Insulin resistance and body fat distribution in South Asian men compared to Caucasian men.
OBJECTIVE
South Asians are susceptible to insulin resistance even without obesity. We examined the characteristics of body fat content, distribution and function in South Asian men and their relationships to insulin resistance compared to Caucasians.


METHODS
Twenty-nine South Asian and 18 Caucasian non-diabetic men (age 27+/-3 and 27+/-3 years, respectively) underwent euglycemic-hyperinsulinemic clamp for insulin sensitivity, underwater weighing for total body fat, MRI of entire abdomen for intraperitoneal (IP) and subcutaneous abdominal (SA) fat and biopsy of SA fat for adipocyte size.


RESULTS
Compared to Caucasians, in spite of similar BMI, South Asians had higher total body fat (22+/-6 and 15+/-4% of body weight; p-value<0.0001), higher SA fat (3.5+/-1.9 and 2.2+/-1.3 kg, respectively; p-value = 0.004), but no differences in IP fat (1.0+/-0.5 and 1.0+/-0.7 kg, respectively; p-value = 0.4). SA adipocyte cell size was significantly higher in South Asians (3491+/-1393 and 1648+/-864 microm2; p-value = 0.0001) and was inversely correlated with both glucose disposal rate (r-value = -0.57; p-value = 0.0008) and plasma adiponectin concentrations (r-value = -0.71; p-value<0.0001). Adipocyte size differences persisted even when SA was matched between South Asians and Caucasians.


CONCLUSIONS
Insulin resistance in young South Asian men can be observed even without increase in IP fat mass and is related to large SA adipocytes size. Hence ethnic excess in insulin resistance in South Asians appears to be related more to excess truncal fat and dysfunctional adipose tissue than to excess visceral fat.
Chandalia
Manisha
M
Departments of Internal Medicine, Endocrinology and Metabolism, Center for Human Nutrition, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America. Manisha.chandalia@utsouthwestern.edu
Lin
Ping
P
Seenivasan
Thanalakshmi
T
Livingston
Edward H
EH
Snell
Peter G
PG
Grundy
Scott M
SM
Abate
Nicola
N
D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D044466:Asian People; D050218:Body Fat Distribution; D005947:Glucose / Q000378:metabolism; D015309:Glucose Clamp Technique; D006801:Humans; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat / Q000378:metabolism; D008297:Male; D044465:White People
D005947:Glucose