First, to describe the methodology and issues related to setting up a hyperinsulinaemic euglycaemic clamp (HEC) technique and to use this method to compare the IS of young adult male low BMI (LBMI) subjects (BMI < 18.5 kg/[m.sup.2]) with age and gender matched normal weight (NW) subjects (BMI between 18.5 and < 25 kg/ [m.sup.2]).
Subjects: Ten young resident south Indian male NW and ten LBMI (aged 19-32 yr) subjects participated in this study conducted from March 2006 to February 2007.
NW subjects had a % BF ranging from 13.6 to 25.1 per cent and LBMI from 5.4 to 12.7 per cent.
The fasting plasma basal glucose ranged from 82.9 to 108.8, and 87.0 to 107.5 (mg/dl) in NW and LBMI subjects respectively.
Our study demonstrated that healthy NW Indians had a reduced Clamp IS, when compared with LBMI Indians, who conceivably represent that portion of the population least affected by the nutrition and epidemiological transition that is associated with increased diabetes.
The high degree of correlation between Clamp IS and % BF as well as the differences in Clamp IS between NW and LBMI groups suggests that the relation between BMI and IS is likely to be a continuum with no specific cut-off for BMI beyond which the IS suddenly decreases.
The group with the highest exposure (> 60 dB) had statistically significant larger mean waist circumference, mean BMI, and mean LBMI in all models.
For LBMI, we found a significant effect modification by age (p = 0.018), with higher estimates for the association between road traffic noise and LBMI among participants < 56 years of age (0.10; 95% CI: 0.075, 0.13) compared with older participants (0.016; 95% CI: 0.033, 0.089) (Table 4).
In this large cross-sectional study of middle-aged Danish men and women, we found consistent and statistically significant positive associations between road traffic noise and waist circumference, BMI, BFMI, and LBMI. Road traffic noise was also associated with a higher prevalence of being overweight and obese.
We observe a positive association for LBMI. This is to be expected because the metabolically active lean body mass (LBM) increases with increasing body fat mass (BFM) (VanItallie et al.
The results indicated that the association between road traffic noise and LBMI was weaker among those above the median age (56.2 years) compared with younger participants.
We also found nonlinear positive association between railway noise and BMI, waist circumference, and LBMI for railway noise exposure > 60 dB.