Muscle mass and functional correlates of insulin sensitivity in lean young Indian men.

BACKGROUND/
OBJECTIVES: There is a high prevalence of diabetes mellitus associated with insulin resistance in Indian adults, probably due to an inappropriately high accumulation of body fat at lower body mass indices (BMIs, kg/m(2)), as well as to a lower skeletal muscle mass. Although skeletal muscle is an important site of glucose disposal, the strength of its association with insulin sensitivity (IS) is unknown in the Indian population. SUBJECTS/
METHODS: This was a cross-sectional study performed to assess the association of body fat, muscle and muscle function with IS in 51 young, healthy, nonobese Indian men with BMI ranging from 15 to 25 kg/m(2), using hyperinsulinemic euglycemic clamp method.
RESULTS: The median IS was 5.32 (mg/(kg min))/(microU/ml), lower, upper quartile, 4.03, 6.56); (SI units: 4.25, lower, upper quartile, 3.22, 5.24 (micromol/(kg min))/(pmol/l)). A multiple linear regression of the natural log transformed value of IS on BMI and body muscle mass measured as the appendicular lean soft tissue (expressed as a percentage of body weight) explained 49% of the variance in IS. Independently, body fat percent and muscle (handgrip) strength showed significant bivariate correlations with IS (rho=-0.61, P<0.001; rho=0.32, P=0.027, respectively), although these variables did not enter into the multiple regression.
CONCLUSIONS: BMI and body fat have been shown to be inversely related to IS at higher BMIs. This study indicates that a relative increase in BMI and reduced muscle mass and possibly function are also associated with reduced IS in lean Indian men.