Skeletal muscle fiber composition is related to adiposity and in vitro glucose transport rate in humans.
The purpose of this study was to determine if a relationship exists among skeletal muscle fiber composition, adiposity, and in vitro muscle glucose transport rate in humans. Rectus abdominus muscle was obtained during elective abdominal surgery from nonobese control (n = 12), obese (n = 12), and obese non-insulin-dependent diabetes mellitus (NIDDM) patients (n = 10). The obese NIDDM group had a significantly lower percentage of type I muscle fibers (32.2 +/- 1.9%) than the obese group (40.4 +/- 2.7%), and both obese groups were significantly lower than the control group (50.0 +/- 2.6%). Insulin-stimulated glucose transport, determined on 28 subjects, was significantly lower in both the obese (3.83 +/- 0.48 nmol.min-1.mg-1) and NIDDM (3.93 +/- 1.0 nmol.min-1.mg-1) groups vs. the control group (7.35 +/- 1.50 nmol.min-1.mg-1). Body mass index (BMI) was inversely correlated to percent type I fibers (r = -0.50, P < 0.01) and to the insulin-stimulated glucose transport rate (r = -0.53, P < 0.01). The percentage of type I muscle fibers was related to the insulin-stimulated glucose transport rate (r = 0.57, P < 0.01), although this relationship was not significant after adjusting for BMI. Although these data do not support an independent relationship between fiber type and insulin action in obesity, a reduced skeletal muscle type I fiber population may be one component of a multifactorial process involved in the development of insulin resistance.
Hickey
M S
MS
Human Performance Laboratory, School of Health and Human Performance, East Carolina University, Greenville, North Carolina 27858.
Carey
J O
JO
Azevedo
J L
JL
Houmard
J A
JA
Pories
W J
WJ
Israel
R G
RG
Dohm
G L
GL
D000273:Adipose Tissue; D001692:Biological Transport / Q000187:drug effects; D001823:Body Composition; D015992:Body Mass Index; D003920:Diabetes Mellitus / Q000378:metabolism / Q000473:pathology; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000473:pathology; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology*; D009765:Obesity / Q000378:metabolism / Q000473:pathology
D007328:Insulin; D005947:Glucose