Effect on insulin sensitivity of Implanon vs. GnRH agonist in women with endometriosis

OBJECTIVES: To evaluate the influence of two medical treatments for endometriosis on insulin sensitivity. STUDY DESIGN: After surgery, 26 women with endometriosis were randomly allocated to a 6-month treatment with a GnRH agonist (Leuprorelin 3.75 mg/28 days) or a subdermal progestin implant (etonogestrel 68 mg). Insulin sensitivity (SI) and glucose utilization independent of insulin (Sg) were investigated at baseline and after 6 months by a frequently sampled intravenous glucose tolerance test (FSIGT) associated with the minimal model method. RESULTS: Both therapies tended to decrease SI, but the effect did not reach statistical significance in the GnRH agonist group (5.43+/-1.29 vs. 3.99+/-0.8) and was significant in the etonogestrel group (5.74+/-1.12 vs. 3.95+/-0,78; p=.046). Sg, fasting glucose, insulin, C-peptide and C-peptide/insulin were not modified by either treatment. CONCLUSIONS: The modifications of glucose-insulin metabolism induced by the GnRH agonist are of no relevance for the short-term use of this molecule. Even if the modification induced by the etonogestrel implant is subtle and of no major impact, it should be taken into consideration for the long-term treatment of individuals with abnormalities of glucose-insulin metabolism.