***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Obese women with the polycystic ovary syndrome are relatively unresponsive to the induction of ovulation by clomiphene . We hypothesized that reducing insulin secretion by administering metformin would increase the ovulatory response to clomiphene . METHODS We performed oral glucose-tolerance tests before and after the administration of 500 mg of metformin or placebo three times daily for 35 days in 61 obese women with the polycystic ovary syndrome . Women who did not ovulate spontaneously were then given 50 mg of clomiphene daily for five days while continuing to take metformin or placebo .  Serum progesterone was measured on days 14 , 28 , 35 , 44 , and 53 , and ovulation was presumed to have occurred if the concentration exceeded 8 ng per milliliter ( 26 nmol per liter ) on any of these days . RESULTS Twenty-one women in the metformin group and 25 women in the placebo group were given clomiphene because they did not ovulate spontaneously during the first phase of the study . Among the 21 women given metformin plus clomiphene , the mean ( + /-SE ) area under the serum insulin curve after oral glucose administration decreased from 6745+/-2021 to 3479+/-455 microU per milliliter per minute ( 40.5+/-12.1 to 20.9+/-2.7 nmol per liter per minute , P=0.03 ) , but it did not change significantly in the 25 women given placebo plus clomiphene . Nineteen of the 21 women ( 90 percent ) who received metformin plus clomiphene  ovulated ( mean peak serum progesterone concentration , 23.8+/-3.4 ng per milliliter [ 7.6+/-10.9 nmol per liter ] ) . Two of the 25 women ( 8 percent ) who received placebo plus clomiphene  ovulated ( P<0.001 ) . Overall , 31 of the 35 women ( 89 percent ) treated with metformin  ovulated spontaneously or in response to clomiphene  , as compared with 3 of the 26 women ( 12 percent ) treated with placebo . CONCLUSIONS The ovulatory response to clomiphene can be increased in obese women with the polycystic ovary syndrome by decreasing insulin secretion with metformin Abdominal obesity and hyperinsulinemia play a key role in the development of the polycystic ovary syndrome ( PCOS ) . Dietary-induced weight loss and the administration of insulin-lowering drugs , such as metformin , are usually followed by improved hyper and rogenism and related clinical abnormalities . This study was carried out to evaluate the effects of combined hypocaloric diet and metformin on body weight , fat distribution , the glucose-insulin system , and hormones in a group of 20 obese PCOS women [ body mass index ( BMI ) > 28 kg/m2 ] with the abdominal phenotype ( waist to hip ratio > 0.80 ) , and an appropriate control group of 20 obese women who were comparable for age and pattern of body fat distribution but without PCOS . At baseline , we measured sex hormone , sex hormone-binding globulin ( SHBG ) , and leptin blood concentrations and performed an oral glucose tolerance test and computerized tomography ( CT ) at the L4-L5 level , to measure sc adipose tissue area ( SAT ) and visceral adipose tissue area . All women were then given a low-calorie diet ( 1,200 - 1,400 kcal/day ) alone for one month , after which anthropometric parameters and CT scan were newly measured . While continuing dietary treatment , PCOS women and obese controls were subsequently placed , in a r and om order , on metformin ( 850 mg/os , twice daily ) ( 12 and 8 , respectively ) or placebo ( 8 and 12 , respectively ) , according to a double-blind design , for the following 6 months . Blood tests and the CT scan were performed in each woman at the end of the study while they were still on treatment . During the treatment period , 3 women of the control group ( all treated with placebo ) were excluded because of noncompliance ; and 2 PCOS women , both treated with metformin , were also excluded because they became pregnant . Therefore , the women cohort available for final statistical analysis included 18 PCOS ( 10 treated with metformin and 8 with placebo ) and 17 control women ( 8 treated with metformin and 9 with placebo )  . The treatment was well tolerated . In the PCOS group , metformin therapy improved hirsutism and menstrual cycles significantly more than placebo .  Baseline anthropometric and CT parameters were similar in all groups . Hypocaloric dieting for 1 month similarly reduced BMI values and the waist circumference in both PCOS and control groups , without any significant effect on CT scan parameters . In both PCOS and control women , however , metformin treatment reduced body weight and BMI significantly more than placebo . Changes in the waist-to-hip ratio values were similar in PCOS women and controls , regardless of pharmacological treatment . Metformin treatment significantly decreased SAT values in both PCOS and control groups , although only in the latter group were SAT changes significantly greater than those observed during the placebo treatment . On the contrary , visceral adipose tissue area values significantly decreased during metformin treatment in both PCOS and control groups , but only in the former was the effect of metformin treatment significantly higher than that of placebo .  Fasting insulin significantly decreased in both PCOS women and controls , regardless of treatment , whereas glucose-stimulated insulin significantly decreased only in PCOS women and controls treated with metformin . Neither metformin or placebo significantly modified the levels of LH , FSH , dehydroepi and rosterone sulphate , and progesterone in any group , whereas testosterone concentrations decreased only in PCOS women treated with metformin .  SHBG concentrations remained unchanged in all PCOS women ; whereas in the control group , they significantly increased after both metformin and placebo .  Leptin levels decreased only during metformin treatment in both PCOS and control groups . ( ABSTRACT TRUNCATED BACKGROUND Insulin resistance and increased ovarian cytochrome P450c17 alpha activity are both features of the polycystic ovary syndrome . P450c17 alpha , which is involved in and rogen bio synthesis , has both 17 alpha-hydroxylase and 17,20-lyase activities . Increased activity of this enzyme results in exaggerated conversion of progesterone to 17 alpha-hydroxyprogesterone in response to stimulation by gonadotrophin . We hypothesized that hyperinsulinemia stimulates ovarian P450c17 alpha activity . METHODS We measured fasting serum steroid concentrations and the response of serum 17 alpha-hydroxyprogesterone to leuprolide , a gonadotrophin-releasing hormone agonist , and performed oral glucose-tolerance tests before and after oral administration of either metformin ( 500 mg three times daily ) or placebo for four to eight weeks in 24 obese women with the polycystic ovary syndrome . RESULTS In the 11 women given metformin , the mean ( + /- SE ) area under the serum insulin curve after oral glucose administration decreased from 9303 + /- 1603 to 4982 + /- 911 microU per milliliter per minute ( 56 + /- 10 to 30 + /- 6 nmol per liter per minute ) ( P = 0.004 ) . This decrease was associated with a reduction in the basal serum 17 alpha-hydroxyprogesterone concentration from 135 + /- 21 to 66 + /- 7 ng per deciliter ( 4.1 + /- 0.6 to 2.0 + /- 0.2 nmol per liter ) ( P = 0.01 ) and a reduction in the leuprolide-stimulated peak serum 17 alpha-hydroxyprogesterone concentration from 455 + /- 54 to 281 + /- 52 ng per deciliter ( 13.7 + /- 1.6 to 8.5 + /- 1.6 nmol per liter ) ( P = 0.01 ) . The serum 17 alpha-hydroxyprogesterone values increased slightly in the placebo group . In the metformin group , the basal serum luteinizing hormone concentration decreased from 8.5 + /- 2.2 to 2.8 + /- 0.5 mlU per milliliter ( P = 0.01 ) , the serum free testosterone concentration decreased from 0.34 + /- 0.07 to 0.19 + /- 0.05 ng per deciliter ( 12 + /- 3 to 7 + /- 2 pmol per liter ) ( P = 0.009 ) , and the serum sex hormone-binding globulin concentration increased from 0.8 + /- 0.2 to 2.3 + /- 0.6 microgram per deciliter ( 29 + /- 7 to 80 + /- 21 nmol per liter ) ( P < 0.001 ) . None of these values changed significantly in the placebo group . CONCLUSIONS In obese women with the polycystic ovary syndrome , decreasing serum insulin concentrations with metformin reduces ovarian cytochrome P450c17 alpha activity and ameliorates hyper and rogenism BACKGROUND This study aims to evaluate the impact of metformin on ovarian response when co-administered during recombinant (r)FSH using the low-dose step-up protocol in clomiphene citrate-resistant polycystic ovarian syndrome ( PCOS ) patients with normal glucose tolerance . METHODS AND RESULTS Thirty-two patients were r and omized to metformin  ( n = 16 ) and placebo  ( n = 16 ) groups . Hormonal assessment , a 75 g oral glucose tolerance test ( OGTT ) and a frequently sample d i.v . glucose tolerance test ( FSIGTT ) were performed before and after oral administration of metformin ( 850 mg twice daily ) or placebo for 6 weeks . Recombinant FSH treatment was undertaken , thereafter , in women who did not ovulate on metformin ( n = 10 ) or placebo ( n = 15 ) . There was no significant change in all insulin sensitivity indices in both groups . The only change noted was a decline in mean serum free testosterone concentration in the metformin group ( P = 0.049 ) . One patient on placebo and six patients on metformin  ovulated spontaneously ( P < 0.05 ) . All parameters of ovarian response were comparable between the two groups during rFSH treatment . Combining the 6 week placebo or metformin-only period with a single rFSH treatment cycle , the overall ovulation rates were 75 and 94 % in the placebo and metformin groups respectively ( P > 0.05 ) . The respective figures for pregnancy were 6.3 and 31.3 % ( P > 0.05 ) . CONCLUSIONS Metformin may restore ovulation with no improvement on insulin resistance in clomiphene citrate-resistant PCOS patients with normal glucose tolerance , but has no significant effect on ovarian response during rFSH treatment OBJECTIVE To evaluate the effect of metformin therapy on hyper and rogenism , insulin resistance , cervical scores , ovulation , and pregnancy rates in clomiphene citrate-resistant women with polycystic ovary syndrome ( PCOS ) . DESIGN Prospect i ve , r and omized , double-blind , placebo-controlled study . SETTING Infertility clinic of a tertiary referral center . PATIENT(S ) Fifty-six women with clomiphene citrate-resistant PCOS . INTERVENTION(S ) Two cycles of oral metformin therapy ( 850 mg , twice daily ) in group I and placebo therapy ( twice daily ) in group II . Clomiphene citrate ( 100 mg/day ) on cycle days 3 - 7 of the second cycle in both groups . MAIN OUTCOME MEASURE(S ) Insulin , T , DHEAS , FSH , LH , body mass index ( BMI ) , waist-to-hip ratio , endometrial thickness , cervical score , ovulation , and pregnancy rates in clomiphene-induced cycles after metformin therapy . RESULT ( S ) Metformin therapy result ed in a significant decrease in total T , LH level , LH/FSH ratio , insulin resistance , and mean BMI . No difference in waist-to-hip ratio , DHEAS level , and fasting insulin level was observed . Clomiphene citrate induction result ed in higher ovulation rates and thicker endometrium in the metformin group than in the placebo group . There was higher cumulative pregnancy rate in the metformin group ; however , there was no significant difference in the pregnancy rate between the two groups . CONCLUSION ( S ) Metformin therapy not only decreases hyper and rogenism and insulin resistance but also improves ovulation rates , cervical scores , and pregnancy rates in clomiphene citrate-resistant women with PCOS We hypothesized that hyperinsulinemia contributes to early pregnancy loss in the polycystic ovary syndrome by adversely affecting endometrial function and environment . Serum glycodelin , a 
    Output:
    
Metformin has an effect in reducing fasting insulin concentrations , blood pressure , and low density lipoprotein cholesterol .
We found no evidence of any effect on body mass index or waist : hip ratio .
Metformin was associated with a higher incidence of nausea , vomiting , and other gastrointestinal disturbance .
CONCLUSIONS Metformin is an effective treatment for anovulation in women with polycystic ovary syndrome .
No data are available regarding the safety of metformin in long term use in young women and only limited data on its safety in early pregnancy .