mr imaging and mr spectroscopy were performed twice in 10 c - peptide  negative , nonsmoking patients with type 1 diabetes ( five male ) using insulin treatment by insulin pump therapy ( continuous subcutaneous insulin infusion ) .
one study was done after a 3-day period in which subjects aimed at optimal blood glucose levels measured by a continuous glucose monitoring system ( medtronic ) .
the second study was performed after 50% reduction in basal and bolus insulin infusions during 24 h , compared with the first study , in order to maintain hyperglycemia with glucose levels between 15 and 20 mmol / l . for both occasions , patients were instructed to maintain the same caloric intake for 3 days before examination .
the sequence between the euglycemic and hyperglycemic occasions was randomly assigned . before mr examination , blood samples ( postprandial ) were taken .
mr spectroscopy measurements ( 1.5-t ; philips ) were obtained using a point - resolved , spatially localized spectroscopic pulse sequence to acquire single voxel ( 8 ml ) spectra . for the heart ,
lipid resonances of myocardial and hepatic tg were summed and calculated as a percentage of the unsuppressed water signal ( [ tg / water ]  100 ) .
to assess left ventricular ( lv ) systolic function , the heart was imaged in the short axis orientation . to assess lv diastolic function , a phase contrast sequence with velocity encoding
analysis was performed using mass and flow ( medis ) to quantify lv ejection fraction and flow velocities in early diastole ( early filling phase [ e ] ) and at atrial contraction ( atrial filling phase [ a ] , e / a ratio , and e deceleration ) .
patient characteristics at baseline and during hyperglycemia are shown in table 1 . during partial insulin deprivation , hyperglycemic dysregulation was present in all patients ( mean plasma 24-h glucose was 8.4  0.6
mmol / l during the control study , which increased to 15.9  0.8 mmol / l during partial insulin deprivation [ p < 0.001 ] ) and associated with an increase in plasma levels of nonesterified fatty acids from 0.31  0.05 to 0.46  0.07 mmol / l ( p = 0.015 ) .
myocardial tg content was 0.31  0.04% at baseline and did not change during hyperglycemic dysregulation ( 0.34  0.06% ; p = 0.587 ) .
e / a ratio was unaffected ( 1.9  0.2 at baseline vs. 1.9  0.3 ) .
this is the first study to document the effects of short - term hyperglycemic dysregulation on myocardial tg content and lv function in patients with type 1 diabetes .
the present study shows that hyperglycemic dysregulation for 24 h , as frequently observed in patients with type 1 diabetes , does not modulate myocardial tg content or myocardial function , despite considerable metabolic dysregulation .
we hypothesized that short - term partial insulin deprivation results in changes in myocardial tg content , possibly associated with changes in myocardial function .
stiffness of intermediate - sized arteries is rapidly increased in patients with type 1 diabetes during hyperglycemia , whereas larger arteries seem unaffected ( 5 ) .
moreover , in healthy subjects myocardial function and tg content rapidly adapt to changes in metabolic state ( 2 ) .
interestingly , this adaptation could not be evoked by short - term hyperglycemic dysregulation , suggesting that the heart is protected from these short - term effects .
nonetheless , we can not exclude the possibility that prolongation of the duration of partial insulin deprivation might have resulted in changes in myocardial function and tg content .
myocardial fatty acid utilization is increased , whereas myocardial glucose uptake is considerably lower in diabetic patients compared with that in control subjects ( 6 ) .
accordingly , the present study interestingly shows that myocardial tg content in diabetic patients was not different from the values we observed in studies in healthy subjects ( 2,3 ) .
however , fatty acid kinetics during hyperglycemia can not be derived from the present data , and we can not exclude changes in myocardial fatty acid oxidation .
hepatic tg content was measured to study the effects of insulin deprivation on tissue - specific tg distribution because we previously found discrepant effects of interventions on heart and liver ( 2 ) .
however , in the present study design insulin deprivation did not result in altered hepatic tg content . in conclusion , short - term partial insulin deprivation resulting in hyperglycemic dysregulation , which is frequently observed in patients with type 1 diabetes , does not modulate myocardial or hepatic tg content or lv function , despite considerable metabolic dysregulation .
 objective  to evaluate the effects of hyperglycemia due to partial insulin deprivation on myocardial triglyceride ( tg ) content and myocardial function in patients with type 1 diabetes.research design and methods  myocardial and hepatic tg content and left ventricular ( lv ) function were measured by magnetic resonance ( mr ) spectroscopy and mr imaging during optimal glucoregulation and after 24 h of partial insulin deprivation ( n = 10).results  mean insulin infusion rate was 45  5 units at baseline , whereas it was 27  5 units during hyperglycemia ( per 24 h , p < 0.001 ) . 
 plasma glucose levels increased from 8.4  0.6 to 15.9  0.8 mmol / l ( p < 0.001 ) , and plasma levels of nonesterified fatty acids from 0.31  0.05 to 0.46  0.07 mmol / l ( p = 0.015 ) . 
 hyperglycemia had no effects on myocardial or hepatic tg content and lv function.conclusionsshort-term hyperglycemic dysregulation does not modulate myocardial or hepatic tg content or myocardial function , despite considerable metabolic adaptations . 
RESEARCH DESIGN AND METHODS
RESULTS
CONCLUSIONS