Background Women with the polycystic ovary syndrome have insulin resistance
and hyperinsulinemia, possibly because of a deficiency of a D-chiro-inosit
ol-containing phosphoglycan that mediates the action of insulin. We hypothe
sized that the administration of D-chiro-inositol would replenish stores of
the mediator and improve insulin sensitivity.
Methods We measured steroids in serum and performed oral glucose-tolerance
tests before and after the oral administration of 1200 mg of D-chiro-inosit
ol or placebo once daily for six to eight weeks in 44 obese women with the
polycystic ovary syndrome. The serum progesterone concentration was measure
d weekly to monitor for ovulation.
Results In the 22 women given D-chiro-inositol, the mean (+/-SD) area under
the plasma insulin curve after the oral administration of glucose decrease
d from 13,417+/-11,572 to 5158+/-6714 mu U per milliliter per minute (81+/-
69 to 31+/-40 nmol per liter per minute) (P = 0.007; P=0.07 for the compari
son of this change with the change in the placebo group); glucose tolerance
did not change significantly. The serum free testosterone concentration in
these 22 women decreased from 1.1+/-0.8 to 0.5+/-0.5 ng per deciliter (38/-28 to 17+/-17 pmol per liter) (P = 0.006 for the comparison with the chan
ge in the placebo group). The women's diastolic and systolic blood pressure
decreased by 4 mm Hg (P < 0.001 and P = 0.05, respectively, for the compar
isons with the changes in the placebo group), and their plasma triglyceride
concentrations decreased from 184+/-88 to 110+/-61 mg per deciliter (2.1+/
-0.2 to 1.2+/-0.1 mmol per lit er) (P = 0.002 for the comparison with the c
hange in the placebo group). None of these variables changed appreciably in
the placebo group. Nineteen of the 22 women who received D-chiro-inositol
ovulated, as compared with 6 of the 22 women in the placebo group (P < 0.00
1).
Conclusions D-Chiro-inositol increases the action of insulin in patients wi
th the polycystic ovary syndrome, thereby improving ovulatory function and
decreasing serum androgen concentrations, blood pressure, and plasma trigly
ceride concentrations, (N Engl J Med 1999;340:1314-20.) (C)1999, Massachuse
tts Medical Society.