title: Mitochondrial capacity is affected by glycemic status in young untrained women with type 1 diabetes but is not impaired relative to healthy untrained women.
abstract: In this study, we examined whether glycemic status influences aerobic function in women with type 1 diabetes and whether aerobic function is reduced relative to healthy women. To this end, we compared several factors determining aerobic function of 29 young sedentary asymptomatic women (CON) with 9 women of similar age and activity level with type 1 diabetes [DIA, HbA1c range = 6.9-8.2%]. Calf muscle mitochondrial capacity was estimated by (31)P-magnetic resonance spectroscopy. Capillarization and muscle fiber oxidative enzyme activity were assessed from vastus lateralis and soleus muscle biopsies. Oxygen uptake and cardiac output were evaluated by ergospirometry and N(2)O/SF(6) rebreathing. Calf muscle mitochondrial capacity was not different between CON and DIA, as indicated by the identical calculated maximal rates of oxidative ATP synthesis [0.0307 (0.0070) vs. 0.0309 (0.0058) s(-1), P = 0.930]. Notably, HbA1c was negatively correlated with mitochondrial capacity in DIA (R(2) = 0.475, P = 0.040). Although HbA1c was negatively correlated with cardiac output (R(2) = 0.742, P = 0.013) in DIA, there was no difference between CON and DIA in maximal oxygen consumption [2.17 (0.34) vs. 2.21 (0.32) l/min, P = 0.764], cardiac output [12.1 (1.9) vs. 12.3 (1.8) l/min, P = 0.783], and endurance capacity [532 (212) vs. 471 (119) s, P = 0.475]. There was also no difference between the two groups either in the oxidative enzyme activity or capillary-to-fiber ratio. We conclude that mitochondrial capacity depends on HbA1c in untrained women with type 1 diabetes but is not reduced relative to untrained healthy women.
authors.affiliation: ETH Zurich, Exercise Physiology, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Flurin
authors.initials: F
authors.lastname: Item
authors.forename: Susanne
authors.initials: S
authors.lastname: Heinzer-Schweizer
authors.forename: Michael
authors.initials: M
authors.lastname: Wyss
authors.forename: Piero
authors.initials: P
authors.lastname: Fontana
authors.forename: Roger
authors.initials: R
authors.lastname: Lehmann
authors.forename: Anke
authors.initials: A
authors.lastname: Henning
authors.forename: Markus
authors.initials: M
authors.lastname: Weber
authors.forename: Peter
authors.initials: P
authors.lastname: Boesiger
authors.forename: Urs
authors.initials: U
authors.lastname: Boutellier
authors.forename: Marco
authors.initials: M
authors.lastname: Toigo
mesh_terms: D000328:Adult; D001706:Biopsy; D001786:Blood Glucose / Q000378:metabolism*; D002302:Cardiac Output / Q000502:physiology; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism* / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008931:Mitochondria, Muscle / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D010100:Oxygen