Short‐Term Treatment With Myo‐Inositol and D‐Chiro‐Inositol in 40:1 Ratio Significantly Increases the Number of Hyperandrogenic Women With PCOS Who Menstruate With Respect to 3.6:1 Ratio

Background

Inositol has an established role in the management of patients with polycystic ovary syndrome (PCOS). Two stereoisomers, myo‐inositol (MI) and D‐chiro‐inositol (DCI), are generally employed in a diversity of ratios, although the rationale for choosing one ratio over another is still highly debated. Indeed, a variety of products with different inositol ratios are currently available in the market.

Objective

We intended to compare the efficacy of two formulations, marketed in Italy, containing different inositol ratio—i.e., 40:1 and 3.6:1 MI:DCI.

Methods

We carried out a prospective, open‐label, and randomized comparative evaluation of the efficacy of the two formulations in a population of overweight women with hyperandrogenic PCOS. The presence of menstrual cycle was the primary endpoint, assessed through a menstrual cycle diary. Metabolic and hormonal parameters were recorded at baseline and after 3‐month treatment.

Results

The number of patients with at least one menstrual cycle significantly increased in the group treated with the 40:1 inositol ratio ( p  < 0.05), while no change was observed in the other group. The difference between the groups at the end of the study was also significant ( p  < 0.01). Free testosterone significantly decreased in patients treated with the 40:1 inositol ratio ( p  < 0.001), accompanied by significant increase in serum SHBG ( p  < 0.05—significance was however lost after conservative adjustment for multiple comparisons). We observed variations in the group treated with 3.6:1 ratio, but they failed to reach significance. Metabolic parameters, instead, significantly improved in both study groups.

Conclusions

The 40:1 inositol ratio proved superior to the 3.6:1 ratio in increasing the number of women who menstruate in the short term and should be the preferred choice when restoring menstrual cycle is the primary aim of the treatment for women with hyperandrogenic PCOS.

Trial Registration: ClinicalTrials.gov identifier: NCT06715527