Association of intramyocellular, intraperitoneal and liver fat with glucose tolerance in severely obese adolescents.
OBJECTIVE
Impaired glucose tolerance (IGT) is common among obese adolescents. The aim of the present study was to investigate the association between glucose tolerance and intramyocellular, intra-abdominal and liver fat in adolescents presenting with early-onset severe obesity.


METHODS
We studied 21 adolescents (mean age 13.5 years, range 11.5-15.9 years) referred to secondary care due to severe obesity (relative weight for height > +60% or body mass index > 98th percentile for age and sex, before the age of 10 years) and their eight non-obese siblings (mean age 14.4 years, range 11.8-16.7 years). All subjects underwent oral glucose tolerance tests, followed by magnetic resonance spectroscopy (MRS) to measure the intramyocellular fat content in mainly oxidative soleus and mainly glycolytic tibialis anterior muscles. MRS was also used to measure liver fat. Abdominal fat (subcutaneous, intraperitoneal and retroperitoneal) was measured using MR imaging.


RESULTS
Compared with their non-obese siblings, the obese adolescents had increased fat deposition in all anatomic locations studied. Eight obese adolescents had IGT, and they also had increased intramyocellular fat in the soleus (P=0.03) and increased intraperitoneal fat (P=0.04) compared with obese subjects with normal glucose tolerance (NGT). In contrast, no significant difference was seen between obese adolescents with NGT and IGT in liver fat (P=0.9) or intramyocellular fat in the tibialis anterior (P=0.13). In logistic regression analysis, increased soleus intramyocellular fat and intraperitoneal fat were significant predictors of IGT.


CONCLUSIONS
IGT in obese adolescents is associated with increased intramyocellular and intraperitoneal fat rather than liver fat.
Saukkonen
Tero
T
Hospital for Children and Adolescents, University of Helsinki, 00029 Helsinki, Finland. tskk@novonordisk.com
Heikkinen
Sami
S
Hakkarainen
Antti
A
Häkkinen
Anna-Maija
AM
van Leemput
Koen
K
Lipsanen-Nyman
Marita
M
Lundbom
Nina
N
D050153:Abdominal Fat / Q000378:metabolism*; D000293:Adolescent; D000367:Age Factors; D001823:Body Composition / Q000502:physiology; D002648:Child; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000097:blood* / Q000150:complications / Q000175:diagnosis; D005260:Female; D018149:Glucose Intolerance / Q000097:blood* / Q000150:complications; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism*; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000175:diagnosis