Correlation of insulin sensitivity with bone mineral status in obese adolescents with nonalcoholic fatty liver disease.

Aim: The aim of this study was to investigate the relationships between bone mineral density (BMD) vs insulin resistance and metabolic risk factors in obese adolescents with nonalcoholic fatty liver disease (NAFLD).
Patients and Methods: Eighty-two obese adolescents [45 girls and 37 boys, mean age: 12·3 ± 1·7 years, mean body mass index-standard deviation score (BMI-SDS): 1·9 ± 0·2] and 30 control subjects (15 girls and 15 boys, mean age: 12·3 ± 1·45 years, mean BMI-SDS: 0·5 ± 0·7) were enrolled the study. The obese subjects were divided into two groups based on the presence or absence of liver steatosis with high transaminases (NAFLD group and non-NAFLD group). Insulin resistance was evaluated by homeostasis model assessment (HOMA-IR) from fasting samples. BMD was determined by dual-energy X-ray absorptiometry.
Results: Fasting insulin levels in the NAFLD group were significantly higher than in the non-NAFLD obese (32·3 ± 24·0 vs 11·02 ± 2·95 mU/l, P < 0·001) and control groups (8·4 ± 2·4 mU/l, P< 0·001). The NAFLD group had higher values of HOMA-IR than the non-NAFLD obese (7·3 ± 0·1 vs 2·3 ± 0·7, P < 0·001) and control groups (1·8 ± 0·5, P < 0·001). BMD-SDS measurements were lower in the NAFLD group than in the non-NAFLD (0·56 ± 0·3 vs 1·02 ± 0·9, P < 0·001) and control groups (0·56 ± 0·3 vs 1·37 ± 1·04, P < 0·001). BMD-SDS was positively correlated with BMI-SDS (r = 0·530, P = 0·004) and negatively correlated with HOMA-IR (r = -0·628, P = 0·017) in the NAFLD obese group.
Conclusion: This study reports the association between BMD-SDS and insulin resistance in obese adolescents both with and without NAFLD, although the NAFLD group had a lower BMD-SDS than the non-NAFLD group. We suggest that NAFLD has a detrimental effect on bone health in adolescents, and it is correlated with increased insulin resistance.
(© 2011 Blackwell Publishing Ltd.)