Three-month treatment with metformin or dexfenfluramine does not modify the effects of diet on anthropometric and endocrine-metabolic parameters in abdominal obesity

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Abstract
Abdominal obesity is connoted by hyperinsulinism and insulin insensitivity, a trend toward glucose intolerance, hypoactivity of GH/IGF-I axis and alterations of hypothalamo-pituitary-adrenal (HPA) axis. It has been hypothesized that treatment with metformin (MET) and dexfenfluramine (DEX) could counteract those endocrine- metabolic alterations. Thus, we studied the effects of 3-month treatment with MET or DEX on anthropometric (BMI, WHR, FM and FFM), metabolic (basal and OGTT-induced glucose) and hormonal variables (IGF-I, DHEA-S, androstendione, testosterone, fT3, fT4, TSH, basal and OGTT-induced insulin) as well as on blood pressure in 28 normotensive patients with abdominal obesity (OB, 3 M, 25 F; 47.5±1.5 yr [mean±SE], BMI 35.4±1.1 kg/m2, WHR 0.98±0.04 and 0.86±0.07, in M and F, respectively). All patients were on balanced hypocaloric diet (1400 Kcal/day). Patients were randomly assigned to treatment with MET (no.=10, 500 mg twice daily po) or DEX (no.=10, 15 mg thrice daily po) or placebo (no.=8). Before treatment all groups had similar anthropometric, metabolic and hormonal values. After 3-month treatment with MET, DEX or placebo, weight, BMI and WHR reductions were similar in all groups (pvs baseline in either group). In each group FFM/FM ratio showed non significant trend toward increase. No significant variations in metabolic and endocrine variables were recorded in each group after 1 and 3-month treatment. However, glucose tolerance, OGTT-induced insulin response, glucose/ insulin ratio showed a similar trend toward improvement in all groups, while IGF-I, 24 h urinary cortisol, DHEA-S, androstendione, testosterone, thyroid hormone and TSH levels did not show any variation. Significant (p<0.02) and similar reductions of DBP, but not of SBP, levels were found in all groups. In conclusion, our findings demonstrate that, at least after 3-month treatment, metformin and dexfenfluramine do not modify the effects of diet on anthropometric, metabolic and hormonal parameters as well as on blood pressure in patients with abdominal obesity.