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Muscle fiber composition and capillary density in women and men with NIDDM
P Mårin1, B Andersson, M Krotkiewski
1Department of Medicine, Sahlgren's Hospital, University of Göteborg, Sweden.
Objective:
To determine whether muscle fiber composition and capillary density differed between diabetic and nondiabetic subjects.
Research Design And Methods:
Muscle fiber composition and capillary density were determined in biopsies from women and men with non-insulin-dependent diabetes mellitus (NIDDM) and compared with those of control subjects matched for gender, age, obesity, and the waist-to-hip ratio, which are all factors known to influence muscle morphology.
Results:
Patients with NIDDM, as well as control subjects with abdominal obesity and insulin resistance, showed the same abnormalities in muscle morphology, namely, a low percentage of type I fibers, elevated type II (particularly type IIB) fibers, and a low capillary density. These changes correlated closely with insulin concentrations in both diabetic and nondiabetic groups.
Conclusions:
Recent information suggests that insulin may regulate myosin synthesis in muscle in the direction of the changes observed. Therefore, it is possible that muscle fiber composition abnormalities in insulin-resistant conditions are secondary to hyperinsulinemia. However, the low capillary density, hypothetically, may contribute to insulin resistance.