twenty - three pgdm and eight women without any risk factors for type 2 diabetes serving as controls ( con ) were recruited from the outpatient service of the division of endocrinology and metabolism , department of internal medicine iii , medical university of vienna . gdm was diagnosed according to the criteria of the fourth workshop conference of gestational diabetes . the women were continuously seen in the outpatient service so that all data on diagnosis and treatment were recorded and validated . fifteen pgdm had been on insulin therapy ( it ) , and eight pgdm had been on diet treatment ( dt ) only . they were instructed to ingest an isocaloric diet ( carbohydrate / protein / fat : 60/20/20% ) and refrain from any physical exercise during the 3 days preceding the examinations . metabolic tests were performed on different days during the first phase ( days 58 ) of the menstrual cycle after 1012-h overnight fasting . all participants gave written informed consent to the protocol , which had been approved by the institutional ethics board of the medical university of vienna . a solution containing 75 g of glucose was ingested within 2 min , and venous blood samples were collected for measurements of glucose and hormones . during fasting , insulin sensitivity was assessed with the quantitative insulin - sensitivity check index ( quicki ) = 1/[log(fasting - glucose ) + log(fasting - insulin ) ] , which mostly indicates hepatic insulin sensitivity ( 11 ) . under dynamic conditions , the oral glucose insulin sensitivity ( ogis ) index ( 12 ) was used , which quantifies glucose clearance per unit change of insulin and has been validated against the glucose clamp ( 12,13 ) and in terms of reproducibility and variability ( 14 ) . the ogis correlates more closely with total glucose disposal than with hepatic insulin sensitivity in a study directly comparing the glucose clamp with the oral glucose tolerance test ( ogtt ) ( 11 ) . thus , we used ogis as a measure of whole - body insulin sensitivity during glucose ingestion . insulin delivered into peripheral circulation was assessed with the total area under the insulin concentration curve ( aucins ) , calculated with the trapezoidal rule . an integrated index of -cell function ( adaptation index ) , as its ability to compensate insulin resistance by increasing insulin release , was calculated as ogis  auccp , where auccp is the suprabasal area under the c - peptide concentration curve . in addition , the frequent sampling intravenous glucose tolerance test was performed and analyzed for assessing si as a measure of insulin sensitivity and disposition index , di = si  airgluc as a measure of combined effects of insulin secretion and sensitivity on glucose disposal as described previously ( 15 ) . measurements were performed in participants lying supine inside a 3-t whole - body spectrometer ( bruker biospin , ettlingen , germany ) . 1 ) p mrs ( magnetic resonance spectroscopy ) : a 10-cm circular double - resonant surface coil was positioned over the medial head of the right gastrocnemius muscle . intramyocellular concentrations of inorganic phosphate and atp , as well as rate constant ( katp ) and unidirectional fatpase , using the saturation transfer experiment , were measured as described ( 4,16 ) . 2 ) h mrs : a 10-cm , circular , double - resonant surface coil was applied above the right soleus muscle to measure imcl from localized h spectra using the series stimulated echo acquisition mode sequence within a volume of interest of 1.73 cm ( 5 ) . hcl were quantified using the stimulated echo acquisition mode within a volume of interest of 27 cm ( 5 ) . body fat mass ( bfm ) was assessed from bioimpedance analysis ( akern - rjl systems , florence , italy ) . prediction errors of body composition equations estimating percent fat free mass are based on empirically derived measurement errors associated with the reference method , hydrodensitometry . resting energy expenditure ( ree ) tokyo , japan ) , hba1c ( a1c ) was measured by high - performance liquid chromatography ( variant hemoglobin testing system , hercules , ca ) , and ultrasensitive c - reactive protein was measured by particle - enhanced immunonephelometry ( n high - sensitivity - crp reagent , bn systems ; dade behring , deerfield , il ) . fasting plasma adiponectin was measured in duplicate using an enzyme - linked immunosorbent assay system ( otsuka pharmaceutical co. ltd . relationships among fatpase , imcl , hcl , insulin sensitivity , and metabolic and inflammatory parameters were further analyzed in pgdm and con , insulin - sensitive ( is ) subjects ( n = 15 ) , insulin - resistant ( ir ) subjects ( n = 16 ) , insulin - sensitive ( pgdm - is , n = 9 ) , and insulin - resistant pgdm ( pgdm - ir , n = 14 ) . the cutoff value ( 462.8 ml m ) for insulin resistance was derived from ogis values in control women of this study and other studies . the lowest quantile of the distribution gave the value defined as cutoff point between normal and impaired ( lower ) ogis . further , all women and pgdm were divided into three groups according to ogis tertiles . data are presented as means  sd in text and tables or box - and - whisker plots in figures . the tukey test was applied for post hoc testing , and the wilcoxon rank - sum test was applied for nonparametric parameters . twenty - three pgdm and eight women without any risk factors for type 2 diabetes serving as controls ( con ) were recruited from the outpatient service of the division of endocrinology and metabolism , department of internal medicine iii , medical university of vienna . gdm was diagnosed according to the criteria of the fourth workshop conference of gestational diabetes . the women were continuously seen in the outpatient service so that all data on diagnosis and treatment were recorded and validated . fifteen pgdm had been on insulin therapy ( it ) , and eight pgdm had been on diet treatment ( dt ) only . they were instructed to ingest an isocaloric diet ( carbohydrate / protein / fat : 60/20/20% ) and refrain from any physical exercise during the 3 days preceding the examinations . metabolic tests were performed on different days during the first phase ( days 58 ) of the menstrual cycle after 1012-h overnight fasting . all participants gave written informed consent to the protocol , which had been approved by the institutional ethics board of the medical university of vienna . a solution containing 75 g of glucose was ingested within 2 min , and venous blood samples were collected for measurements of glucose and hormones . during fasting , insulin sensitivity was assessed with the quantitative insulin - sensitivity check index ( quicki ) = 1/[log(fasting - glucose ) + log(fasting - insulin ) ] , which mostly indicates hepatic insulin sensitivity ( 11 ) . under dynamic conditions , the oral glucose insulin sensitivity ( ogis ) index ( 12 ) was used , which quantifies glucose clearance per unit change of insulin and has been validated against the glucose clamp ( 12,13 ) and in terms of reproducibility and variability ( 14 ) . the ogis correlates more closely with total glucose disposal than with hepatic insulin sensitivity in a study directly comparing the glucose clamp with the oral glucose tolerance test ( ogtt ) ( 11 ) . thus , we used ogis as a measure of whole - body insulin sensitivity during glucose ingestion . insulin delivered into peripheral circulation was assessed with the total area under the insulin concentration curve ( aucins ) , calculated with the trapezoidal rule . an integrated index of -cell function ( adaptation index ) , as its ability to compensate insulin resistance by increasing insulin release , was calculated as ogis  auccp , where auccp is the suprabasal area under the c - peptide concentration curve . in addition , the frequent sampling intravenous glucose tolerance test was performed and analyzed for assessing si as a measure of insulin sensitivity and disposition index , di = si  airgluc as a measure of combined effects of insulin secretion and sensitivity on glucose disposal as described previously ( 15 ) . measurements were performed in participants lying supine inside a 3-t whole - body spectrometer ( bruker biospin , ettlingen , germany ) . 1 ) p mrs ( magnetic resonance spectroscopy ) : a 10-cm circular double - resonant surface coil was positioned over the medial head of the right gastrocnemius muscle . intramyocellular concentrations of inorganic phosphate and atp , as well as rate constant ( katp ) and unidirectional fatpase , using the saturation transfer experiment , were measured as described ( 4,16 ) . 2 ) h mrs : a 10-cm , circular , double - resonant surface coil was applied above the right soleus muscle to measure imcl from localized h spectra using the series stimulated echo acquisition mode sequence within a volume of interest of 1.73 cm ( 5 ) . hcl were quantified using the stimulated echo acquisition mode within a volume of interest of 27 cm ( 5 ) . body fat mass ( bfm ) was assessed from bioimpedance analysis ( akern - rjl systems , florence , italy ) . prediction errors of body composition equations estimating percent fat free mass are based on empirically derived measurement errors associated with the reference method , hydrodensitometry . resting energy expenditure ( ree ) tokyo , japan ) , hba1c ( a1c ) was measured by high - performance liquid chromatography ( variant hemoglobin testing system , hercules , ca ) , and ultrasensitive c - reactive protein was measured by particle - enhanced immunonephelometry ( n high - sensitivity - crp reagent , bn systems ; dade behring , deerfield , il ) . fasting plasma adiponectin was measured in duplicate using an enzyme - linked immunosorbent assay system ( otsuka pharmaceutical co. ltd . , relationships among fatpase , imcl , hcl , insulin sensitivity , and metabolic and inflammatory parameters were further analyzed in pgdm and con , insulin - sensitive ( is ) subjects ( n = 15 ) , insulin - resistant ( ir ) subjects ( n = 16 ) , insulin - sensitive ( pgdm - is , n = 9 ) , and insulin - resistant pgdm ( pgdm - ir , n = 14 ) . the cutoff value ( 462.8 ml  min m ) for insulin resistance was derived from ogis values in control women of this study and other studies . the lowest quantile of the distribution gave the value defined as cutoff point between normal and impaired ( lower ) ogis . further , all women and pgdm were divided into three groups according to ogis tertiles . statistical analyses were performed using sas software 9.1.3 ( sas institute , inc . , cary , nc ) . data are presented as means  sd in text and tables or box - and - whisker plots in figures . the tukey test was applied for post hoc testing , and the wilcoxon rank - sum test was applied for nonparametric parameters . all women had normal glucose tolerance based on the 75-g ogtt and comparable habitual physical activities according to baecke s questionnaire ( table 1 ) . this also held true for pgdm - ir , but not for pgdm - is . adjustment for clinical characteristics and metabolic parameters ( means  sd ) of women with pgdm and their insulin - resistant ( pgdm - ir ) and insulin - sensitive ( pgdm - is ) subgroups compared with control subjects ( con ) ir was defined by means of ogis < 462.8 ml  min  m. ggt , gamma glutamyl transferase ; us - crp , ultra - sensitive c - reactive protein . pgdm had marginally higher postload glycemia ( table 2 ) and lower ogis than con ( fig . , ogis was 21% lower ( p < 0.007 ) in the insulin resistant than in the insulin sensitive subgroup . after adjustment for bfm , the difference in ogis between pgdm - ir and pgdm - is remained ( adjusted means : 408 ml  min  m vs. 513 ml  min  m ; p < 0.0001 ) and tended to be lower even in pgdm - is compared with con ( adjusted means : 412 ml  min  m vs. 514 ml  min  m ; p = 0.06 ) . the intergroup difference for postload glycemia disappeared . insulin delivery ( aucins ) was higher in pgdm - ir compared with pgdm - is ( table 2 ) . the adaptation index was not different between pgdm and con , reflecting normal glucose tolerance due to adequate -cell compensation for a minor degree of insulin resistance in pgdm ( data not shown ) . fasting c - peptide reflecting basal insulin secretion rates and aucgluc were higher in pgdm - ir than in pgdm - is ( p < 0.05 and p = 0.0007 ; table 2 ) , although these differences disappeared after adjustment for bfm . glucose metabolism , insulin sensitivity , and secretion ( all expressed as means  sd ) in women with pgdm and their insulin - resistant ( pgdm - ir ) and insulin - sensitive ( pgdm - is ) subgroups compared with control subjects ( con ) ir was defined by means of ogis < 462.8 ml  min  m. fasting ffa , basal free fatty acid ; 2-h ffa , free fatty acid at 120 min ; quicki , quantitative insulin - sensitivity check index ; aucgluc , area under the glucose concentration curve ; aucins , area under the insulin concentration curve . myocellular fatpase ( a and c ) and insulin sensitivity ( b and d ) as assessed from the ogtt ( ogis ) in pgdm compared with con ( a and b ) and in ir and is subgroups of the total cohort according to their insulin sensitivity ( ogis ) ( c and d ) . boxes delineate lower and upper quartile , whiskers represent minima and maxima , medians are indicated by solid line within boxes , and small circles / asterisks represent experimental outliers . fatpase : pgdm vs. con ( 10.6  3.8 mol  ml muscle  min vs. 12.1  1.4 mol  ml muscle  min ; p < 0.12 , * * after log transformation : p < 0.03 ) , ogis ( glucose clearance ) : pgdm vs. con ( 447  67 ml  min  m vs. 508  87 ml  min  m ; p < 0.05 ) , fatpase : ir vs. is ( 10.7  3.7 mol  ml muscle  min vs. 11.4  3.0 mol  ml muscle  min ; p = 0.6 ns ) , ogis ( glucose clearance ) : ir vs. is ( 402  38 ml  min  m vs. 528  46 ml  min  m ; p < 0.0001 ) . 1a ) only on log - transformation of the data ( p < 0.03 ) , which had to be performed because of outliers . adjusting for bfm diminished the difference ( p = 0.37 ) . interestingly , fatpase did not differ between the ir and is subgroups of pgdm and the total population ( p = 0.30 ; fig . further , fatpase did not differ between lowest and highest ogis tertiles , both in all women ( p > 0.2 ) and in pgdm alone ( p > 0.4 ) . katp was not different between pgdm and con ( 0.06  0.02 1/s vs. 0.07  0.01 1/s ; p = 0.1 ) or between subgroups ( pgdm - ir vs. pgdm - is : 0.06  0.02 1/s vs. 0.06  0.02 1/s ; p = 0.6 ) . fatpase was also comparable between pgdm with and without insulin therapy ( it ) during their pregnancies . 2a ) , but 61% higher in pgdm - ir than in pgdm - is ( p < 0.05 ) . among all women , ir women had 69% higher imcl than is women ( p < 0.007 ; fig . pgdm on it during their pregnancies had higher imcl than those on diet treatment ( dt ) ( it vs. dt : 0.86  0.29% vs. 0.51  0.25% , p = 0.01 ) . imcl and hcl . ectopic lipids in skeletal muscle ( imcl ; a and c ) and liver ( hcl ; b and d ) of pgdm compared with con ( a and b ) and in ir and is subgroups of the total cohort according to their insulin sensitivity ( ogis ) ( c and d ) . boxes delineate lower and upper quartile , whiskers represent minima and maxima , respectively , medians are indicated by solid line within boxes , and small circles / asterisks represent experimental outliers . imcl : pgdm vs. con ( 0.73  0.32% h2o vs. 0.69  0.5% h2o ; p = 0.08 ns ) hcl : pgdm vs. con ( 3.7  3.5% vs. 1.5  0.9% signal ; p < 0.05 ) imcl : ir vs. is ( 0.90  0.3% h2o vs. 0.54  0.32% h2o ; p < 0.003 ) hcl : ir vs. is ( 4.0  3.3% vs. 2.0  1.8% signal ; p < 0.05 ) . likewise , hcl were twice as high in ir than in is subjects ( p < 0.05 ; fig . 2d ) , but not different among pgdm subgroups . adjusting for bfm diminished these differences . hcl were not different between pgdm with or without it during pregnancy ( dt vs. it : hcl 4.8  5.0% signal vs. 3.1  2.4% signal ) . partial correlation analysis , controlled for bfm , revealed a relationship between fatpase and plasma adiponectin across all women ( p < 0.04 , r = 0.44 ) . fatpase did not relate to measures of insulin sensitivity ( ogis : r = 0.002 , si : r = 0.07 ) or glucose tolerance ( aucgluc : r = 0.005 ) in any subgroup . however , the disposition index related to hcl ( r = 0.59 , p = 0.002 ) and fatpase ( r = 0.37 , p = 0.04 ) in all women . fasting plasma ffa did not relate to fatpase , whereas 2-h postload plasma ffa related to hcl ( r = 0.59 , p = 0.01 ) and insulin sensitivity as assessed from ogis ( r = 0.44 , p = 0.04 ) or si ( r = 0.42 , p = 0.04 ) in pgdm . hcl related to insulin sensitivity ( r = 0.47 , p < 0.02 ) across all women and to imcl ( r = 0.59 , p = 0.05 ) and a1c across ir ( r = 0.64 , p < 0.03 ) . after adjustment for bfm , hcl still related to a1c ( r = 0.57 , p < 0.02 ) in all women . within pgdm , the correlation of hcl with hip circumference ( r = 0.59 , p = 0.04 ) and a1c ( r = 0.62 , p = 0.03 ) remained after adjustment for bfm . all women had normal glucose tolerance based on the 75-g ogtt and comparable habitual physical activities according to baecke s questionnaire ( table 1 ) . this also held true for pgdm - ir , but not for pgdm - is . adjustment for clinical characteristics and metabolic parameters ( means  sd ) of women with pgdm and their insulin - resistant ( pgdm - ir ) and insulin - sensitive ( pgdm - is ) subgroups compared with control subjects ( con ) ir was defined by means of ogis < 462.8 ml  min  m. ggt , gamma glutamyl transferase ; us - crp , ultra - sensitive c - reactive protein . pgdm had marginally higher postload glycemia ( table 2 ) and lower ogis than con ( fig . , ogis was 21% lower ( p < 0.007 ) in the insulin resistant than in the insulin sensitive subgroup . after adjustment for bfm , the difference in ogis between pgdm - ir and pgdm - is remained ( adjusted means : 408 ml  min  m vs. 513 ml  min  m ; p < 0.0001 ) and tended to be lower even in pgdm - is compared with con ( adjusted means : 412 ml  min  m vs. 514 ml  min  m ; p = 0.06 ) . insulin delivery ( aucins ) was higher in pgdm - ir compared with pgdm - is ( table 2 ) . the adaptation index was not different between pgdm and con , reflecting normal glucose tolerance due to adequate -cell compensation for a minor degree of insulin resistance in pgdm ( data not shown ) . fasting c - peptide reflecting basal insulin secretion rates and aucgluc were higher in pgdm - ir than in pgdm - is ( p < 0.05 and p = 0.0007 ; table 2 ) , although these differences disappeared after adjustment for bfm . glucose metabolism , insulin sensitivity , and secretion ( all expressed as means  sd ) in women with pgdm and their insulin - resistant ( pgdm - ir ) and insulin - sensitive ( pgdm - is ) subgroups compared with control subjects ( con ) ir was defined by means of ogis < 462.8 ml  min  m. fasting ffa , basal free fatty acid ; 2-h ffa , free fatty acid at 120 min ; quicki , quantitative insulin - sensitivity check index ; aucgluc , area under the glucose concentration curve ; aucins , area under the insulin concentration curve . myocellular fatpase ( a and c ) and insulin sensitivity ( b and d ) as assessed from the ogtt ( ogis ) in pgdm compared with con ( a and b ) and in ir and is subgroups of the total cohort according to their insulin sensitivity ( ogis ) ( c and d ) . boxes delineate lower and upper quartile , whiskers represent minima and maxima , medians are indicated by solid line within boxes , and small circles / asterisks represent experimental outliers . fatpase : pgdm vs. con ( 10.6  3.8 mol  ml muscle  min vs. 12.1  1.4 mol  ml muscle  min ; p < 0.12 , * * after log transformation : p < 0.03 ) , ogis ( glucose clearance ) : pgdm vs. con ( 447  67 ml  min  m vs. 508  87 ml  min  m ; p < 0.05 ) , fatpase : ir vs. is ( 10.7  3.7 mol  ml muscle  min vs. 11.4  3.0 mol  ml muscle  min ; p = 0.6 ns ) , ogis ( glucose clearance ) : ir vs. is ( 402  38 ml  min  m vs. 528  46 ml  min  m ; p < 0.0001 ) . 1a ) only on log - transformation of the data ( p < 0.03 ) , which had to be performed because of outliers . adjusting for bfm diminished the difference ( p = 0.37 ) . interestingly , fatpase did not differ between the ir and is subgroups of pgdm and the total population ( p = 0.30 ; fig . further , fatpase did not differ between lowest and highest ogis tertiles , both in all women ( p > 0.2 ) and in pgdm alone ( p > 0.4 ) . katp was not different between pgdm and con ( 0.06  0.02 1/s vs. 0.07  0.01 1/s ; p = 0.1 ) or between subgroups ( pgdm - ir vs. pgdm - is : 0.06  0.02 1/s vs. 0.06  0.02 1/s ; p = 0.6 ) . fatpase was also comparable between pgdm with and without insulin therapy ( it ) during their pregnancies . 2a ) , but 61% higher in pgdm - ir than in pgdm - is ( p < 0.05 ) . among all women , ir women had 69% higher imcl than is women ( p < 0.007 ; fig . pgdm on it during their pregnancies had higher imcl than those on diet treatment ( dt ) ( it vs. dt : 0.86  0.29% vs. 0.51  0.25% , p = 0.01 ) . ectopic lipids in skeletal muscle ( imcl ; a and c ) and liver ( hcl ; b and d ) of pgdm compared with con ( a and b ) and in ir and is subgroups of the total cohort according to their insulin sensitivity ( ogis ) ( c and d ) . boxes delineate lower and upper quartile , whiskers represent minima and maxima , respectively , medians are indicated by solid line within boxes , and small circles / asterisks represent experimental outliers . imcl : pgdm vs. con ( 0.73  0.32% h2o vs. 0.69  0.5% h2o ; p = 0.08 ns ) hcl : pgdm vs. con ( 3.7  3.5% vs. 1.5  0.9% signal ; p < 0.05 ) imcl : ir vs. is ( 0.90  0.3% h2o vs. 0.54  0.32% h2o ; p < 0.003 ) hcl : ir vs. is ( 4.0  3.3% vs. 2.0  1.8% signal ; p < 0.05 ) . 2b ) . likewise , hcl were twice as high in ir than in is subjects ( p < 0.05 ; fig . 2d ) , but not different among pgdm subgroups . adjusting for bfm diminished these differences . hcl were not different between pgdm with or without it during pregnancy ( dt vs. it : hcl 4.8  5.0% signal vs. 3.1  2.4% signal ) . partial correlation analysis , controlled for bfm , revealed a relationship between fatpase and plasma adiponectin across all women ( p < 0.04 , r = 0.44 ) . fatpase did not relate to measures of insulin sensitivity ( ogis : r = 0.002 , si : r = 0.07 ) or glucose tolerance ( aucgluc : r = 0.005 ) in any subgroup . however , the disposition index related to hcl ( r = 0.59 , p = 0.002 ) and fatpase ( r = 0.37 , p = 0.04 ) in all women . fasting plasma ffa did not relate to fatpase , whereas 2-h postload plasma ffa related to hcl ( r = 0.59 , p = 0.01 ) and insulin sensitivity as assessed from ogis ( r = 0.44 , p = 0.04 ) or si ( r = 0.42 , p = 0.04 ) in pgdm . hcl related to insulin sensitivity ( r = 0.47 , p < 0.02 ) across all women and to imcl ( r = 0.59 , p = 0.05 ) and a1c across ir ( r = 0.64 , p < 0.03 ) . after adjustment for bfm , hcl still related to a1c ( r = 0.57 , p < 0.02 ) in all women . within pgdm , the correlation of hcl with hip circumference ( r = 0.59 , p = 0.04 ) and a1c ( r = 0.62 , p = 0.03 ) remained after adjustment for bfm . we found that myocellular fatpase is lower in pgdm than in con and does not relate to insulin sensitivity or imcl , but correlates positively with plasma adiponectin across all women , suggesting a yet unknown relationship between energy metabolism and adipocyte function . hcl were greater in pgdm , and hcl and postload ffa were negatively related to insulin sensitivity . our pgdm featured slightly greater fat mass , postload glycemia , and insulin resistance than con . except for hdl - cholesterol , they did not differ from con in other variables , including physical activity and resting energy expenditure . this held true even for pgdm - ir , suggesting that this cohort is at lower risk for type 2 diabetes than other mostly obese and glucose - intolerant pgdm , but already exhibits distinct metabolic features . we found moderately lower myocellular fatpase in pgdm compared with con , which was significant only on log - transformation . our cohort was carefully matched to con , except for insulin sensitivity , and probably bears a low risk for rapid progression to diabetes . the observed small differences could also be due to this specific cohort maintaining normal glucose tolerance for up to 4 years postpartum . the difference in fatpase between pgdm and con , however , vanished on correction for bfm and was not found when comparing pgdm - ir with pgdm - is . although one might speculate that the reduction of fatpase resulted from greater body fat content as reported for obese insulin - resistant and overweight type 2 diabetes cohorts ( 17 ) , our data do not allow such a conclusion . basal fatpase , the final step of mitochondrial oxidative phosphorylation , is impaired only in some cohorts presenting with severe insulin resistance and elevated imcl , such as elderly and lean relatives of patients with type 2 diabetes ( 4 ) . the overall higher insulin sensitivity compared with other populations at risk for or having overt type 2 diabetes ( 5,6,18 ) suggests that muscle metabolism was almost normal in our pgdm . the finding that imcl were not different between pgdm and con , but 69% higher in ir than is , underlines the contention that imcl generally correlate with insulin resistance ( 8,19 ) and can be elevated in patients with type 2 diabetes and their insulin - resistant first - degree relatives ( 4 ) . further , the pgdm of our previous study exhibited higher imcl along with greater insulin resistance and bfm ( 8) . of note , baseline fatpase is not necessarily different in patients with overt type 2 diabetes ( 5,6 ) , indicating that mitochondrial dysfunction is not a uniform feature of type 2 diabetes ( 5 ) . the increase in imcl relates to not only diminished mitochondrial capacity for oxidative phosphorylation but also lipid availability . plasma ffa elevation decreases insulin - stimulated fatpase and insulin sensitivity before changes in imcl ( 16 ) . of note , postchallenge plasma ffas were not different between pgdm and con and only slightly higher in ir - pgdm than in is - pgdm . the increase in insulin secretion further argues against mitochondrial dysfunction at the level of the -cell , which has been observed in gdm and some pgdm ( 20 ) . despite the only discrete alterations in muscular metabolism , liver fat content was more than double in all pgdm and even three times more in ir - pgdm compared with that in con , which was still below the detection limits of clinical routine ultrasound . higher hcl have been reported in obese pgdm ( 9 ) and type 2 diabetic patients , in whom hcl tightly correlate with whole - body and hepatic insulin resistance ( 5 ) . steatosis even predicts the development of insulin resistance , type 2 diabetes , and cardiovascular end points ( 1,21 ) . of note , similar to skeletal muscle , impaired mitochondrial function has been recently detected in livers of patients with type 2 diabetes ( 1,22 ) . it has been proposed that primary muscular insulin resistance promotes shifting of ingested carbohydrates away from skeletal muscle to hepatic de novo lipogenesis , thereby increasing hcl independently of obesity ( 18 ) . alternatively , steatosis and/or impaired hepatic mitochondrial function could lead to muscular insulin resistance ( 1,22 ) . we can not address this issue directly , because liver biopsies are not permitted in healthy humans and noninvasive assessment with in vivo p mrs was not available . in pgdm , the 2-h post - glucose load plasma ffa further correlated positively with hcl and negatively with whole - body insulin sensitivity . even after correction for bfm , pgdm and of note , despite the greater bfm , none of the anthropometric parameters reached the cutoff values of the metabolic syndrome . from this it seems that impaired insulin action in these pgdm is primarily located at the level of the liver and already present in the glucose - tolerant state . steatosis may result not only from abnormal fat metabolism but also from disturbed cytokine release . of note , pgdm exhibit higher hcl and lower plasma adiponectin , which is a sensitive predictor for future deterioration of glucose metabolism ( 10 ) . adiponectin has been linked to improved muscular and hepatic insulin sensitivity , which might result from anti - inflammatory and antiatherogenic activity , decreased triglyceride synthesis , and stimulated -oxidation ( 2 ) . adiponectin may also increase muscular mitochondrial number and function , and exert antidiabetic effects ( 23 ) . in support of this contention , the current study showed that plasma adiponectin relates positively to fatpase in all women after adjustment for bfm . moreover , prevention of the development of type 2 diabetes in pgdm by thiazolidinediones ( 24,25 ) could be mediated by increased plasma adiponectin with subsequent reduction of hcl and hepatic and peripheral insulin resistance . in addition , primary abnormal hepatic mitochondrial function could lead to steatosis , because patients with type 2 diabetes have reduced hepatocellular atp levels that correlate with hepatic insulin sensitivity and hcl ( 22 ) . the limitations of the study are the small sample size and the specific selection of pgdm , which restrict the extrapolation of the results to all pgdm . on the other hand , the selected group underwent intensive phenotyping , including tissue - specific metabolic assessment . in summary , glucose - tolerant nonobese pgdm do not show major alterations of muscle glucose and energy metabolism , but already exhibit a subclinical increase of liver fat content suggesting early abnormalities or adaptations of hepatic metabolism .