A range of hormones which regulate energy metabolism are secreted by adipose tissue, among which adiponectin and leptin are the main adipokines regulating insulin sensitivity.
The aim of our study was to estimate and compare levels of adiponectin, leptin, C-peptide and adiponectin-to-leptin ratio (A/L) in obese non-diabetic, Type 1 diabetic (T1D) children and lean non-diabetic controls.
BMI and SDS BMI were calculated in 88 children (46f, 42m, age 14.8±3.6 yrs): 32 pts with obesity, 34 pts with T1D, 22 lean non-diabetic persons. Serum levels of C-peptide, adiponectin and leptin were measured by ELISA.
Median adiponectin levels were higher in control group (22.1 mcg/ml; P=0.0001) and T1D pts (21.1 mcg/ml; P=0.0002) as compared with obese pts (12.6 mcg/ml). Leptin levels were higher in pts with obesity (41.2 ng/ml) as compared with control (1.8 ng/ml; P<0.000001) and T1D pts (2.8 mcg/ml; P<0.000001). Leptin levels in T1D pts were higher than in control group (P=0.027), while adiponectin levels were practically the same.
Highest A/L ratio was in lean controls (11.6), lowest in obese non-diabetic children (0.5), whereas in T1D pts A/L ratio was 6.6. Differences between groups were significant (P<0.05).
We did not find significant correlation of adiponectin and leptin levels, adiponectin-to-leptin ratio with age at observation, BMI, C-peptide. At the same time adiponectin level and adiponectin-to-leptin ratio negatively correlate with BMI in T1D (r=−0.37, P=0.032; r=−0.35, P=0.049) and obese non-diabetic children (r=−0.55, P=0.001; r=0.45, P=0.011).
Surprisingly, in obese non-diabetic pts we find significant correlation of adiponectin and age at observation (r=−0.59, P=0.0004).
We concluded that the older obese pts are, the lower adiponectin level is. Adiponectin-to-leptin ratio is a more useful marker of impaired adipokines secretion than adiponectin or leptin levels alone, though further study is necessary to prove reliability of this test for assessment of insulin sensitivity.