Attendance in a national screening program for diabetic retinopathy: a population-based study of 205,970 patients.

AIMS: A nationwide diabetic retinopathy (DR) screening program has been established in Denmark since 2013. We aimed to perform an evaluation of adherence to DR screenings and to examine whether non-adherence was correlated to DR progression. METHODS: The population consisted of a register-based cohort, who participated in the screening program from 2013 to 2018. We analyzed age, gender, marital status, DR level (International Clinical DR severity scale, none, mild-, moderate-, severe non-proliferative DR (NPDR) and proliferative DR (PDR)), comorbidities and socioeconomic factors. The attendance pattern of patients was grouped as either timely (no delays > 33%), delayed (delays > 33%) or one-time attendance (unexplained). RESULTS: We included 205,970 patients with 591,136 screenings. Rates of timely, delayed and one-time attendance were 53.0%, 35.5% and 11.5%, respectively. DR level at baseline was associated with delays (mild-, moderate-, severe NPDR and PDR) and one-time attendance (moderate-, severe NPDR and PDR) with relative risk ratios (RRR) of 1.68, 2.27, 3.14, 2.44 and 1.18, 2.07, 1.26, respectively (P < 0.05). Delays at previous screenings were associated with progression to severe NPDR or PDR (hazard ratio (HR) 2.27, 6.25 and 12.84 for 1, 2 and 3+ delays, respectively). Any given delay doubled the risk of progression (HR 2.28). CONCLUSIONS: In a national cohort of 205,970 patients, almost half of the patients attended DR screening later than scheduled or dropped out after first screening episode. This was, in particular, true for patients with any levels of DR at baseline. DR progression in patients with delayed attendance, increased with the number of missed appointments.

Mitochondria, glycogen, and lipid droplets in skeletal muscle during testosterone treatment and strength training: a randomized, double-blinded, placebo-controlled trial.

Low testosterone levels in aging men are associated with insulin resistance. Mitochondrial dysfunction, changes in glycogen metabolism, and lipid accumulation are linked to insulin resistance in skeletal muscle. In this randomized, double-blinded, placebo-controlled study, we investigated the effects of six-month testosterone replacement therapy (TRT) and strength training (ST) on mitochondrial, glycogen, and lipid droplet (LD) content in skeletal muscle of aging men with subnormal bioavailable testosterone (BioT) levels. Mitochondrial, glycogen, and LD volume fractions in muscle biopsies were estimated by transmission electron microscopy. Insulin sensitivity (insulin-stimulated Rd) and body composition were assessed by euglycemic-hyperinsulinemic clamp and dual X-ray absorptiometry, respectively. TRT significantly increased total testosterone levels, BioT, and lean body mass (LBM) (p < 0.05), whereas percent body fat decreased (p < 0.05), and insulin sensitivity was unchanged. Baseline mitochondrial volume fraction correlated inversely with percent body fat (ρ = -0.43; p = 0.003). Δ-mitochondrial fraction correlated positively with Δ-total testosterone (ρ = 0.70; p = 0.02), and Δ-glycogen fraction correlated inversely with Δ-LBM (ρ = -0.83; p = 0.002) during six-month TRT, but no significant changes were observed in mitochondrial, glycogen, and LD volume fractions during TRT and ST. In conclusion, in this exploratory small-scale study, the beneficial effects of six-month TRT on total testosterone, LBM, and percent body fat were not followed by significant changes in fractions of mitochondria, glycogen, or lipid in skeletal muscle of aging men with lowered testosterone levels. Six-month ST or combined three-month ST+TRT did not change intramyocellular mitochondria, glycogen, and LD fractions compared to placebo. However, further studies with a larger sample size are needed.

MR spectroscopy of hepatic fat and adiponectin and leptin levels during testosterone therapy in type 2 diabetes: a randomized, double-blinded, placebo-controlled trial.

BACKGROUND: Men with type 2 diabetes mellitus (T2D) often have lowered testosterone levels and an increased risk of cardiovascular disease (CVD). Ectopic fat increases the risk of CVD, whereas subcutaneous gluteofemoral fat protects against CVD and has a beneficial adipokine-secreting profile. HYPOTHESIS: Testosterone replacement therapy (TRT) may reduce the content of ectopic fat and improve the adipokine profile in men with T2D. DESIGN AND METHODS: A randomized, double-blinded, placebo-controlled study in 39 men aged 50-70 years with T2D and bioavailable testosterone levels <7.3 nmol/L. Patients were randomized to TRT (n = 20) or placebo gel (n = 19) for 24 weeks. Thigh subcutaneous fat area (TFA, %fat of total thigh volume), subcutaneous abdominal adipose tissue (SAT, % fat of total abdominal volume) and visceral adipose tissue (VAT, % fat of total abdominal volume) were measured by magnetic resonance (MR) imaging. Hepatic fat content was estimated by single-voxel MR spectroscopy. Adiponectin and leptin levels were measured by in-house immunofluorometric assay. Coefficients (b) represent the placebo-controlled mean effect of intervention. RESULTS: TFA (b = -3.3 percentage points (pp), P = 0.009), SAT (b = -3.0 pp, P = 0.006), levels of adiponectin (b = -0.4 mg/L, P = 0.045), leptin (b = -4.3 µg/mL, P < 0.001), leptin:adiponectin ratio (b = -0.53, P = 0.001) and HDL cholesterol (b = -0.11 mmol/L, P = 0.009) decreased during TRT compared with placebo. Hepatic fat content and VAT were unchanged. CONCLUSIONS: The effects of TRT on cardiovascular risk markers were ambiguous. We observed potentially harmful changes in cardiovascular risk parameters, markedly reduced subcutaneous fat and unchanged ectopic fat during TRT and a reduction in adiponectin levels. On the other hand, the decrease in leptin and leptin:adiponectin ratio assessments could reflect an amelioration of the cardiovascular risk profile linked to hyperleptinaemia in ageing men with T2D.

Initiation of glucose-lowering treatment decreases international normalized ratio levels among users of vitamin K antagonists: a self-controlled register study.

UNLABELLED: ESSENTIALS: It is not known if initiation of glucose-lowering drugs alters the efficacy of vitamin K antagonists (VKA). We examined if glucose-lowering drugs affected international normalized ratio (INR) in VKA-treated patients. Upon initiating glucose-lowering drugs, 51% of patients had INR values below the therapeutic window. Monitoring of INR levels should be intensified upon initiation of glucose-lowering drugs. BACKGROUND: It is not known whether initiation of antidiabetic treatment affects the effect of vitamin K antagonists (VKAs). It was previously shown that metformin affects the effect of one VKA, phenprocoumon. OBJECTIVES: The aim of this study was to determine if initiation of glucose-lowering treatment affects the international normalized ratio (INR) and dose requirements of the anticoagulant VKAs warfarin and phenprocoumon. PATIENTS/METHODS: We performed a self-controlled retrospective register-based study. A total of 118 patients commencing glucose-lowering treatment while being treated with warfarin or phenprocoumon were included in the study. We compared INR, dose/INR and proportion of patients with at least one sub-therapeutic INR measurement before and after initiation of glucose-lowering treatment. RESULTS: Initiation of glucose-lowering treatment caused mean INR to decrease from 2.5 to 2.2 (decrease of -0.3 [95% CI: -0.1; -0.5]) and led to more than half of the patients having at least one sub-therapeutic INR measurement. Six to 12 weeks later, the VKA dose/INR was increased by 11%, indicating a weakened effect of the VKA. CONCLUSION: Initiation of glucose-lowering treatment reduces the anticoagulant effect of VKAs to an extent that is likely to be clinically relevant. This finding needs confirmation and mechanistic explanation.

Changes in HbA1c and circulating and adipose tissue androgen levels in overweight-obese women with polycystic ovary syndrome in response to electroacupuncture.

AIM: Insulin sensitivity is ~40% lower in women with polycystic ovary syndrome (PCOS) than in controls. We tested the hypothesis that 5 weeks of electroacupuncture treatment improves glucose regulation and androgen levels in overweight/obese women with PCOS. MATERIAL AND METHODS: Seventeen women with PCOS, aged 18 to 38 years, with a body mass index (BMI) ≥25 kg/m2 and diagnosed with PCOS were included in this experimental and feasibility study and subjected to five weeks of electroacupuncture treatments three times/week. The primary outcome was changes in whole-body glucose homeostasis measured by euglycemic hyperinsulinemic clamp before and after the intervention. Secondary outcome were changes in HbA1c, circulating catecholamines, adipocyte size and adipose tissue expression of sex steroids and nerve growth factor (NGF). RESULTS: No significant change in glucose homeostasis was observed, but HbA1c decreased by 9.5% (p = 0.004), circulating testosterone decreased by 22% (p = 0.0007) and dihydrotestosterone decreased by 12% (p = 0.007). The two vagal activity markers of plasma serotonin levels and the dopamine metabolite homovanillic acid decreased by 21% (p = 0.027) and 20% (p = 0.011), respectively. Adipose tissue concentrations of testosterone decreased by 18% (p = 0.049), and androstenedione decreased by 13% (p = 0.035), and mature NGF/proNGF ratio, a marker of sympathetic activity, increased (p = 0.04). These changes occurred without changes in anthropometrics. CONCLUSION: Five weeks of electroacupuncture treatment improves HbA1c and circulating and adipose tissue androgens in women with PCOS. This effect is mediated, at least in part, via modulation of vagal activity and adipose tissue sympathetic activity. Based on these findings, we have recently initiated a randomized controlled study (NTC02647827).

Obesity and carotid artery remodeling.

BACKGROUND/OBJECTIVE: The present study tested the hypothesis that obesity-related changes in carotid intima-media thickness (IMT) might represent not only preclinical atherosclerosis but an adaptive remodeling meant to preserve circumferential wall stress (CWS) in altered hemodynamic conditions characterized by body size-dependent increase in stroke volume (SV) and blood pressure (BP). SUBJECTS/METHODS: Common carotid artery (CCA) luminal diameter (LD), IMT and CWS were measured in three different populations in order to study: (A) cross-sectional associations between SV, BP, anthropometric parameters and CCA LD (266 healthy subjects with wide range of body weight (24-159 kg)); (B) longitudinal associations between CCA LD and 3-year IMT progression rate (ΔIMT; 571 healthy non-obese subjects without increased cardiovascular (CV) risk); (C) the impact of obesity on CCA geometry and CWS (88 obese subjects without CV complications and 88 non-obese subjects matched for gender and age). RESULTS: CCA LD was independently associated with SV that was determined by body size. In the longitudinal study, baseline LD was an independent determinant of ΔIMT, and ΔIMT of subjects in the highest LD quartile was significantly higher (28±3 µm) as compared with those in the lower quartiles (8±3, 16±4 and 16±3 µm, P=0.001, P<0.05 and P=0.01, respectively). In addition, CCA CWS decreased during the observational period in the highest LD quartile (from 54.2±8.6 to 51.6±7.4 kPa, P<0.0001). As compared with gender- and age-matched lean individuals, obese subjects had highly increased CCA LD and BP (P<0.0001 for both), but only slightly higher CWS (P=0.05) due to a significant increase in IMT (P=0.005 after adjustment for confounders). CONCLUSIONS: Our findings suggest that in obese subjects, the CCA wall thickens to compensate the luminal enlargement caused by body size-induced increase in SV, and therefore, to normalize the wall stress. CCA diameter in obesity could represent an additional biomarker, depicting the impact of altered hemodynamics on arterial wall.

Glutamic acid decarboxylase autoantibody-positivity post-partum is associated with impaired ß-cell function in women with gestational diabetes mellitus.

AIMS: To investigate whether the presence of glutamic acid decarboxylase (GAD) autoantibodies post-partum in women with prior gestational diabetes mellitus was associated with changes in metabolic characteristics, including ß-cell function and insulin sensitivity. METHODS: During 1997-2010, 407 women with gestational diabetes mellitus were offered a 3-month post-partum follow-up including anthropometrics, serum lipid profile, HbA1c and GAD autoantibodies, as well as a 2-h oral glucose tolerance test (OGTT) with blood glucose, serum insulin and C-peptide at 0, 30 and 120 min. Indices of insulin sensitivity and insulin secretion were estimated to assess insulin secretion adjusted for insulin sensitivity, disposition index (DI). RESULTS: Twenty-two (5.4%) women were positive for GAD autoantibodies (GAD+ve) and the remainder (94.6%) were negative for GAD autoantibodies (GAD-ve). The two groups had similar age and prevalence of diabetes mellitus. Women who were GAD+ve had significantly higher 2-h OGTT glucose concentrations during their index-pregnancy (10.5 vs. 9.8 mmol/l, P = 0.001), higher fasting glucose (5.2 vs. 5.0 mmol/l, P = 0.02) and higher 2-h glucose (7.8 vs. 7.1 mmol/l, P = 0.05) post-partum. Fasting levels of C-peptide and insulin were lower in GAD+ve women compared with GAD-ve women (520 vs. 761 pmol/l, P = 0.02 and 33 vs. 53 pmol/l, P = 0.05) Indices of insulin sensitivity were similar in GAD+ve and GAD-ve women, whereas all estimates of DI were significantly reduced in GAD+ve women. CONCLUSION: GAD+ve women had higher glucose levels and impaired insulin secretion adjusted for insulin sensitivity (DI) compared with GAD-ve women. The combination of OGTT and GAD autoantibodies post-partum identify women with impaired ß-cell function. These women should be followed with special focus on development of Type 1 diabetes.

Impact of objectively measured sedentary behaviour on changes in insulin resistance and secretion over 3 years in the RISC study: interaction with weight gain.

AIMS: The importance of reducing sedentary time is increasingly being recognized in the prevention of diabetes and cardiovascular disease. Despite this, the prospective association between sedentary time and physical activity with insulin sensitivity and cardiometabolic risk factors has been little studied. METHODS: In an analysis of data from the European RISC study, sedentary time and time spent in activity of moderate or vigorous intensity were assessed by accelerometry at baseline in 313 men and 414 women, aged 30-60 years, with insulin sensitivity as measured by euglycaemic-hyperinsulinaemic clamp. Three years later, cardiometabolic risk factors (anthropometry, glucose, insulin, lipids) were available for 549 participants. RESULTS: In cross-sectional analyses using baseline data, after adjusting for age, gender, recruitment centre and time spent in activity of moderate or vigorous intensity, significant unfavourable associations were observed between higher sedentary time with body weight, HDL cholesterol, triglycerides, clamp-measured insulin sensitivity and insulin secretion (all P(trend)<0.002). Sedentary time remained significantly associated with insulin secretion after adjusting for insulin sensitivity (P(trend)=0.02). In longitudinal analyses, higher baseline sedentary time was associated with 3-year increases in fasting glucose, fasting insulin and the HOMA insulin-resistance index score for the 50% of the study population who increased their BMI by at least 0.3 kg/m(2) (all P(trend)<0.01); these relationships remained significant after adjusting for time spent in activity of moderate or vigorous intensity. The 3-year increase in insulin secretion was lower in those spending more time doing activity of moderate or vigorous intensity (P(trend)=0.03). CONCLUSION: These prospective data suggest that less sedentary behaviour may partly counteract some of the negative effects of increasing body weight on glucose-insulin homoeostasis.

Osteoprotegerin levels decrease during testosterone therapy in aging men and are associated with changed distribution of regional fat.

The cardiovascular effects of testosterone treatment are debated. Osteoprotegerin (OPG) is an independent marker of cardiovascular risk. We investigated the effect of testosterone therapy on OPG levels in aging men with low normal bioavailable testosterone levels. A randomized, double-blinded, placebo-controlled study of 6 months testosterone therapy (gel) in 38 men aged 60-78 years with bioavailable testosterone <7.3 nmol/l and waist circumference >94 cm was performed. Clinical evaluation, OPG, and C-reactive protein (CRP) measurements were carried out. Lean body mass (LBM), total fat mass, and bone mineral density (BMD) were established by dual X-ray absorptiometry. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were measured by magnetic resonance imaging. Power calculation was based on an increase in LBM during testosterone therapy and responders were defined as testosterone treated patients with increased LBM (Δ LBM positive), n=14. Data are presented as median (interquartile range). Testosterone therapy decreased total fat mass and SAT, whereas VAT was unchanged (n=38). OPG levels decreased during testosterone therapy (from 2.0 (1.9-2.5) to 1.9 (1.6-2.2) ng/ml, p<0.05 vs. placebo), whereas CRP levels were unchanged (n=38). In responders to testosterone therapy (n=14), ΔOPG levels were inversely associated with ΔSAT (r= - 0.60, p=0.03) and positively associated with ΔVAT (r=0.56, p=0.04). OPG levels decreased during testosterone therapy suggesting decreased cardiovascular risk. Decreased OPG levels were associated with changes in regional fat distribution and future studies are needed to further evaluate the association between OPG and regional fat mass distribution.

Depressive symptoms, insulin sensitivity and insulin secretion in the RISC cohort study.

AIM: This study explored the association of depressive symptoms with indices of insulin sensitivity and insulin secretion in a cohort of non-diabetic men and women aged 30 to 64 years. METHODS: The study population was derived from the 3-year follow-up of the Relationship between Insulin Sensitivity and Cardiovascular Disease Risk (RISC) study. Presence of significant depressive symptoms was defined as a Center for Epidemiologic Studies Depression Scale (CES-D) score ≥ 16. Standard oral glucose tolerance tests were performed. Insulin sensitivity was assessed with the oral glucose insulin sensitivity (OGIS) index. Insulin secretion was estimated using three model-based parameters of insulin secretion (beta-cell glucose sensitivity, the potentiation factor ratio, and beta-cell rate sensitivity). RESULTS: A total of 162 out of 1027 participants (16%) had significant depressive symptoms. Having significant depressive symptoms was not related to either OGIS [standardized beta (ß) -0.033; P=0.24] or beta-cell glucose sensitivity (ß -0.007; P=0.82). Significant depressive symptoms were related to decreased beta-cell rate sensitivity (odds ratio for significant depressive symptoms of the lowest vs. highest quartile of beta-cell rate sensitivity was 2.04; P=0.01). Also, significant depressive symptoms were associated with a statistically significant decrease in the potentiation factor ratio in unadjusted models, but not in the fully adjusted model. CONCLUSION: Depressive symptoms were not related to insulin sensitivity and tended to be weakly associated to some parameters of insulin secretion in non-diabetic individuals. Prospective studies are needed to study the temporal association between depression and insulin secretion.

Moderate alcohol consumption is associated with improved insulin sensitivity, reduced basal insulin secretion rate and lower fasting glucagon concentration in healthy women.

AIMS/HYPOTHESIS: Moderate alcohol consumption is associated with a reduced risk of type 2 diabetes with a stronger effect in women. As the underlying mechanisms remain poorly characterised, we investigated its relationship with insulin resistance, insulin secretion, clearance of insulin and glucagon concentration. METHODS: One-thousand two-hundred and seventy-six non-diabetic individuals from the RISC (relationship between insulin sensitivity and cardiovascular disease) study without high alcohol consumption were studied; all had a euglycaemic-hyperinsulinaemic clamp and an OGTT with assessment of insulin sensitivity, secretion and clearance. RESULTS: Alcohol consumption was positively associated with insulin sensitivity in women (ß = 0.15, p ( trend ) = 0.005) and in men (ß = 0.07, p ( trend ) = 0.07) after controlling for age, centre, waist, smoking and physical activity. In women, this association persisted after adjustment for adiponectin but was attenuated after controlling for HDL-cholesterol, suggesting that part of the protection is related to a higher HDL-cholesterol concentration. Higher alcohol consumption was associated with lower basal insulin secretion in women only (ß = -0.10, p ( trend ) = 0.004) and this association persisted after adjustment for insulin sensitivity. In men, increasing alcohol consumption was associated with enhanced insulin clearance and increased fasting NEFA concentrations, independently of insulin sensitivity. Fasting glucagon decreased with increasing alcohol in women only (abstainers 9.2 ± 4.4; <28 g/week 8.6 ± 4.0; 28-64 g/week 8.1 ± 3.7; >64 g/week 7.5 ± 3.1 pmol/l; p ( trend ) = 0.01). CONCLUSIONS/INTERPRETATION: Light-to-moderate alcohol consumption was associated in healthy women with enhanced insulin sensitivity, reduced basal insulin secretion rate and lower fasting plasma glucagon concentration, providing consistent mechanisms for the reduced risk of diabetes.

Adult glucose metabolism in extremely birthweight-discordant monozygotic twins.

AIMS/HYPOTHESIS: Low birthweight (BW) is associated with increased risk of type 2 diabetes. We compared glucose metabolism in adult BW-discordant monozygotic (MZ) twins, thereby controlling for genetic factors and rearing environment. METHODS: Among 77,885 twins in the Danish Twin Registry, 155 of the most BW-discordant MZ twin pairs (median BW difference 0.5 kg) were assessed using a 2 h oral glucose tolerance test with sampling of plasma (p-)glucose, insulin, C-peptide, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1. HOMA for beta cell function (HOMA-ß) and insulin resistance (HOMA-IR), and also insulin sensitivity index (BIGTT-SI) and acute insulin response (BIGTT-AIR), were calculated. Subgroup analyses were performed in those with: (1) double verification of BW difference; (2) difference in BW >0.5 kg; and (3) no overt metabolic disease (type 2 diabetes, hyperlipidaemia or thyroid disease). RESULTS: No intra-pair differences in p-glucose, insulin, C-peptide, incretin hormones, HOMA-ß, HOMA-IR or BIGTT-SI were identified. p-Glucose at 120 min was higher in the twins with the highest BW without metabolic disease, and BIGTT-AIR was higher in those with the highest BW although not in pairs with a BW difference of >0.5 kg. CONCLUSIONS/INTERPRETATION: BW-discordant MZ twins provide no evidence for a detrimental effect of low BW on glucose metabolism in adulthood once genetic factors and rearing environment are controlled for.

Hyperglycaemia normalises insulin action on glucose metabolism but not the impaired activation of AKT and glycogen synthase in the skeletal muscle of patients with type 2 diabetes.

AIMS/HYPOTHESIS: In type 2 diabetes, reduced insulin-stimulated glucose disposal, primarily glycogen synthesis, is associated with defective insulin activation of glycogen synthase (GS) in skeletal muscle. Hyperglycaemia may compensate for these defects, but to what extent it involves improved insulin signalling to glycogen synthesis remains to be clarified. METHODS: Whole-body glucose metabolism was studied in 12 patients with type 2 diabetes, and 10 lean and 10 obese non-diabetic controls by means of indirect calorimetry and tracers during a euglycaemic-hyperinsulinaemic clamp. The diabetic patients underwent a second isoglycaemic-hyperinsulinaemic clamp maintaining fasting hyperglycaemia. Muscle biopsies from m. vastus lateralis were obtained before and after the clamp for examination of GS and relevant insulin signalling components. RESULTS: During euglycaemia, insulin-stimulated glucose disposal, glucose oxidation and non-oxidative glucose metabolism were reduced in the diabetic group compared with both control groups (p < 0.05). This was associated with impaired insulin-stimulated GS and AKT2 activity, deficient dephosphorylation at GS sites 2 + 2a, and reduced Thr308 and Ser473 phosphorylation of AKT. When studied under hyperglycaemia, all variables of insulin-stimulated glucose metabolism were normalised compared with the weight-matched controls. However, insulin activation and dephosphorylation (site 2 + 2a) of GS as well as activation of AKT2 and phosphorylation at Thr308 and Ser473 remained impaired (p < 0.05). CONCLUSIONS/INTERPRETATIONS: These data confirm that hyperglycaemia compensates for decreased whole-body glucose disposal in type 2 diabetes. In contrast to previous less well-controlled studies, we provide evidence that the compensatory effect of hyperglycaemia in patients with type 2 diabetes does not involve normalisation of insulin action on GS or upstream signalling in skeletal muscle.

The proteomic signature of insulin-resistant human skeletal muscle reveals increased glycolytic and decreased mitochondrial enzymes.

AIMS/HYPOTHESIS: The molecular mechanisms underlying insulin resistance in skeletal muscle are incompletely understood. Here, we aimed to obtain a global picture of changes in protein abundance in skeletal muscle in obesity and type 2 diabetes, and those associated with whole-body measures of insulin action. METHODS: Skeletal muscle biopsies were obtained from ten healthy lean (LE), 11 obese non-diabetic (OB), and ten obese type 2 diabetic participants before and after hyperinsulinaemic-euglycaemic clamps. Quantitative proteome analysis was performed by two-dimensional differential-gel electrophoresis and tandem-mass-spectrometry-based protein identification. RESULTS: Forty-four protein spots displayed significant (p < 0.05) changes in abundance by at least a factor of 1.5 between groups. Several proteins were identified in multiple spots, suggesting post-translational modifications. Multiple spots containing glycolytic and fast-muscle proteins showed increased abundance, whereas spots with mitochondrial and slow-muscle proteins were downregulated in the OB and obese type 2 diabetic groups compared with the LE group. No differences in basal levels of myosin heavy chains were observed. The abundance of multiple spots representing glycolytic and fast-muscle proteins correlated negatively with insulin action on glucose disposal, glucose oxidation and lipid oxidation, while several spots with proteins involved in oxidative metabolism and mitochondrial function correlated positively with these whole-body measures of insulin action. CONCLUSIONS/INTERPRETATION: Our data suggest that increased glycolytic and decreased mitochondrial protein abundance together with a shift in muscle properties towards a fast-twitch pattern in the absence of marked changes in fibre-type distribution contribute to insulin resistance in obesity with and without type 2 diabetes. The roles of several differentially expressed or post-translationally modified proteins remain to be elucidated.

Testosterone therapy decreases subcutaneous fat and adiponectin in aging men.

OBJECTIVE: Testosterone therapy increases lean body mass and decreases total fat mass in aging men with low normal testosterone levels. The major challenge is, however, to determine whether the metabolic consequences of testosterone therapy are overall positive. We have previously reported that 6-month testosterone therapy did not improve insulin sensitivity. We investigated the effect of testosterone therapy on regional body fat distribution and on the levels of the insulin-sensitizing adipokine, adiponectin, in aging men with low normal bioavailable testosterone levels. DESIGN: A randomized, double-blinded, placebo-controlled study on 6-month testosterone treatment (gel) in 38 men, aged 60-78 years, with bioavailable testosterone <7.3 nmol/l, and a waist circumference >94 cm. METHODS: Central fat mass (CFM) and lower extremity fat mass (LEFM) were measured by dual X-ray absorptiometry. Subcutaneous abdominal adipose tissue (SAT), visceral adipose tissue (VAT), and thigh subcutaneous fat area (TFA) were measured by magnetic resonance imaging. Adiponectin levels were measured using an in-house immunofluorometric assay. Coefficients (b) represent the placebo-controlled mean effect of intervention. RESULTS: LEFM was decreased (b = -0.47 kg, P = 0.07) while CFM did not change significantly (b = -0.66 kg, P = 0.10) during testosterone therapy. SAT (b = -3.0%, P = 0.018) and TFA (b = -3.0%, P < 0.001) decreased, while VAT (b = 1.0%, P = 0.54) remained unchanged. Adiponectin levels decreased during testosterone therapy (b = -1.3 mg/l, P = 0.001). CONCLUSION: Testosterone therapy decreased subcutaneous fat on the abdomen and lower extremities, but visceral fat was unchanged. Moreover, adiponectin levels were significantly decreased during testosterone therapy.

Common variation in oxidative phosphorylation genes is not a major cause of insulin resistance or type 2 diabetes.

AIMS/HYPOTHESIS: There is substantial evidence that mitochondrial dysfunction is linked to insulin resistance and is present in several tissues relevant to the pathogenesis of type 2 diabetes. Here, we examined whether common variation in genes involved in oxidative phosphorylation (OxPhos) contributes to type 2 diabetes susceptibility or influences diabetes-related metabolic traits. METHODS: OxPhos gene variants (n = 10) that had been nominally associated (p < 0.01) with type 2 diabetes in a recent genome-wide meta-analysis (n = 10,108) were selected for follow-up in 3,599 type 2 diabetic and 4,956 glucose-tolerant Danish individuals. A meta-analysis of these variants was performed in 11,729 type 2 diabetic patients and 43,943 non-diabetic individuals. The impact on OGTT-derived metabolic traits was evaluated in 5,869 treatment-naive individuals from the Danish Inter99 study. RESULTS: The minor alleles of COX10 rs9915302 (p = 0.02) and COX5B rs1466100 (p = 0.005) showed nominal association with type 2 diabetes in our Danish cohort. However, in the meta-analysis, none of the investigated variants showed a robust association with type 2 diabetes after correction for multiple testing. Among the alleles potentially associated with type 2 diabetes, none negatively influenced surrogate markers of insulin sensitivity in non-diabetic participants, while the minor alleles of UQCRC1 rs2228561 and COX10 rs10521253 showed a weak (p < 0.01 to p < 0.05) negative influence on indices of glucose-stimulated insulin secretion. CONCLUSIONS/INTERPRETATION: We cannot rule out the possibility that common variants in or near OxPhos genes may influence beta cell function in non-diabetic individuals. However, our quantitative trait studies and a sufficiently large meta-analysis indicate that common variation in proximity to the examined OxPhos genes is not a major cause of insulin resistance or type 2 diabetes.

Plasma sCD36 is associated with markers of atherosclerosis, insulin resistance and fatty liver in a nondiabetic healthy population.

OBJECTIVES: Insulin resistance is associated with increased CD36 expression in a number of tissues. Moreover, excess macrophage CD36 may initiate atherosclerotic lesions. The aim of this study was to determine whether plasma soluble CD36 (sCD36) was associated with insulin resistance, fatty liver and carotid atherosclerosis in nondiabetic subjects. METHODS: In 1296 healthy subjects without diabetes or hypertension recruited from 19 centres in 14 European countries (RISC study), we determined the levels of sCD36, adiponectin, lipids and liver enzymes, insulin sensitivity (M/I) by euglycaemic-hyperinsulinaemic clamp, carotid atherosclerosis as intima-media thickness (IMT) and two estimates of fatty liver, the fatty liver index (FLI) and liver fat percentage (LF%). RESULTS: IMT, FLI, LF%, presence of the metabolic syndrome, impaired glucose regulation, insulin and triglycerides increased across sCD36 quartiles (Q2-Q4), whereas adiponectin and M/I decreased (P ≤ 0.01). sCD36 was lower in women than in men (P = 0.045). Log sCD36 showed a bimodal distribution, and amongst subjects with sCD36 within the log-normal distribution (log-normal population, n = 1029), sCD36 was increased in subjects with impaired glucose regulation (P = 0.045), metabolic syndrome (P = 0.006) or increased likelihood of fatty liver (P < 0.001). sCD36 correlated significantly with insulin, triglycerides, M/I and FLI (P < 0.05) after adjustment for study centre, gender, age, glucose tolerance status, smoking habits and alcohol consumption. In the log-normal population, these relationships were stronger than in the total study population and, additionally, sCD36 was significantly associated with LF% and IMT (P < 0.05). CONCLUSIONS: In this cross-sectional study of nondiabetic subjects, sCD36 was significantly associated with indices of insulin resistance, carotid atherosclerosis and fatty liver. Prospective studies are needed to further evaluate the role of sCD36 in the inter-relationship between atherosclerosis, fatty liver and insulin resistance.

Impaired insulin-induced site-specific phosphorylation of TBC1 domain family, member 4 (TBC1D4) in skeletal muscle of type 2 diabetes patients is restored by endurance exercise-training.

AIMS/HYPOTHESIS: Insulin-mediated glucose disposal rates (R(d)) are reduced in type 2 diabetic patients, a process in which intrinsic signalling defects are thought to be involved. Phosphorylation of TBC1 domain family, member 4 (TBC1D4) is at present the most distal insulin receptor signalling event linked to glucose transport. In this study, we examined insulin action on site-specific phosphorylation of TBC1D4 and the effect of exercise training on insulin action and signalling to TBC1D4 in skeletal muscle from type 2 diabetic patients. METHODS: During a 3 h euglycaemic-hyperinsulinaemic (80 mU min⁻¹ m⁻²) clamp, we obtained M. vastus lateralis biopsies from 13 obese type 2 diabetic and 13 obese, non-diabetic control individuals before and after 10 weeks of endurance exercise-training. RESULTS: Before training, reductions in insulin-stimulated R (d), together with impaired insulin-stimulated glycogen synthase fractional velocity, Akt Thr³°8 phosphorylation and phosphorylation of TBC1D4 at Ser³¹8, Ser588 and Ser75¹ were observed in skeletal muscle from diabetic patients. Interestingly, exercise-training normalised insulin-induced TBC1D4 phosphorylation in diabetic patients. This happened independently of increased TBC1D4 protein content, but exercise-training did not normalise Akt phosphorylation in diabetic patients. In both groups, training-induced improvements in insulin-stimulated R(d) (~20%) were associated with increased muscle protein content of Akt, TBC1D4, α2-AMP-activated kinase (AMPK), glycogen synthase, hexokinase II and GLUT4 (20-75%). CONCLUSIONS/INTERPRETATION: Impaired insulin-induced site-specific TBC1D4 phosphorylation may contribute to skeletal muscle insulin resistance in type 2 diabetes. The mechanisms by which exercise-training improves insulin sensitivity in type 2 diabetes may involve augmented signalling of TBC1D4 and increased skeletal muscle content of key insulin signalling and effector proteins, e.g., Akt, TBC1D4, AMPK, glycogen synthase, GLUT4 and hexokinase II.

Retracted: 147 reduced syntaxin-5 in skeletal muscle of patients with type 2 diabetes. A link between lipid storage and insulin resistance.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This abstract has been retracted at the request of Jan Borén, co-author, because of conscious fabrication, corruption or suppression of basic material and conscious preparation and presentation of falsified results in the abstract by one of the authors.

Effect of physical training on mitochondrial respiration and reactive oxygen species release in skeletal muscle in patients with obesity and type 2 diabetes.

AIM/HYPOTHESIS: Studies have suggested a link between insulin resistance and mitochondrial dysfunction in skeletal muscles. Our primary aim was to investigate the effect of aerobic training on mitochondrial respiration and mitochondrial reactive oxygen species (ROS) release in skeletal muscle of obese participants with and without type 2 diabetes. METHODS: Type 2 diabetic men (n = 13) and control (n = 14) participants matched for age, BMI and physical activity completed 10 weeks of aerobic training. Pre- and post-training muscle biopsies were obtained before a euglycaemic-hyperinsulinaemic clamp and used for measurement of respiratory function and ROS release in isolated mitochondria. RESULTS: Training significantly increased insulin sensitivity, maximal oxygen consumption and muscle mitochondrial respiration with no difference between groups. When expressed in relation to a marker of mitochondrial density (intrinsic mitochondrial respiration), training resulted in increased mitochondrial ADP-stimulated respiration (with NADH-generating substrates) and decreased respiration without ADP. Intrinsic mitochondrial respiration was not different between groups despite lower insulin sensitivity in type 2 diabetic participants. Mitochondrial ROS release tended to be higher in participants with type 2 diabetes. CONCLUSIONS/INTERPRETATION: Aerobic training improves muscle respiration and intrinsic mitochondrial respiration in untrained obese participants with and without type 2 diabetes. These adaptations demonstrate an increased metabolic fitness, but do not seem to be directly related to training-induced changes in insulin sensitivity.