Objective: To compare the effects of two progestogen-only pills, containing either desogestrel or levonorgestrel, on carbohydrate metabolism, and adrenal and thyroid function.
Methods: In a double-blind, randomized, multicenter study in Finland, 84 healthy female volunteers received either desogestrel 75 microg/day or levonorgestrel 30 microg/day for seven treatment periods of 28 days. The following laboratory parameters were measured at screening, and at treatment periods 3 and 7: carbohydrate metabolism (glucose, insulin, glycosylated hemoglobin (HbA1C)), adrenal function (total cortisol, cortisol binding globulin (CBG), dehydroepiandrosterone sulfate (DHEAS)), thyroid function (thyroid stimulating hormone, free thyroxine).
Results: Overall, the effect on carbohydrate metabolism was minimal with both study medications. There was a trend for higher glucose and insulin values for the levonorgestrel group at both treatment periods 3 and 7. None of the changes were thought to be clinically relevant. Both preparations had similar small effects on HbA1C values, indicating that carbohydrate metabolism was not affected. No effects were found on thyroid function parameters or DHEAS in either treatment group; however, total cortisol and CBG were slightly higher with desogestrel than with levonorgestrel. These changes were not considered to be clinically relevant. Both treatments were well tolerated.
Conclusions: The effects of both progestogen-only pills on carbohydrate metabolism were minimal and considered to be clinically insignificant. With regard to adrenal and thyroid function, the effects of desogestrel were not significantly different from those of levonorgestrel.