Anorexia nervosa (AN) is an eating disorder, resulting in sustained low weight. In AN, similarly to syndromes of lipodystrophy, one observes the significant loss of the adipose tissue. In lipodystrophies, despite the lack of subcutaneous adipose tissue, insulin resistance is observed. Adipose tissue is known as a source of a variety of bioactive peptides, known as adipocytokines. The aim of the present study was to examine the plasma concentration of adipocytokines in relation to insulin sensitivity in women with AN.
The study group consisted of 16 women with AN, 16 women with obesity and 18 healthy normal weight female controls. The oral glucose tolerance test and euglycemic hyperinsulinemic clamp were performed in all the patients. The plasma concentrations of adiponectin, TNF-α, soluble TNF-α receptors (sTNFR1, sTNFR2) and IL-6, soluble form of IL-6 receptor (sIL-6R) were estimated.
Insulin sensitivity index (M) was not different in AN and healthy controls, but was significantly increased in AN in comparison to obese women (P=0.002). Adiponectin plasma levels were significantly higher in AN than control subjects and obese women (P=0.01, P=0.003, respectively). There were no differences in plasma concentrations of TNF-α, sTNFR1, sTNFR2, IL-6, sIL-6R among groups, however plasma free fatty acids (FFA) were significantly lower in AN than control subjects and obese women (P=0.00003, P=0.00001, respectively). Adiponectin levels were negatively correlated with BMI (r=−0.40, P=0,005) and waist girth (r=−0.44, P=0.002). Fasting FFA concentrations were related negatively to insulin sensitivity (r=−0.55, P=0.00007) and to adiponectin concentrations (r=−0.34, P=0.026).
Our data show that lack of adipose tissue observed in anorectic patients has no influence on insulin sensitivity, probably due to low plasma FFA concentration. It points out that in AN the adipocytes are still capable of functioning at the level that is sufficient to prevent the metabolic consequences.