title: Skeletal muscle mitochondrial capacity and insulin resistance in type 2 diabetes.
abstract: OBJECTIVE
  The objective of this study was to determine the role of maximum mitochondrial capacity on the variation in insulin sensitivity within a population of patients with type 2 diabetes mellitus (T2DM).
  
  
  METHODS
  Fifty-eight participants enrolled in a cross-sectional design: eight active controls [maximum aerobic capacity (VO(2max)) > 40 ml/kg · min], 17 healthy sedentary controls without a family history (FH-) and seven with a family history (FH+) of diabetes, four obese participants, and 21 patients with T2DM. Mitochondrial capacity was measured noninvasively using (31)P magnetic resonance spectroscopy of the vastus lateralis. Maximal ATP synthetic rate (ATP(max)) was determined from the rate of phosphocreatine (PCr) recovery after short-term isometric exercise.
  
  
  RESULTS
  ATP(max) was lower (P < 0.001) in T2DM and higher (P < 0.001) in active as compared with healthy sedentary FH- (active, 1.01 ± 0.2; FH-, 0.7 ± 0.2; FH+, 0.6 ± 0.1; obese, 0.6 ± 0.1; T2DM, 0.5 ± 0.2 mm ATP/sec; ANOVA P < 0.0001). Insulin sensitivity, measured by euglycemic-hyperinsulinemic (80 mIU/m(2) · min) clamp was also reduced in T2DM (P < 0.001) (active, 12.0 ± 3.2; FH-, 7.8 ± 2.2; FH+, 6.8 ± 3.5; obese, 3.1 ± 1.0; T2DM, 3.4 ± 1.6; mg/kg estimated metabolic body size · min; ANOVA P < 0.0001). Unexpectedly, there was a broad range of ATP(max) within the T2DM population where 52% of subjects with T2DM had ATP(max) values that were within the range observed in healthy sedentary controls. In addition, 24% of the T2DM subjects overlapped with the active control group (range, 0.65-1.27 mm ATP/sec). In contrast to the positive correlation between ATP(max) and M-value in the whole population (r(2) = 0.35; P < 0.0001), there was no correlation between ATP(max) and M-value in the patients with T2DM (r(2) = 0.004; P = 0.79).
  
  
  CONCLUSIONS
  Mitochondrial capacity is not associated with insulin action in T2DM.
authors.affiliation: Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge,Louisiana 70808, USA.
authors.forename: Sudip
authors.initials: S
authors.lastname: Bajpeyi
authors.forename: Magdalena
authors.initials: M
authors.lastname: Pasarica
authors.forename: Cedric
authors.initials: C
authors.lastname: Moro
authors.forename: Kevin
authors.initials: K
authors.lastname: Conley
authors.forename: Sharon
authors.initials: S
authors.lastname: Jubrias
authors.forename: Olga
authors.initials: O
authors.lastname: Sereda
authors.forename: David H
authors.initials: DH
authors.lastname: Burk
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Zhang
authors.forename: Alok
authors.initials: A
authors.lastname: Gupta
authors.forename: Lise
authors.initials: L
authors.lastname: Kjems
authors.forename: Steven R
authors.initials: SR
authors.lastname: Smith
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D005080:Exercise Test; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009043:Motor Activity / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009765:Obesity / Q000150:complications / Q000378:metabolism / Q000473:pathology; D057185:Sedentary Behavior; D054928:Validation Studies as Topic; D055815:Young Adult