Endocrine Abstracts

Oral combined hormonal contraceptives (CHCs) have been suggested to induce more unbeneficial metabolic effects than vaginal CHCs. CHCs are used routinely to treat the clinical symptoms of polycystic ovary syndrome (PCOS), but there are no studies investigating whether the vaginal route is safer in women with known metabolic risks.

Twenty-five women with PCOS defined according to the Rotterdam criteria were randomized to use either oral contraceptive pills (desogestrel-ethinylestradiol) (n=14) or contraceptive vaginal rings (etonogestrel-ethinylestradiol) (n=11) continuously for 9 weeks. Blood samples were drawn and OGTT performed at baseline and at 9 weeks.

Serum levels of SHBG increased and consequently the free androgen index (FAI) decreased in both study groups from baseline to 9 weeks of treatment [oral: 3.2 (95% confidence interval, CI: 2.2; 4.3) to 0.7 (0.5; 1.0); vaginal: 3.8 (1.8; 5.8) to 0.6 (0.5; 0.8), P≤0.003 in both groups]. Insulin sensitivity was reduced at 9 weeks according to the Matsuda index [oral: 2.5 (0.1; 4.8) to 0.2 (0.2; 0.3), P=0.035]; vaginal: 3.0 (0.4; 4.4) to 0.2 (0.1; 0.2), P=0.366]. Serum levels of triglycerides [oral 0.9 (0.7; 1.2) to 1.3 (0.8; 1.8) mmol/l, P=0.132; vaginal 0.8 (0.6; 1.0) to 1.3 (0.9; 1.7) mmol/l, P=0.003] hs-CRP (P=0.034) and the AUCglucose during the OGTT (P=0.017) rose significantly only in the vaginal group. The AUCinsulin (oral: P=0.36, vaginal: P=0.16) increased non-significantly from baseline to 9 weeks in both treatment groups. There were no differences in serum levels of glucose, insulin, hs-CRP, lipids or testosterone between the treatment groups at baseline or after 9 weeks.

Against our hypothesis, vaginal CHCs were not metabolically safer than oral CHCs. These results emphasize the importance of monitoring glucose metabolism during CHC use regardless of the route of administration, especially in PCOS women displaying typically risks of type 2 diabetes or cardiovascular diseases.