a multicenter , randomized , single - blind ( subject ) , placebo - controlled , crossover study was performed between 18 january 2011 ( first patient , first visit ) and 28 november 2011 ( last patient , last visit ) with gft505 ( 2-[2,6 dimethyl-4-[3-[4-(methylthio)phenyl]-3-oxo-1(e)-propenyl]phenoxyl]-2-methylpropanoic acid ) , 80 mg ( 4 capsules of 20 mg each once daily before breakfast ) in male patients aged 1875 years ( see supplementary fig . 1 for the study design ) . the duration of each treatment period was 8 weeks , separated by a 6-week wash - out period . the randomization was stratified by site ( center of clinical investigation nantes and centre de recherche en nutrition humaine rhne alpes ) . the primary objective was to evaluate in each patient the differences in glucose infusion rate ( gir ) measured at the second step of a hyperinsulinemic - euglycemic clamp performed at the end of each 8-week treatment period with gft505 or placebo . the secondary objectives included the evaluation of differences in basal and insulin - suppressed endogenous glucose production ( egp ) , fpg , hba1c , plasma lipids including free fatty acids ( ffa ) , liver enzymes , and inflammatory markers at the end of each treatment period . gene expression ( mrna ) was analyzed in muscle tissue biopsy specimens collected once at the end of the first treatment period in the two groups . inclusion criteria were as follows : waist circumference 94 cm ; bmi 45 kg / m ; and homa - ir ( fpg [ mmol / l ]  fasting plasma insulin [ ui / ml]/22.5 ) > 3 . patients had to be consuming stable diets and performing physical exercise within 3 months before screening . main exclusion criteria were uncontrolled hypertension ( blood pressure > 16095 mmhg ) , known heart failure ( new york heart association stage i  iv ) , acute cardiovascular episode 6 months before the start of the study , diabetes mellitus , history of bariatric surgery , and excessive alcohol consumption ( > 3 alcoholic beverage / day ) . biochemical exclusion criteria included fasting plasma tg > 400 mg / dl or ldl cholesterol concentration > 220 mg / dl , thyroid - stimulating hormone more than twice the upper limit of normal , chronic renal failure ( creatinine clearance < 60 ml / min according to modification of diet in renal disease formula or serum creatinine > 180 mol / l ) , active liver disease or hepatic dysfunction as defined by elevations in liver enzymes ( alanine aminotransferase [ alt ] , aspartate aminotransferase , and -glutamyltransferase [ gt ] more than three - times the upper limit of normal ) , and unexplained serum creatine phosphokinase more than twice the upper limit of normal . hypolipidemic drugs were not permitted , except statins ( except fluvastatin ) or ezetimibe , if the dose had been constant and stable at least for 3 months before screening and remained constant during the study . insulin sensitivity was assessed after each treatment period by using the two - step hyperinsulinemic - euglycemic clamp procedure according to defronzo et al . overnight fast , the subjects were admitted to each center ( 0800 h ) and fitted with intravenous catheters placed into the veins in one forearm for insulin and glucose infusion and in the other forearm for blood sampling . the gir was adjusted according to arterialized blood glucose samples measured every 510 min to maintain euglycemia ( 5.0  0.5 mmol / l ) . after a basal period of 2 h , two different flow rates of insulin were used successively : 0.2 mukgmin for the first 2 h and 1.0 mukgmin for the last 2 h. blood samplings were collected each 10 min during the last 30 min of basal period and each insulin infusion step of the clamp to determine glycemia , insulinemia , plasma ffa , tgs , and glucose isotopic enrichment in h. the use of nonradioactive glucose tracer ( deuterated glucose [ 6,6 h2]-glucose ; eurisotop , st . aubin , france ) during the clamp allowed to measure the rate of glucose appearance ( ra ) in basal condition and during the steady state of each insulin infusion period . during the basal period , the amount of tracer infused was based on weight and glycemia of the subject . it included an initial bolus , adjusted by the basal glycemia ( fpg [ g / l ]  80  base flow ) , followed by a constant base flow corresponding to 1% of the theoretical rate of glucose disappearance ( 3 mgkgmin ) . during the hyperinsulinemic clamp , the infusion rate of tracer [ 6.6-h2]-glucose was adapted to glucose infusion to maintain a constant ratio between the labeled glucose and the unlabeled glucose ( 1% ) , corresponding to 0.03 ( first step ) and 0.08 ( second step ) mgkgmin . the exact quantity of tracer infused was determined by weighing the syringe at the beginning and the end of the test . the average rate of glucose infused at steady state of the first level ( 90120 min ) and the second level ( 210240 min ) of the clamp is called gir and is expressed in mgkgmin . flow measurement of glucose turnover was measured in the final 20 min of the basal period ( calculations for times 20 , 10 , and 0 ) . with glycemia stable , the ra corresponds to the basal peripheral glucose utilization ( rd ) and also to the egp . egp ( expressed in mg / kgmin ) was calculated by the following equation : with f indicating flow rate of glucose infused ( mg / kgmin ) and mr indicating molar ratio tracer / traced ( mr% deuterated glucose / natural glucose ) . the biopsy of the vastus lateralis muscle was performed with a bergstrom trocar after local anesthesia of the biopsy area with lidocaine 1% . the biopsy location was identified in the anterolateral side of the thigh , at the junction of the lower - third middle - third through the segment joining the spaced femorotibial and anterior superior iliac spine superior . total rna was extracted using the mirvana mirna isolation kit ( ambion ) following the manufacturer s instructions . after synthesis of complementary dna using moloney murine leukemia virus reverse transcriptase protein , the real - time pcr measurement of individual cdnas was performed using iq sybr green supermix kit to measure duplex dna formation with the iq or myiq real - time pcr detection systems ( bio - rad ) . based on our previous experience ( 22 ) , we assumed the level of gir at the second step of the clamp in moderately insulin - resistant obese patients to be 4.9 mgkgmin with sd of 1.0 mgkgmin , and we assumed the expected gir difference between treatments to be 20% (  = 0.98 mgkgmin ) . with a sample size in each sequence group of 10 ( a total sample size of 20 ) , a 2  2 cross - over design would have 80% power to detect a difference in means of 0.980 ( the difference between a treatment 1 mean , 1 , of 4.900 , and a treatment 2 mean , 2 , of 3.920 ) assuming that the crossover anova mean squares error was 1.000 ( the sd of differences , d , would be 1.414 ) using a two - group t test ( crossover anova ) with a 0.050 two - sided significance level . the main efficacy variable was the difference in gir level after an 8-week period of treatment . a mixed model was built with treatment , period , clinical center , sequence , and interaction of treatment center as fixed factors and patient within sequence as random factor ( carry - over effect ) . given the number of secondary end points , p values between 0.01 and 0.05 should be interpreted cautiously . because muscle biopsies were performed only once per patient , gene expression comparisons were performed using unpaired tests . all coauthors had access to the study data and have reviewed and approved the final manuscript . a multicenter , randomized , single - blind ( subject ) , placebo - controlled , crossover study was performed between 18 january 2011 ( first patient , first visit ) and 28 november 2011 ( last patient , last visit ) with gft505 ( 2-[2,6 dimethyl-4-[3-[4-(methylthio)phenyl]-3-oxo-1(e)-propenyl]phenoxyl]-2-methylpropanoic acid ) , 80 mg ( 4 capsules of 20 mg each once daily before breakfast ) in male patients aged 1875 years ( see supplementary fig . 1 for the study design ) . the duration of each treatment period was 8 weeks , separated by a 6-week wash - out period . the randomization was stratified by site ( center of clinical investigation nantes and centre de recherche en nutrition humaine rhne alpes ) . the primary objective was to evaluate in each patient the differences in glucose infusion rate ( gir ) measured at the second step of a hyperinsulinemic - euglycemic clamp performed at the end of each 8-week treatment period with gft505 or placebo . the secondary objectives included the evaluation of differences in basal and insulin - suppressed endogenous glucose production ( egp ) , fpg , hba1c , plasma lipids including free fatty acids ( ffa ) , liver enzymes , and inflammatory markers at the end of each treatment period . gene expression ( mrna ) was analyzed in muscle tissue biopsy specimens collected once at the end of the first treatment period in the two groups . inclusion criteria were as follows : waist circumference 94 cm ; bmi 45 kg / m ; and homa - ir ( fpg [ mmol / l ]  fasting plasma insulin [ ui / ml]/22.5 ) > 3 . patients had to be consuming stable diets and performing physical exercise within 3 months before screening . main exclusion criteria were uncontrolled hypertension ( blood pressure > 16095 mmhg ) , known heart failure ( new york heart association stage i  iv ) , acute cardiovascular episode 6 months before the start of the study , diabetes mellitus , history of bariatric surgery , and excessive alcohol consumption ( > 3 alcoholic beverage / day ) . biochemical exclusion criteria included fasting plasma tg > 400 mg / dl or ldl cholesterol concentration > 220 mg / dl , thyroid - stimulating hormone more than twice the upper limit of normal , chronic renal failure ( creatinine clearance < 60 ml / min according to modification of diet in renal disease formula or serum creatinine > 180 mol / l ) , active liver disease or hepatic dysfunction as defined by elevations in liver enzymes ( alanine aminotransferase [ alt ] , aspartate aminotransferase , and -glutamyltransferase [ gt ] more than three - times the upper limit of normal ) , and unexplained serum creatine phosphokinase more than twice the upper limit of normal . hypolipidemic drugs were not permitted , except statins ( except fluvastatin ) or ezetimibe , if the dose had been constant and stable at least for 3 months before screening and remained constant during the study . insulin sensitivity was assessed after each treatment period by using the two - step hyperinsulinemic - euglycemic clamp procedure according to defronzo et al . overnight fast , the subjects were admitted to each center ( 0800 h ) and fitted with intravenous catheters placed into the veins in one forearm for insulin and glucose infusion and in the other forearm for blood sampling . the gir was adjusted according to arterialized blood glucose samples measured every 510 min to maintain euglycemia ( 5.0  0.5 mmol / l ) . after a basal period of 2 h , two different flow rates of insulin were used successively : 0.2 mukgmin for the first 2 h and 1.0 mukgmin for the last 2 h. blood samplings were collected each 10 min during the last 30 min of basal period and each insulin infusion step of the clamp to determine glycemia , insulinemia , plasma ffa , tgs , and glucose isotopic enrichment in h. the use of nonradioactive glucose tracer ( deuterated glucose [ 6,6 h2]-glucose ; eurisotop , st . aubin , france ) during the clamp allowed to measure the rate of glucose appearance ( ra ) in basal condition and during the steady state of each insulin infusion period . during the basal period , it included an initial bolus , adjusted by the basal glycemia ( fpg [ g / l ]  80  base flow ) , followed by a constant base flow corresponding to 1% of the theoretical rate of glucose disappearance ( 3 mgkgmin ) . during the hyperinsulinemic clamp , the infusion rate of tracer [ 6.6-h2]-glucose was adapted to glucose infusion to maintain a constant ratio between the labeled glucose and the unlabeled glucose ( 1% ) , corresponding to 0.03 ( first step ) and 0.08 ( second step ) mgkgmin . the exact quantity of tracer infused was determined by weighing the syringe at the beginning and the end of the test . the average rate of glucose infused at steady state of the first level ( 90120 min ) and the second level ( 210240 min ) of the clamp is called gir and is expressed in mgkgmin . flow measurement of glucose turnover was measured in the final 20 min of the basal period ( calculations for times 20 , 10 , and 0 ) . with glycemia stable , the ra corresponds to the basal peripheral glucose utilization ( rd ) and also to the egp . egp ( expressed in mg / kgmin ) was calculated by the following equation : with f indicating flow rate of glucose infused ( mg / kgmin ) and mr indicating molar ratio tracer / traced ( mr% deuterated glucose / natural glucose ) . the biopsy of the vastus lateralis muscle was performed with a bergstrom trocar after local anesthesia of the biopsy area with lidocaine 1% . the biopsy location was identified in the anterolateral side of the thigh , at the junction of the lower - third middle - third through the segment joining the spaced femorotibial and anterior superior iliac spine superior . total rna was extracted using the mirvana mirna isolation kit ( ambion ) following the manufacturer s instructions . after synthesis of complementary dna using moloney murine leukemia virus reverse transcriptase protein , the real - time pcr measurement of individual cdnas was performed using iq sybr green supermix kit to measure duplex dna formation with the iq or myiq real - time pcr detection systems ( bio - rad ) . based on our previous experience ( 22 ) , we assumed the level of gir at the second step of the clamp in moderately insulin - resistant obese patients to be 4.9 mgkgmin with sd of 1.0 mgkgmin , and we assumed the expected gir difference between treatments to be 20% (  = 0.98 mgkgmin ) . with a sample size in each sequence group of 10 ( a total sample size of 20 ) , a 2  2 cross - over design would have 80% power to detect a difference in means of 0.980 ( the difference between a treatment 1 mean , 1 , of 4.900 , and a treatment 2 mean , 2 , of 3.920 ) assuming that the crossover anova mean squares error was 1.000 ( the sd of differences , d , would be 1.414 ) using a two - group t test ( crossover anova ) with a 0.050 two - sided significance level . the main efficacy variable was the difference in gir level after an 8-week period of treatment . a mixed model was built with treatment , period , clinical center , sequence , and interaction of treatment center as fixed factors and patient within sequence as random factor ( carry - over effect ) . given the number of secondary end points , p values between 0.01 and 0.05 should be interpreted cautiously . because muscle biopsies were performed only once per patient , gene expression comparisons were performed using unpaired tests . all coauthors had access to the study data and have reviewed and approved the final manuscript . based on our previous experience ( 22 ) , we assumed the level of gir at the second step of the clamp in moderately insulin - resistant obese patients to be 4.9 mgkgmin with sd of 1.0 mgkgmin , and we assumed the expected gir difference between treatments to be 20% (  = 0.98 mgkgmin ) . with a sample size in each sequence group of 10 ( a total sample size of 20 ) , a 2  2 cross - over design would have 80% power to detect a difference in means of 0.980 ( the difference between a treatment 1 mean , 1 , of 4.900 , and a treatment 2 mean , 2 , of 3.920 ) assuming that the crossover anova mean squares error was 1.000 ( the sd of differences , d , would be 1.414 ) using a two - group t test ( crossover anova ) with a 0.050 two - sided significance level . the main efficacy variable was the difference in gir level after an 8-week period of treatment . a mixed model was built with treatment , period , clinical center , sequence , and interaction of treatment center as fixed factors and patient within sequence as random factor ( carry - over effect ) . given the number of secondary end points , p values between 0.01 and 0.05 should be interpreted cautiously . because muscle biopsies were performed only once per patient , gene expression comparisons were performed using unpaired tests . all coauthors had access to the study data and have reviewed and approved the final manuscript . forty - nine abdominally obese patients were selected to take part in the study . there were 27 screening failures . twenty - six patients did not meet the inclusion criteria and one patient withdrew his consent . all 22 randomized patients received both study treatments and completed the entire study without major protocol deviation . all patients were caucasian males aged 50.2  10.5 years ( see table 1 for baseline characteristics ) . patients were severely insulin - resistant ( mean homa - ir , 5.6  2.3 ) with abdominal obesity ( mean bmi , 32.2  3.4 kg / m ; mean waist circumference , 108.9  9.1 cm ) . patients did not have type 2 diabetes but the mean fpg was moderately elevated at 6.0  0.6 mmol / l . baseline characteristics at screening in this population of nondiabetic subjects , gft505 did not lower fpg concentrations ( table 2 ) . however , gft505 significantly increased the gir both at the first and second steps ( primary end point ) of the hyperinsulinemic - euglycemic clamp , respectively , by 116% ( p = 0.002 ) and 21% ( p = 0.048 ) when compared with placebo , demonstrating an improvement of whole - body insulin sensitivity ( table 3 ) . after an overnight fast , the majority ( 95% ) of egp is derived from the liver ( 23 ) , therefore reflecting the hepatic glucose production . however , during the first insulin infusion period , the suppression of egp compared with baseline levels was 43.5% greater after gft505 than after placebo ( p = 0.006 ) , further indicating an improvement of hepatic insulin action ( table 3 ) . during the second insulin infusion period , egp was fully suppressed in both groups , with values below the limit of detection . the baseline fasting plasma ffa concentrations were reduced on gft505 versus placebo treatment ( 0.40  0.12 vs. 0.46  0.12 mmol / l ; p = 0.025 ) . moreover , insulin suppression of plasma ffa levels during the first insulin infusion period was significantly higher on gft505 treatment ( 0.21  0.07 vs. 0.27 gft505 reduced plasma adiponectin concentrations ( 4,247  2,011 vs. 4,617  2,314 mg / ml ; p = 0.009 ) ( table 2 ) . metabolic and anthropometric parameters after gft505 or placebo treatment periods hepatic and whole - body glucose metabolism during the two - step hyperinsulinemic - euglycemic clamp after 8-week treatment period with gft505 or placebo to further decipher the molecular action of gft505 , skeletal muscle biopsies were performed at the end of the first period of treatment to measure mrna gene expression in placebo - treated ( n = 9 ) and gft505-treated ( n = 9 ) patients ( fig . gft505 failed to increase significantly the expression of ppar and ppar target genes , such as cpt1a , cpt1b , pdk4 , and cd36 . in addition , gft505 did not alter the expression of the insulin - regulated transcription factor srebp1-c or the insulin - responsive glucose transporter 4 . gene ( mrna ) expression in skeletal muscle biopsy specimens at the end of the first 8-week treatment period with gft505 ( 80 mg / day ) or placebo ( n = 9/group ) . values ( means  sd ) are normalized to the expression of 18s and are expressed relative to placebo group . gft505 reduced fasting plasma tg ( relative effect size vs. placebo of 21% ; p = 0.003 ) , ldl cholesterol , and apolipoprotein b ( relative effect size vs. placebo of 13.2% [ p = 0.0006 ] and 14% [ p = 0.003 ] , respectively ) . hdl cholesterol and however , there was a significant increase of apolipoprotein a - ii after gft505 treatment ( relative effect size vs. placebo of + 11.8% ; p = 0.008 ) . all lipid parameters returned to baseline values within 2 weeks after treatment cessation ( data not shown ) . plasma levels of gt , a marker of liver dysfunction , were significantly reduced from baseline by gft505 compared with placebo treatment ( effect size : 30.4% ; p = 0.003 ) . in addition , gft505 significantly decreased alt levels ( effect size : 20.5% ; p = 0.004 ) , with no effect on aspartate aminotransferase concentrations ( effect size : 6.6% ; p = ns ) , suggesting that gft505 can improve nafld in these insulin - resistant subjects ( table 2 ) . a highly significant reduction of alkaline phosphatase levels also was observed after gft505 treatment ( effect size : 19.3% ; p < 0.0001 ) ( table 2 ) . gft505 also led to a modest reduction of haptoglobin ( effect size : 10.1% ; p = 0.03 ) and fibrinogen ( effect size : 15.0% ; p = 0.04 ) levels , with no significant effect on high - sensitivity c - reactive protein concentrations ( table 2 ) . a total of 37 emergent aes were reported during the two treatment periods : 16 aes were reported by 10 patients ( 45% ) in the gft505 group and 21 aes were reported by 15 patients ( 61% ) in the placebo group ( supplementary table 2 ) . among these aes , of them , four were reported with gft505 ( one case of upper gastrointestinal pain , one case of fatigue , one case of eczema , and one case of abnormal sweating ) and eight were reported with placebo ( supplementary table 3 ) . no ae led to the discontinuation of gft505 and no serious ae related to gft505 was reported . six additional aes were reported during the 6-week wash - out period and eight were reported during the 2-week follow - up period ; none of them was judged related to gft505 . only one serious ae ( femoral neck fracture of the left hip after an accidental fall ) was reported during the course of the study concerning one patient during treatment with placebo . no abnormal evolution of laboratory values , vital signs , or electrocardiograms was observed during the treatment periods . all safety parameters including hematological parameters , plasma creatinine , creatine phosphokinase , and homocysteine concentrations remained unaltered during the gft505 treatment period ( table 2 ) . forty - nine abdominally obese patients were selected to take part in the study . there were 27 screening failures . twenty - six patients did not meet the inclusion criteria and one patient withdrew his consent . all 22 randomized patients received both study treatments and completed the entire study without major protocol deviation . all patients were caucasian males aged 50.2  10.5 years ( see table 1 for baseline characteristics ) . patients were severely insulin - resistant ( mean homa - ir , 5.6  2.3 ) with abdominal obesity ( mean bmi , 32.2  3.4 kg / m ; mean waist circumference , 108.9  9.1 cm ) . patients did not have type 2 diabetes but the mean fpg was moderately elevated at 6.0  0.6 mmol / l . baseline characteristics at screening in this population of nondiabetic subjects , gft505 did not lower fpg concentrations ( table 2 ) . however , gft505 significantly increased the gir both at the first and second steps ( primary end point ) of the hyperinsulinemic - euglycemic clamp , respectively , by 116% ( p = 0.002 ) and 21% ( p = 0.048 ) when compared with placebo , demonstrating an improvement of whole - body insulin sensitivity ( table 3 ) . after an overnight fast , the majority ( 95% ) of egp is derived from the liver ( 23 ) , therefore reflecting the hepatic glucose production . however , during the first insulin infusion period , the suppression of egp compared with baseline levels was 43.5% greater after gft505 than after placebo ( p = 0.006 ) , further indicating an improvement of hepatic insulin action ( table 3 ) . during the second insulin infusion period , egp was fully suppressed in both groups , with values below the limit of detection . the baseline fasting plasma ffa concentrations were reduced on gft505 versus placebo treatment ( 0.40  0.12 vs. 0.46  0.12 mmol / l ; p = 0.025 ) . moreover , insulin suppression of plasma ffa levels during the first insulin infusion period was significantly higher on gft505 treatment ( 0.21  0.07 vs. 0.27 gft505 reduced plasma adiponectin concentrations ( 4,247  2,011 vs. 4,617  2,314 mg / ml ; p = 0.009 ) ( table 2 ) . metabolic and anthropometric parameters after gft505 or placebo treatment periods hepatic and whole - body glucose metabolism during the two - step hyperinsulinemic - euglycemic clamp after 8-week treatment period with gft505 or placebo to further decipher the molecular action of gft505 , skeletal muscle biopsies were performed at the end of the first period of treatment to measure mrna gene expression in placebo - treated ( n = 9 ) and gft505-treated ( n = 9 ) patients ( fig . 1 ) . gft505 failed to increase significantly the expression of ppar and ppar target genes , such as cpt1a , cpt1b , pdk4 , and cd36 . in addition , gft505 did not alter the expression of the insulin - regulated transcription factor srebp1-c or the insulin - responsive glucose transporter 4 . gene ( mrna ) expression in skeletal muscle biopsy specimens at the end of the first 8-week treatment period with gft505 ( 80 mg / day ) or placebo ( n = 9/group ) . values ( means  sd ) are normalized to the expression of 18s and are expressed relative to placebo group . gft505 reduced fasting plasma tg ( relative effect size vs. placebo of 21% ; p = 0.003 ) , ldl cholesterol , and apolipoprotein b ( relative effect size vs. placebo of 13.2% [ p = 0.0006 ] and 14% [ p = 0.003 ] , respectively ) . hdl cholesterol and however , there was a significant increase of apolipoprotein a - ii after gft505 treatment ( relative effect size vs. placebo of + 11.8% ; p = 0.008 ) . all lipid parameters returned to baseline values within 2 weeks after treatment cessation ( data not shown ) . plasma levels of gt , a marker of liver dysfunction , were significantly reduced from baseline by gft505 compared with placebo treatment ( effect size : 30.4% ; p = 0.003 ) . in addition , gft505 significantly decreased alt levels ( effect size : 20.5% ; p = 0.004 ) , with no effect on aspartate aminotransferase concentrations ( effect size : 6.6% ; p = ns ) , suggesting that gft505 can improve nafld in these insulin - resistant subjects ( table 2 ) . a highly significant reduction of alkaline phosphatase levels also was observed after gft505 treatment ( effect size : 19.3% ; p < 0.0001 ) ( table 2 ) . gft505 also led to a modest reduction of haptoglobin ( effect size : 10.1% ; p = 0.03 ) and fibrinogen ( effect size : 15.0% ; p = 0.04 ) levels , with no significant effect on high - sensitivity c - reactive protein concentrations ( table 2 ) . a total of 37 emergent aes were reported during the two treatment periods : 16 aes were reported by 10 patients ( 45% ) in the gft505 group and 21 aes were reported by 15 patients ( 61% ) in the placebo group ( supplementary table 2 ) . among these aes , 12 were considered as possibly related to the study treatment by the investigators . of them , four were reported with gft505 ( one case of upper gastrointestinal pain , one case of fatigue , one case of eczema , and one case of abnormal sweating ) and eight were reported with placebo ( supplementary table 3 ) . no ae led to the discontinuation of gft505 and no serious ae related to gft505 was reported . six additional aes were reported during the 6-week wash - out period and eight were reported during the 2-week follow - up period ; none of them was judged related to gft505 . only one serious ae ( femoral neck fracture of the left hip after an accidental fall ) was reported during the course of the study concerning one patient during treatment with placebo . no abnormal evolution of laboratory values , vital signs , or electrocardiograms was observed during the treatment periods . all safety parameters including hematological parameters , plasma creatinine , creatine phosphokinase , and homocysteine concentrations remained unaltered during the gft505 treatment period ( table 2 ) . the present randomized study , using the gold standard hyperinsulinemic - euglycemic clamp method , clearly demonstrates that gft505 is a new insulin - sensitizer that improves both peripheral and hepatic insulin sensitivity in insulin - resistant abdominally obese subjects . in accordance with a hepatic insulin - sensitizing action gft505 also improved plasma lipid parameters , significantly decreasing both tg and ldl cholesterol levels . finally , the safety profile of gft505 was good , with no reported serious ae . in clinical practice , tzds remain the most efficacious insulin - sensitizing drugs that improve both hepatic and peripheral insulin sensitivity ( 8,9,24 ) . in parallel , tzds reduce liver fat in patients with type 2 diabetes with or without nonalcoholic steatohepatitis ( 8,2527 ) . metformin is a biguanide that acts by inhibiting mitochondrial complex i , leading to reduced hepatic mitochondrial atp production and gluconeogenesis rates ( 7 ) . in contrast to tzds , several studies indicate that metformin fails to improve peripheral insulin sensitivity and to reduce liver fat content ( 7,24,28 ) . compared with placebo , gft505 improved simultaneously the gir by 21% during the second insulin infusion period and the suppression of egp by 43% during the first insulin infusion period of the hyperinsulinemic - euglycemic clamp . the extent of the gir increase on gft505 treatment seems to be in a range similar to that observed in two placebo - controlled studies with pioglitazone , one in prediabetic subjects with coronary heart disease ( + 12.5% ) ( 29 ) and the second in nondiabetic subjects with combined hyperlipidemia ( + 33% ) ( 30 ) . although our data demonstrate that gft505 is a new potent insulin sensitizer , only a head - to - head trial will allow a reliable comparison between these two drugs . gft505 also enhanced insulin suppression of ffa levels , indicating a global insulin - sensitizing effect on muscle , liver , and adipose tissue . in agreement with previous clinical ( 20 ) and animal studies , there is no evidence of ppar activity of gft505 in this study either . in diabetic db / db mice , 58-day treatment with gft505 produced a similar decrease in fpg and hba1c as rosiglitazone , but without increasing plasma adiponectin concentrations and without inducing the expression of ppar target genes in adipose tissue ( data not shown ) . here , we confirm that gft505 does not increase plasma adiponectin concentrations in humans either . in contrast , a significant reduction of adiponectin levels is even observed on gft505 treatment , suggesting that gft505 either improves adiponectin signaling or exerts its effects in an adiponectin - independent manner . thus , together with the low affinity and partial agonist activity of gft505 on ppar , as well as the large enterohepatic cycling and liver - targeted pharmacodynamics of gft505 ( as illustrated by the lack of gene regulation effects in skeletal muscle ) , our data seem to exclude insulin - sensitizing effects resulting from ppar activation in adipose tissue . the insulin - sensitizing effect of gft505 could be linked to its ppar or combined ppar/ppar activity . in three randomized hyperinsulinemic - euglycemic clamp studies , the pure ppar agonist fenofibrate failed to improve either peripheral or hepatic insulin sensitivity in patients with the metabolic syndrome ( 12 ) , nafld ( 13 ) , or type 2 diabetes ( 14 ) . in contrast , it has been demonstrated that the pure ppar agonist gw501516 significantly reduces homa - ir in abdominally obese patients ( 16 ) . however , to the best of our knowledge , the current study is the first to directly demonstrate that combined ppar/ppar activation leads to an improvement of insulin sensitivity in humans . to explore the molecular mechanisms whereby gft505 improves insulin sensitivity , skeletal muscle biopsies were performed at the end of the first treatment period . because muscle biopsies were performed only once per patient during the study , gene expression comparisons were unpaired and may lack power . pharmacological activation of ppar with gw501516 increases fatty acid oxidation in skeletal muscle and improves metabolism in mice ( 15,16 ) . in addition , ppar activation with specific synthetic agonists also enhances fatty acid oxidation and oxidative gene expression ( 31 ) , as well as basal and insulin - stimulated glucose uptake in primary human myotubes ( 32 ) . in human skeletal muscle biopsy specimens in contrast , gft505 failed to induce the expression of several ppar target genes ( cpt1b , pdk4 , cd36 ) in muscle biopsy specimens . therefore , it seems unlikely that a direct activation of ppar in skeletal muscle contributes to the insulin - sensitizing action of gft505 in vivo . moreover , gft505 does not induce ppar/ target genes ( cpt1 and pdk4 ) in skeletal muscles of diabetic db / db mice either ( data not shown ) . these results are in accordance with the pharmacokinetics of gft505 , which is a liver - targeted drug that undergoes extensive enterohepatic cycling ( 19 ) . thus , additional studies are needed to unravel the precise molecular mechanism behind the peripheral insulin - sensitizing effect of gft505 . interestingly , gft505 improved insulin suppression of plasma ffa levels during the first step of the hyperinsulinemic - euglycemic clamp , an effect potentially contributing to the improvement in peripheral insulin sensitivity , possibly by reducing intramyocellular lipotoxicity ( 33 ) . a similar reduction of circulating ffa has been previously observed in subjects with abdominal obesity treated with ppar agonists ( 18,34,35 ) . in contrast , ppar agonists , such as fenofibrate , reduced fasting plasma ffa levels in some ( 12,13 ) , but not all , studies ( 14 ) . however , overall fenofibrate fails to improve glucose homeostasis in type 2 diabetes ( 14,36 ) . in a direct comparison with the ppar agonist gw501516 , the pure ppar agonist gw590735 also failed to decrease fasting plasma ffa concentrations ( 18 ) . finally , insulin suppression of circulating ffa was not modified by fenofibrate in several clamp studies ( 12,14 ) . the enhanced insulin suppression of plasma ffa levels with gft505 suggests improved insulin sensitivity in adipocytes . unfortunately , we did not sample adipose tissue biopsy specimens during the study ; therefore , we are unable to determine whether gft505 can directly activate ppar target genes in adipose tissue . alternatively , the decrease in circulating ffa after gft505 treatment could be attributable to an increase in ffa uptake and -oxidation in the liver . therefore , additional studies are needed to unravel the mechanism of action of gft505 on ffa metabolism . an intriguing finding of our study is that gft505 reduces both gt ( 30% ) and alt ( 20% ) levels , suggesting an improvement in liver function in these severely insulin - resistant subjects . these data are in line with previous studies with gft505 ( 20 ) and selective ppar agonists in pilot studies ( 18,35 ) . eight weeks of treatment with the ppar agonist mbx-8025 ( 100 mg / d ) reduced gt by 28% in overweight men with mixed dyslipidemia ( 35 ) . in addition , 2 weeks of treatment with the ppar agonist gw501516 decreased gt by 23% in moderately obese men , without improving alt . interestingly , gw501516 also reduced liver fat content by 20% ( 18 ) , and this effect correlated with the change in gt levels ( 18 ) . the decrease of hepatic steatosis after ppar activation by gw501516 could be attributable to the reduced flux of ffa from adipose tissue or an increase in ffa uptake and -oxidation in the liver . in contrast , there is no evidence for a beneficial role of ppar agonists in human nafld because fenofibrate does not improve transaminase levels or hepatic fat content in several randomized studies ( 1214 ) . in contrast to what is observed with ppar agonists , there was neither body weight gain nor fluid retention . in addition , there were no significant increases in plasma creatinine or homocysteine levels , which are some classical ppar-related side effects ( 37 ) . the duration of treatment remains too short to assess the long - term safety of the drug . in addition , statistical significance of secondary end points should be interpreted cautiously because of multiple comparisons . a measure of glucose / lipid oxidation by indirect calorimetry may allow determining the effect of gft505 on ffa oxidation . a direct measure of liver fat content is lacking to reinforce the hypothesis that gft505 improves nafld by reducing liver steatosis . in conclusion , this study demonstrates that the dual ppar/ agonist gft505 is a new insulin sensitizer that exerts a beneficial impact on multiple components of the metabolic syndrome , including hepatic and peripheral insulin resistance , dyslipidemia , inflammation , and possibly nafld . many of these effects seem to be mediated by a combined activation of ppar and ppar into the liver , but the precise mode of action of gft505 remains to be further determined . based on the results of this study and previous clinical trials , a randomized , double - blind , placebo - controlled , 1-year phase iib study ( clinicaltrials.gov identifier nct01694849 ) is currently ongoing and will assess the efficacy and safety of gft505 in patients with histologically proven nonalcoholic steatohepatitis .
objectivethe development of new insulin sensitizers is an unmet need for the treatment of type 2 diabetes . 
 we investigated the effect of gft505 , a dual peroxisome proliferator  activated receptor ( ppar)-/ agonist , on peripheral and hepatic insulin sensitivity.research design and methodstwenty - two abdominally obese insulin - resistant males ( homeostasis model assessment of insulin resistance > 3 ) were randomly assigned in a randomized crossover study to subsequent 8-week treatment periods with gft505 ( 80 mg / day ) or placebo , followed by a two - step hyperinsulinemic - euglycemic insulin clamp with a glucose tracer to calculate endogenous glucose production ( egp ) . 
 the primary end point was the improvement in glucose infusion rate ( gir ) . 
 gene expression analysis was performed on skeletal muscle biopsy specimens.resultsgft505 improved peripheral insulin sensitivity , with a 21% ( p = 0.048 ) increase of the gir at the second insulin infusion period . 
 gft505 also enhanced hepatic insulin sensitivity , with a 44% ( p = 0.006 ) increase of insulin suppression of egp at the first insulin infusion period . 
 insulin - suppressed plasma free fatty acid concentrations were significantly reduced on gft505 treatment ( 0.21  0.07 vs. 0.27  0.11 mmol / l ; p = 0.006 ) . 
 neither ppar nor ppar target genes were induced in skeletal muscle , suggesting a liver - targeted action of gft505 . 
 gft505 significantly reduced fasting plasma triglycerides ( 21% ; p = 0.003 ) and ldl cholesterol ( 13% ; p = 0.0006 ) , as well as liver enzyme concentrations ( -glutamyltranspeptidase : 30.4% , p = 0.003 ; alanine aminotransferase : 20.5% , p = 0.004 ) . 
 there was no safety concern or any indication of ppar activation with gft505.conclusionsthe dual ppar/ agonist gft505 is a liver - targeted insulin - sensitizer that is a promising drug candidate for the treatment of type 2 diabetes and nonalcoholic fatty liver disease .