat are related to insulin resistance in these respective tissues or to the metabolic syndrome. Methods Hepatic (insulin 1.8 pmol kg⁻¹ min⁻¹ combined with [3-³H]glucose) and muscle (insulin 6.0 pmol kg⁻¹ min⁻¹) insulin sensitivity were measured on separate occasions in 45 non-diabetic men (age 42 ± 1 years, BMI 26.2 ± 0.6 kg/m²) using the euglycaemic–hyperinsulinaemic clamp. Liver fat and intramyocellular lipid (IMCL) were measured by proton magnetic resonance spectroscopy and body composition by magnetic resonance imaging. We also determined fasting serum insulin and adiponectin concentrations, components of the metabolic syndrome and maximal oxygen consumption. Results In participants with high [median 12.0% (interquartile range 5.7–18.5%)] vs low [2.0% (1.0–2.0%)] liver fat, fasting serum triacylglycerols (1.6 ± 0.2 vs 1.0 ± 0.1 mmol/l, p = 0.002) and fasting serum insulin (55 ± 4 vs 32 ± 2 pmol/l, p < 0.0001) were increased and serum HDL-cholesterol (1.26 ± 0.1 vs 1.48 ± 0.1 mmol/l, p = 0.02) and fasting serum adiponectin (9.5 ± 1.2 vs 12.2 ± 1.2 μg/ml, p = 0.05) decreased. In participants with high [19.5% (16.0–26.0%)] vs low [5.0% (2.3–7.5%)] IMCL, these parameters were comparable. Liver fat was higher in participants with [10.5% (3.0–18.0%)] than in those without [2.0% (1.5–6.0%), p = 0.010] the metabolic syndrome, even independently of obesity, while IMCL was comparable. Insulin suppression of glucose rate of appearance and serum NEFA was significantly impaired in the high liver fat group. Conclusions/interpretation Fat accumulation in the liver rather than in skeletal muscle is associated with features of the metabolic syndrome, i.e. increased fasting serum triacylglycerols and decreased fasting serum HDL-cholesterol, as well as with hyperinsulinaemia and low adiponectin.     

Lipid profile in Tunisian patients with rheumatoid arthritis

This study aims to assess the prevalence of dyslipidaemia in Tunisian patients with active RA and to investigate the clinical and biological associated factors. A cross-sectional study was conducted on 92 unselected patients with active RA (77 females and 15 males, aged 49.1 ± 12.5 years) and 82 healthy subjects (68 females and 14 males, aged 50.8 ± 13.3 years). We recorded the patients' characteristics and the results of a lipid profile test (total cholesterol, TC; high-density lipoprotein cholesterol, HDL-c; low-density lipoprotein cholesterol, LDL-c; triglyceride, TG; lipoprotein (a), Lp (a); apolipoprotein A-1, apo A-1 and apolipoprotein B, apo B). In comparison to the control group, RA patients showed a higher prevalence of associated dyslipidaemia (95.7% versus 65.9% of cases, p < 0.001). Sera of patients showed higher TC (4.86 ± 1.07 versus 3.98 ± 0.73 mmol/L, p < 0.001), LDL-c (3.49 ± 0.98 versus 1.99 ± 0.62 mmol/L, p < 0.001), Lp (a) (288.04 ± 254.59 versus 187.94 ± 181.37 mmol/L, p = 0.004) and lower HDL-c (0.66 ± 0.24 versus 1.12 ± 0.3 mmol/L, p < 0.001). TC/HDL-c, LDL-c/HDL-c and non-HDL-c/HDL-c were also higher in RA patients; they were 8.24 ± 3.20 versus 3.76 ± 1.26 (p < 0.001), 5.91 ± 2.48 versus 1.92 ± 0.99 (p < 0.001) and 7.24 ± 3.20 versus 2.76 ± 1.26 (p < 0.001), respectively. Apo A-1 was correlated to Lp (a) (r = 0.291, p = 0.005). Corticoid dose was not associated to dyslipidaemia, but in multiple regression models, corticoid dose may be negatively related to some atherogenic markers, in particular non-HDL-c. Tunisian patients with markedly active RA experience substantially reduced serum HDL-c and increased TC, LDL-c and Lp (a) concentrations as well as increased TC/HDL-c, LDL-c/HDL-c and non-HDL-c/HDL-c ratios.     

HDL particles from type 1 diabetic patients are unable to reverse the inhibitory effect of oxidised LDL on endothelium-dependent vasorelaxation

Aims/hypothesis In healthy individuals, HDL can counteract the inhibition of vasorelaxation induced by oxidised LDL. Several abnormalities such as increased size, glycation and decreased paraoxonase activity have been reported for HDL from type 1 diabetic patients. Thus, we hypothesised that the ability of HDL to protect vessels against impairments of vasorelaxation would be decreased in these patients. Methods We compared the ability of HDL from 18 type 1 diabetic patients and 12 control participants to counteract the inhibition of endothelium-dependent relaxation induced by oxidised LDL on rabbit aorta rings. Results Serum triacylglycerol and total cholesterol, LDL- and HDL-cholesterol were similar in type 1 diabetic and control participants. Fasting glycaemia and the HDL-fructosamine level were higher in diabetic patients than in controls (9.06 ± 3.55 vs 5.27 ± 0.23 mmol/l, p < 0.005; and 10.2 ± 3.2 vs 7.7 ± 2.5 μmol/g protein, p < 0.05, respectively). HDL composition, size and paraoxonase activity were similar in both groups. HDL from controls reduced the inhibitory effect of oxidised LDL on maximal relaxation (E _max; 79.3 ± 11.8 vs 66.4 ± 11.7%, p < 0.05), whereas HDL from type 1 diabetic patients had no effect (E _max = 70.6 ± 17.4 vs 63.9 ± 17.2%, NS). In type 1 diabetic patients, E _max was not correlated with glycaemia or the HDL-fructosamine level. Conclusions/interpretation HDL particles from type 1 diabetic patients do not protect against inhibition of endothelium-dependent vasorelaxation induced by oxidised LDL, in contrast to HDL particles from healthy individuals. This defect cannot be explained by abnormalities in HDL composition, size or paraoxonase activity, and may contribute to the early development of atherosclerotic lesions in type 1 diabetic patients. L. Perségol and M. Foissac contributed equally to this study.     

Effects of peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ agonists on glucose and lipid metabolism in patients with type 2 diabetes mellitus

Aims/hypothesis The aim of the study was to examine the effects of pioglitazone (PIO), a peroxisome proliferator-activated receptor (PPAR)-γ agonist, and fenofibrate (FENO), a PPAR-α agonist, as monotherapy and in combination on glucose and lipid metabolism. Subjects and methods Fifteen type 2 diabetic patients received FENO (n = 8) or PIO (n = 7) for 3 months, followed by the addition of the other agent for 3 months in an open-label study. Subjects received a 4 h hyperinsulinaemic–euglycaemic clamp and a hepatic fat content measurement at 0, 3 and 6 months. Results Following PIO, fasting plasma glucose (FPG) (p < 0.05) and HbA_1c (p < 0.01) decreased, while plasma adiponectin (AD) (5.5 ± 0.9 to 13.8 ± 3.5 μg/ml [SEM], p < 0.03) and the rate of insulin-stimulated total-body glucose disposal (R _d) (23.8 ± 3.8 to 40.5 ± 4.4 μmol kg⁻¹ min⁻¹, p < 0.005) increased. After FENO, FPG, HbA_1c, AD and R _d did not change. PIO reduced fasting NEFA (784 ± 53 to 546 ± 43 μmol/l, p < 0.05), triacylglycerol (2.12 ± 0.28 to 1.61 ± 0.22 mmol/l, p < 0.05) and hepatic fat content (20.4 ± 4.8 to 10.2 ± 2.5%, p < 0.02). Following FENO, fasting NEFA and hepatic fat content did not change, while triacylglycerol decreased (2.20 ± 0.14 to 1.59 ± 0.13 mmol/l, p < 0.01). Addition of FENO to PIO had no effect on R _d, FPG, HbA_1c, NEFA, hepatic fat content or AD, but triacylglycerol decreased (1.61 ± 0.22 to 1.00 ± 0.15 mmol/l, p < 0.05). Addition of PIO to FENO increased R _d (24.9 ± 4.4 to 36.1 ± 2.2 μmol kg⁻¹ min⁻¹, p < 0.005) and AD (4.1 ± 0.8 to 13.1 ± 2.5 μg/ml, p < 0.005) and reduced FPG (p < 0.05), HbA_1c (p < 0.05), NEFA (p < 0.01), hepatic fat content (18.3 ± 3.1 to 13.5 ± 2.1%, p < 0.03) and triacylglycerol (1.59 ± 0.13 to 0.96 ± 0.9 mmol/l, p < 0.01). Muscle adenosine 5′-monophosphate-activated protein kinase (AMPK) activity did not change following FENO; following the addition of PIO, muscle AMPK activity increased significantly (phosphorylated AMPK:total AMPK ratio 1.2 ± 0.2 to 2.2 ± 0.3, p < 0.01). Conclusions/interpretation We conclude that PPAR-α therapy has no effect on NEFA or glucose metabolism and that addition of a PPAR-α agonist to a PPAR-γ agent causes a further decrease in plasma triacylglycerol, but has no effect on NEFA or glucose metabolism.     

Effect of type 2 diabetes mellitus on exercise intolerance and the physiological responses to exercise in peripheral arterial disease

Aims/hypothesis There are conflicting data about the effect of type 2 diabetes mellitus on exercise tolerance in peripheral arterial disease. To elucidate this problem, we compared the tolerance and physiological responses to treadmill and cycle exercise in 31 patients with peripheral arterial disease and intermittent claudication. Materials and methods One group of these patients had type 2 diabetes (n = 12) and its members were matched for sex and age with a group of patients who did not have diabetes (n = 12). Since BMI and body weight were greater in the diabetic group (28.4 ± 3.7 vs 25.2 ± 2.4 kg/m²; 84.0 ± 14.6 vs 73.8 ± 8.0 kg), we also studied a third, ‘heavy’ group of non-diabetic patients with claudication of similar age (n = 7; BMI = 30.9 ± 5.3 kg/m²; body weight = 85.2 ± 8.2 kg). Results Compared with the ‘light’ non-diabetic group, maximum treadmill times were shorter for the diabetic and heavy non-diabetic groups (1,448 vs 845 and 915 s; ANOVA p = 0.01); maximum cycle time also tended to be shorter (ANOVA, p = 0.08) in the diabetic and heavy non-diabetic groups (median = 1,231 vs 730 and 797 s). The majority of physiological responses assessed were not different between the groups, although the time constant of oxygen uptake during submaximal treadmill and cycle exercise was significantly larger (ANOVA p < 0.05) for the diabetic group. Conclusions/interpretation These data demonstrate that exercise tolerance is lower in diabetic than non-diabetic patients with claudication, but that this difference is due to obesity rather than diabetes itself.     

Effect of short-term ACE inhibitor treatment on peripheral insulin sensitivity in obese insulin-resistant subjects

Aims/hypothesis This study was designed to investigate the effect of short-term ACE inhibitor treatment on insulin sensitivity and to examine possible underlying metabolic and haemodynamic effects in obese insulin-resistant subjects.Methods A randomised, double-blind placebo-controlled trial was performed in 18 obese insulin-resistant men (age, 53 ± 2 years; BMI, 32.6 ± 0.8 kg/m²; homeostasis model assessment of insulin resistance, 5.6 ± 0.5; systolic blood pressure [SBP], 140.8 ± 3.2; diastolic blood pressure [DBP], 88.8 ± 1.6 mmHg), who were free of any medication. The aim was to examine the effects of 2 weeks of ACE inhibitor treatment (ramipril, 5 mg/day) on insulin sensitivity, forearm blood flow, substrate fluxes across the forearm, whole-body substrate oxidation and intramuscular triacylglycerol (IMTG) content.Results Ramipril treatment decreased ACE activity compared with placebo (−22.0 ± 1.7 vs 0.2 ± 1.1 U/l, respectively, p < 0.001), resulting in a significantly reduced blood pressure (SBP, −10.8 ± 2.1 vs −2.7 ± 2.0 mmHg, respectively, p = 0.01; DBP, −10.1 ± 1.3 vs −4.2 ± 2.1 mmHg, respectively, p = 0.03). Ramipril treatment had no effect on whole-body insulin-mediated glucose disposal (before: 17.9 ± 2.0, after: 19.1 ± 2.4 μmol kg body weight⁻¹ min⁻¹, p = 0.44), insulin-mediated glucose uptake across the forearm (before: 1.82 ± 0.39, after: 1.92 ± 0.29 μmol 100 ml forearm tissue⁻¹ min⁻¹, p = 0.81) and IMTG content (before: 45.4 ± 18.8, after: 48.8 ± 27.5 μmol/mg dry muscle, p = 0.92). Furthermore, the increase in carbohydrate oxidation (p < 0.001) and forearm blood flow (p < 0.01), and the decrease in fat oxidation (p < 0.001) during insulin stimulation were not significantly different between treatments.Conclusions/interpretation Short-term ramipril treatment adequately reduced ACE activity and blood pressure, but had no significant effects on insulin sensitivity, forearm blood flow, substrate fluxes across the forearm, whole-body substrate oxidation and IMTG content in obese insulin-resistant subjects.     

Impaired in vivo mitochondrial function but similar intramyocellular lipid content in patients with type 2 diabetes mellitus and BMI-matched control subjects

Aims/hypothesis Mitochondrial dysfunction and increased intramyocellular lipid (IMCL) content have both been implicated in the development of insulin resistance and type 2 diabetes mellitus, but the relative contributions of these two factors in the aetiology of diabetes are unknown. As obesity is an independent determinant of IMCL content, we examined mitochondrial function and IMCL content in overweight type 2 diabetes patients and BMI-matched normoglycaemic controls. Methods In 12 overweight type 2 diabetes patients and nine controls with similar BMI (29.4 ± 1 and 29.3 ± 0.9 kg/m² respectively) in vivo mitochondrial function was determined by measuring phosphocreatine recovery half-time (PCr half-time) immediately after exercise, using phosphorus-31 magnetic resonance spectroscopy. IMCL content was determined by proton magnetic resonance spectroscopic imaging and insulin sensitivity was measured with a hyperinsulinaemic–euglycaemic clamp. Results The PCr half-time was 45% longer in diabetic patients compared with controls (27.3 ± 3.5 vs 18.7 ± 0.9 s, p < 0.05), whereas IMCL content was similar (1.37 ± 0.30 vs 1.25 ± 0.22% of the water resonance), and insulin sensitivity was reduced in type 2 diabetes patients (26.0 ± 2.2 vs 18.9 ± 2.3 μmol min⁻¹ kg⁻¹, p < 0.05 [all mean ± SEM]). PCr half-time correlated positively with fasting plasma glucose (r ² = 0.42, p < 0.01) and HbA_1c (r ² = 0.48, p < 0.05) in diabetic patients. Conclusions/interpretation The finding that in vivo mitochondrial function is decreased in type 2 diabetes patients compared with controls whereas IMCL content is similar suggests that low mitochondrial function is more strongly associated with insulin resistance and type 2 diabetes than a high IMCL content per se. Whether low mitochondrial function is a cause or consequence of the disease remains to be investigated.     

Relationship between glyco-oxidation, antioxidant status and microalbuminuria in type 2 diabetic patients

Aims/hypothesis  This study examined the relationship, if any, between glucose-induced oxidative stress, antioxidant status and microalbuminuria in patients with type 2 diabetes. Methods  The study involved 99 consecutive type 2 diabetic patients (57 men, 42 women). Patients with persistent microalbuminuria were identified and the following variables evaluated: fasting plasma glucose, HbA_1c, malonyldialdehyde (MDA), pentosidine, AGE, the total radical-trapping antioxidant parameter (TRAP), vitamin E, creatinine, estimated GFR and lipid profile. Results  Patients were divided into two groups, i.e. 37 individuals without microalbuminuria (AER <20 μg/min) and 62 with microalbuminuria (AER ≥20 μg/min). The following variables were significantly higher in patients with microalbuminuria than in those without microalbuminuria (mean ± SD): fasting plasma glucose 9.41 ± 2.88 vs 8.19 ± 1.93 mmol/l, p < 0.05; HbA_1c 7.97 ± 1.51 vs 7.39 ± 1.03%, p < 0.05; MDA 1.18 ± 0.35 vs 1.02 ± 0.29 μmol/l, p < 0.05; pentosidine 98.5 ± 24.6 vs 82.9 ± 20.9 pmol/ml, p < 0.005; and AGE 13.2 ± 4.8 vs 10.6 ± 3.8 μg/mg protein, p < 0.01. However, vitamin E and TRAP did not differ between the two groups. Serum creatinine values and estimated GFR were similar in the two groups. Only in patients with microalbuminuria were significant linear correlations seen between AER and both oxidation (HbA_1c r = 0.33, p < 0.01; MDA r = 0.59, p < 0.001; pentosidine r = 0.48, p < 0.001; and AGE r = 0.44, p < 0.001) and antioxidation variables (vitamin E r = −0.55, p < 0.001; TRAP r = −0.49, p < 0.001). Considering all variables together, multiple regression revealed a correlation between microalbuminuria and vitamin E, TRAP, HbA_1c and MDA, but not pentosidine or AGE. Conclusions/interpretation  Our data suggest that microalbuminuria in type 2 diabetic patients might be promoted by an insufficient counter-regulation of the antioxidant system in the event of increased glyco-oxidation/glycation.     

Improved glucose tolerance in mice receiving intraperitoneal transplantation of normal fat tissue

Aims/hypothesis The association between increased (visceral) fat mass, insulin resistance and type 2 diabetes mellitus is well known. Yet, it is unclear whether the mere increase in intra-abdominal fat mass, or rather functional alterations in fat tissue in obesity contribute to the development of insulin resistance in obese patients. Here we attempted to isolate the metabolic effect of increased fat mass by fat tissue transplantation. Methods Epididymal fat pads were removed from male C57Bl6/J mice and transplanted intraperitoneally into male littermates (recipients), increasing the combined perigonadal fat mass by 50% (p < 0.005). At 4 and 8 weeks post-transplantation, glucose and insulin tolerance tests were performed, and insulin, NEFA and adipokines measured. Results Circulating levels of NEFA, adiponectin and leptin were not significantly different between transplanted and sham-operated control mice, while results of the postprandial insulin tolerance test were similar between the two groups. In contrast, under fasting conditions, the mere increase in intra-abdominal fat mass resulted in decreased plasma glucose levels (6.9 ± 0.4 vs 8.1 ± 0.3 mmol/l, p = 0.03) and a ∼20% lower AUC in the glucose tolerance test (p = 0.02) in transplanted mice. Homeostasis model assessment of insulin resistance (HOMA-IR) was 4.1 ± 0.4 in transplanted mice (vs 6.2 ± 0.7 in sham-operated controls) (p = 0.02), suggesting improved insulin sensitivity. Linear regression modelling revealed that while total body weight positively correlated, as expected, with HOMA-IR (β: 0.728, p = 0.006), higher transplanted fat mass correlated with lower HOMA-IR (β: −0.505, p = 0.031). Conclusions/interpretation Increasing intra-abdominal fat mass by transplantation of fat from normal mice improved, rather than impaired, fasting glucose tolerance and insulin sensitivity, achieving an effect opposite to the expected metabolic consequence of increased visceral fat in obesity.     

The effect of moderate exercise on postprandial glucose homeostasis in NIDDM patients

Summary The influence of exercise on glycaemia in the post-prandial state was studied for the first time in non-insulin-dependent diabetic (NIDDM) patients. Meal-induced glucose responses were followed for 8 h in 9 diet-treated patients with NIDDM. Subjects consumed a standardized breakfast and 4 h later a standardized lunch. They were studied in the resting state (control day (CD)) and on another day 45 min of bicycle exercise (53 ± 2 % V˙_{O 2} ^max (mean ± SEM)) was performed 45 min after breakfast (exercise day (ED)). On day 3 (diet day (DD)), the breakfast meal was reduced corresponding to the extra energy expenditure during the exercise period on ED. Responses were calculated as areas under the plasma concentration curve (AUC) during 4 h after either breakfast (B-AUC) or lunch (L-AUC). B-AUC for glucose was identical on ED (215 ± 63 mmol/l · 240 min) and DD (219 ± 60 mmol/l · 240 min) and on these days lower (p < 0.05) than on CD (453 ± 78 mmol/l · 240 min). L-AUC for glucose on CD, ED and DD did not differ significantly. B-AUCs for both insulin and C-peptide were also significantly lower on ED and DD as compared to CD (Insulin: 31337 ± 8682, 26092 ± 6457 and 47649 ± 15046 mmol/l · 240 min, respectively. C-peptide: 99 ± 19, 104 ± 26 and 195 ± 31 pmol/ml · 240 min, respectively). Rate of appearance (Ra) for glucose was unaffected by exercise whereas rate of disappearance (Rd) increased significantly. No differences in Ra or Rd were observed after lunch. In conclusion, postprandial exercise of moderate intensity decreases glycaemia and plasma insulin levels after breakfast in NIDDM patients, but this effect does not persist during and after the following lunch meal. Reduction of breakfast caloric intake has the same effect on postprandial glycaemia and insulin secretion as an equivalent exercise-induced increase in caloric expenditure. [Diabetologia (1997) 40: 447–453] Received: 4 October 1996 and in revised form: 18 December 1996     

Variations in the four and a half LIM domains 1 gene (<Emphasis Type="Italic">FHL1</Emphasis>) are associated with fasting insulin and insulin sensitivity responses to regular exercise

Aims/hypothesis The expression of the four and a half LIM domains 1 gene (FHL1) is increased in the muscle of individuals who show an improvement in insulin sensitivity index (S _I) after 20 weeks of exercise training. The aim of the present study was to investigate associations between three FHL1 single nucleotide polymorphisms (SNPs) and variables derived from an IVGTT, both in the sedentary state and in response to exercise training, in participants in the HERITAGE Family Study. Materials and methods SNPs were typed using fluorescence polarisation methodology. Analyses were performed separately by sex and in black and white individuals. Results In black participants, no associations were found with any of the SNPs. In white women (n = 207), SNP rs9018 was associated with the disposition index (D _I), which is calculated as S _I generated from the MINMOD program (×10⁻⁴ min⁻¹[μU/ml]⁻¹) multiplied by acute insulin response to glucose (AIR_g; pmol/l × 10 min), and the glucose disappearance index (K _g) training responses (p = 0.016 and p = 0.008, respectively). In white men (n = 222), all SNPs were associated with fasting glucose levels (p ≤ 0.05) and SNP rs2180062 with the insulin sensitivity index (S _I) (p = 0.04) in the sedentary state. Two SNPs were associated with fasting insulin training response. Fasting insulin decreased to a greater extent in carriers of the rs2180062 C allele (p = 0.01) and rs9018 T allele (p = 0.04). With exercise training, S _I (×10⁻⁴ min⁻¹[μU/ml]⁻¹: 0.68 ± 0.20 vs −0.77 ± 0.44, p = 0.046), D _I (319 ± 123 vs –528 ± 260, p = 0.006) and K _g (per 100 min: 0.09 ± 0.04 vs −0.14 ± 0.8, p = 0.03) improved more in the C allele carriers at rs2180062 than in the T allele carriers. Conclusions/interpretation Fasting insulin and S _I responses to exercise training were associated with DNA sequence variation in FHL1 in white men. Whether these associations exist only in white men remains to be investigated. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.