Landmark Study of DCI in Obese PCOS Women

Ovulatory And Metabolic Effects Of D-Chiro-Inositol In The Polycystic Ovary Syndrome

By: John E. Nestler, M.D., Daniela J. Jakubowicz, M.D., Paula Reamer, M.A., Ronald D. Gunn, M.S., And Geoffrey Allan, Ph.D.
New England Journal of Medicine, 1999


Good design: randomized, double-blind, placebo-controlled
Sufficient size: 44 subjects
Statistical analysis was appropriate and sufficiently documented
Reasonable conclusions supported by evidence




This is the landmark DCI clinical trial, published in The New England Journal of Medicine in 1999. Years of research had suggested that DCI would help women with PCOS, and many studies had been performed with animals. But a human trial was necessary to prove that DCI is effective for PCOS.

44 obese women, aged 18 to 40 years, were selected to participate in the study. All of the women had irregular menstrual cycles, high androgen levels, and polycystic ovaries. None of the women had diabetes or thyroid dysfunction.

Half of the women received a placebo; the other half received 1200 mg of DCI once per day. The women received no other treatments, and were advised not to change their diet, exercise routines, or lifestyle to ensure that any results could definitively be attributed to DCI.

The results were dramatic: 18 of the 22 (81%) women in the DCI group ovulated within six weeks, compared to 6 of 22 (27%) in the placebo group. Over eight weeks, there were drastic reductions in insulin, androgens, and triglycerides. There was also a striking increase of SHBG (serum sex-hormone binding globulin).

Some direct quotes from the paper: is known that increasing insulin sensitivity in women with this disorder [PCOS] results in improved ovulatory function and decreased serum androgen concentrations.

We found that the administration of D-chiro-inositol to women with the polycystic ovary syndrome decreased the insulin response to orally administered glucose. ...this decrease was most likely due to an improvement in peripheral insulin sensitivity.

These findings are consistent with an improvement in insulin sensitivity, as demonstrated previously with drugs such as metformin and troglitazone.

CONCLUSIONS: D-chiro-inositol increases the action of insulin in patients with the polycystic ovary syndrome, thereby improving ovulatory function and decreasing serum androgen concentrations, blood pressure, and plasma triglyceride concentrations.


infograph of Nestler Study

PubMed link:

You can read the full article for free here: