Relationship of liver enzymes to insulin sensitivity and intra-abdominal fat.
OBJECTIVE
The purpose of this study was to determine the relationship between plasma liver enzyme concentrations, insulin sensitivity, and intra-abdominal fat (IAF) distribution.


METHODS
Plasma gamma-glutamyl transferase (GGT), aspartate transaminase (AST), alanine transaminase (ALT) levels, insulin sensitivity (insulin sensitivity index [S(I)]), IAF area, and subcutaneous fat (SCF) area were measured in 177 nondiabetic subjects (75 men and 102 women, aged 31-75 years) with no history of liver disease. On the basis of BMI (< or > or = 27.5 kg/m2) and S(I) (< or > or = 7.0 x 10(-5) min/pmol) subjects were divided into lean insulin sensitive (LIS, n = 53), lean insulin resistant (LIR, n = 60), and obese insulin resistant (OIR, n = 56) groups.


RESULTS
Levels of all three liver enzymes were higher in men than in women (P < 0.0001 for each). In men, GGT levels were higher in insulin-resistant than in insulin-sensitive subjects (P < 0.01). In women, GGT levels were higher in the OIR than in the LIS group (P < 0.01) but no different in the LIR group. There was no difference in ALT and AST levels among the LIS, LIR, and OIR groups. GGT was associated with S(I) (r = -0.26, P < 0.0001), IAF area (r = 0.22, P < 0.01), waist-to-hip ratio (WHR) (r = 0.25, P = 0.001), BMI (r = 0.17, P < 0.05), and SCF area (r = 0.16, P < 0.05) after adjustments for age and sex. In men, only S(I) (r = -0.29, P < 0.05) remained independently correlated with GGT in multiple regression analysis. In women, IAF area (r = 0.29, P < 0.01) and WHR (r = 0.29, P < 0.01) were independently associated with GGT, but S(I) was not.


CONCLUSIONS
In nondiabetic men GGT but not AST or ALT levels, are inversely related to insulin sensitivity independent of IAF area. However in women, GGT is related to measures of central body fat rather than to insulin sensitivity.
Department of Medicine, VA Puget Sound Health Care System, and University of Washington, Seattle, WA 98108, USA.
Tara M
TM
Wallace
Kristina M
KM
Utzschneider
Jenny
J
Tong
Darcy B
DB
Carr
Sakeneh
S
Zraika
Daniel D
DD
Bankson
Robert H
RH
Knopp
Steven E
SE
Kahn
D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood*; D001219:Aspartate Aminotransferases / Q000097:blood*; D005260:Female; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000201:enzymology*; D012016:Reference Values; D005723:gamma-Glutamyltransferase / Q000097:blood*
D007328:Insulin; D005723:gamma-Glutamyltransferase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase