Treatment of endometriosis with Implanon versus GnRH agonists: effect on
insulin sensitivity
A. Cagnacci, A. Tirelli, M. Cannoletta, D. Pirillo, S. Malmusi, D.
Radi, A. Volpe
Department of Obstetrics Gynaecology and Paediatrics, University of Modena,
Italy
Objectives: Medical therapy is usually performed after surgical
laparoscopic treatment for moderate-to-severe endometriosis. GnRH agonists, are
usually administered for the short-term, and oral contraceptives for the
long-term treatment of endometriosis. Oral contraceptives may induce metabolic
modifications among which a reduction of insulin sensitivity (SI). Beside the
progestin, the estrogenic component of the oral contraceptive may impair SI. In
this study we wanted to evaluate the effect of a progestin only administration
on SI of women with endometriosis, in comparison to GnRH analog-treatment.
Design & Methods: The study was performed in 26 women with
endometriosis that after laparoscopic surgery were randomised to receive a GnRH
analogue at the dose 3.75/28 days for 6 cycles (leuprorelin; Enantone, Takeda)
or a subcutaneous single rod progestin implant (etonogestrel; Implanon, Akzo
Nobel). In each woman SI was evaluated prior to treatment in the early
follicular phase of the first menstrual cycle and after 5 months of treatment.
SI or insulin-independent glucose utilisation (Sg) was investigated by the
minimal model method applied to a frequently sampled i.v. glucose tolerance
test.
Results: SI was not significantly modified by the GnRH-analog
(5.29+1.29 vs. 3.99+0.8) and was significantly decreased by the progestin
implant (5.73+1.12 vs. 3.95+0.77; p50.05). Sg, fasting glucose, insulin,
C-peptide and C-peptide/insulin were not modified by either treatment.
Conclusions: As previously reported for oral contraceptives, the
administration of a progestin only contraceptive by subcutaneous implant is
associated with a slight deterioration of SI, with no modification of fasting
glucose control.
