Reduction of hyperinsulinemia and insulin resistance by opiate receptor blockade in the polycystic ovary syndrome with acanthosis nigricans

Insulin Secretion in Hypothalamic Obesity: Diurnal Variation and the Effect of Naloxone

This paper has tested the hypothesis that patients with hypothalamic obesity have altered mechanisms controlling insulin secretion when compared to obese patients without hypothalamic injury. Fasting glucose and insulin values were significantly higher in the morning than in the afternoon in the six control obese patients, but there was no diurnal difference in the six patients with hypothalamic obesity (n=6). The control obese subjects showed a diurnal variation in glucose-stimulated insulin secretion, whereas the patients with hypothalamic obesity did not, suggesting that hypothalamic injury had destroyed diurnal rhythms. Naloxone, an opioid antagonist, acutely suppressed fasting insulin in the six patients with essential obesity but had little effect on fasting insulin in the three patients with hypothalamic obesity or in five normal-weight controls. Naloxone increased insulin sensitivity in the obese control patients, but did not affect either insulin secretion or insulin sensitivity in patients with hypothalamic obesity or in normal weight subjects. Our results support the conclusion that hypothalamic obesity disrupts diurnal rhythms, with the suggestion that opioid peptides affect insulin secretion differently in patients with essential obesity as compared to normal weight subjects or those with hypothalamic obesity.

The lack of association between polycystic ovary syndrome and metabolic syndrome: Iranian PCOS prevalence study

OBJECTIVE

This study was designed to evaluate the prevalence of the metabolic syndrome (MetS) and insulin resistance (IR) in a large population-based study in Iran.

RESEARCH DESIGN AND METHODS

Anthropometric measurements, biochemical parameters and IR were compared between 136 polycystic ovary syndrome (PCOS) subjects and 423 healthy controls recruited from among 1126 reproductive aged women (18-45 year). PCOS and MetS were diagnosed using the Rotterdam criteria and Joint Interim Statement, respectively. IR was defined using the homeostatic model assessment-IR).

RESULTS

Among the PCOS subjects, the mean ± SD age, body mass index (BMI) and waist circumference were 31 ± 7·7 years, 26·4 ± 5·8 kg/m(2) and 84 ± 13·3 cm, respectively; corresponding values among healthy controls were 36 ± 7·5 years, 26·4 ± 5·0 kg/m(2) and 85 ± 11·9 cm, respectively. Age and BMI adjusted prevalences of MetS in PCOS subjects and controls were 18·5% (CI 95%, 15·3-21·7%) and 18·3% (CI 95%, 15·1-21·5%), respectively [P = not significant (NS)]. Age and BMI adjusted prevalences of IR in PCOS and healthy controls were 27·2% (CI 95%, 23·5-30·9%) and 24·2% (CI 95%, 20·6-27·8%), respectively (P < 0·01).

CONCLUSIONS

Metabolic syndrome was no more frequent in a representative sample of PCOS Iranian population than in healthy controls. However, the prevalence of IR in PCOS appears to be higher than in controls. It seems that the association between PCOS and MetS needs more consideration.

Normalization of hyperinsulinemia by chronic opioid receptor blockade in hyperandrogenemic women

OBJECTIVE

Evaluation of the effects of naltrexone on hyperinsulinemia and hyperandrogenemia in hyperandrogenemic, hyperinsulinemic women.

DESIGN

Controlled clinical study.

SETTING

Department of Gynecologic Endocrinology and Reproductive Medicine, Center of Obstetrics and Gynecology, Medical University of Innsbruck, Austria.

PATIENT(S)

Thirty-nine hyperandrogenemic, hyperinsulinemic women were studied.

INTERVENTION(S)

Women were treated with naltrexone (50 mg/d) for >or=3 weeks.

MAIN OUTCOME MEASURE(S)

Body mass index (BMI), gonadotropin (LH, FSH) and androgen (T, free T, DHEAS) levels, and plasma levels of glucose, insulin, and C-peptide, during a standard 75-g oral glucose tolerance test (OGTT), were determined before and during chronic opiate receptor blockade.

RESULT(S)

The BMI did not change during therapy. When OGTT was repeated after treatment with naltrexone, glucose levels were not different from those before treatment. Insulin response, however, had dramatically declined. We also observed a significant decrease in the levels of serum androgens.

CONCLUSION(S)

Hyperinsulinemia associated with hyperandrogenemia can be improved or completely abolished by chronic opiate receptor blockade. This observation suggests that endogenous opiates play a critical role in the process leading to hyperinsulinemia in hyperandrogenemia.

Combined oral contraceptives in the treatment of polycystic ovary syndrome

Combined oral contraceptives (COC) are the most often used treatment modality for polycystic ovary syndrome (PCOS). Undisputedly, COC suppress androgen production, thus ameliorating skin androgenic symptoms and improving menstrual dysfunction. On the other hand, there are still many unresolved issues concerning their metabolic effects. COC could decrease insulin sensitivity and deteriorate glucose tolerance, although the negative influence on insulin sensitivity is dependent on other factors (especially obesity) and this need not be expressed in non-obese patients. It is probable that the impairment of glucose tolerance is reversible, as the incidence of diabetes is not increased in past COC users. The effects of COC on the lipid spectrum are dependent on the type of gestagen, but lipid levels usually remain within the reference limits. Combination therapy of COC with weight reduction or insulin sensitizers could further suppress androgen levels and improve metabolic parameters. The establishment of COC after laparoscopic ovarian drilling may further decrease androgen levels. The combination of COC and GnRH analogues is not superior to COC therapy alone. Prospective data about the influence of COC on the risk of diabetes mellitus, coronary artery disease and endometrial cancer in PCOS women are lacking.

The effect of vertical banded gastroplasty on glucose-induced beta-endorphin response

BACKGROUND

beta-Endorphin is an endogenous opioid involved in the regulation of food intake and obesity as well as in insulin metabolism. In this study, we investigated glucose-induced beta-endorphin, insulin, and glucose responsiveness in morbidly obese patients and the effect of surgically induced weight loss.

METHODS

Thirty-two healthy, nondiabetic, morbidly obese patients (body mass index over 40 kg/m2) and 32 normal-weight controls were studied. Serum levels of beta-endorphin, insulin, and glucose were measured under basal conditions and during an oral glucose tolerance test (OGTT) before and 12 months following vertical banded gastroplasty.

RESULTS

Preoperative basal levels of beta-endorphin, insulin, and glucose and their responses during OGTT in obese patients were significantly higher compared with those of controls. After surgery, basal beta-endorphin, insulin, and glucose levels decreased significantly compared with preoperative values. Postoperative basal insulin and glucose levels were similar to those in controls, while beta-endorphin levels remained significantly higher than those of controls. A significant reduction in total responses of beta-endorphin, insulin, and glucose during OGTT was also observed; however, postoperative beta-endorphin and insulin responses remained significantly higher than in controls.

CONCLUSION

Morbidly obese patients have an increased glucose-stimulated response of beta-endorphin, insulin, and glucose which is partially corrected with weight loss following vertical banded gastroplasty.

Polycystic ovary syndrome and insulin resistance: thrifty genes struggling with over-feeding and sedentary life style?

Almost two decades of research have greatly increased our knowledge in the complex field of metabolic aberrations in polycystic ovary syndrome, but still many problems remain unsolved. The statistical association between insulin levels and androgens originally put the focus on possible direct cause-and-effect relationships between these factors. Indeed there is evidence that insulin may affect ovarian functions in multiple ways, presumably in some cases causing anovulation and hyperandrogenism. Clearly, insulin may increase biologically active testosterone through reducing SHBG levels. Conversely, major increases in androgen levels may induce muscular changes leading to reduced insulin-mediated glucose uptake. There are suggestions of increased steroidogenesis in both ovarian and adrenal pathways, with the net result of increased androgen production. There are also findings supporting increased corticosteroid production, which could contribute to insulin resistance directly or through promoting accumulation of abdominal fat, a typical feature of over-weight women with PCOS. Free fatty acids, released in great amounts from abdominal fat, may induce insulin resistance. Insulin resistance may also be due to a primary aberration in the insulin receptor. Putatively increased serine phosphorylation may cause both impairment of the insulin signal and increased 17,20 lyase activity, thus suggesting a common cause for insulin resistance and increased androgen production. There are also findings supporting a high prevalence of beta-cell dysfunction in PCOS, ranging from increased insulin secretion, not explained by insulin resistance or BMI, to failing beta-cell function, mainly in obese women during progress to glucose intolerance and NIDDM. Recent genetic findings also support a multifactorial genesis to PCOS, notably with positive findings both in genes regulating steroidogenesis and insulin secretion. It is suggested that PCOS is the result of "thrifty" genes, providing advantages in times of shortage of nutrition such as muscular strength, moderate abdominal fatness and decreased insulin sensitivity, i.e. an anabolic, energy saving constitution. However, when this constitution is exposed to unlimited food supplies and modern sedentary life style a full-blown PCOS with insulin resistance and infertility is triggered, presumably via several mechanisms, which follow a logical amplification system between two basic anabolic hormones, insulin and testosterone.

Insulin and polycystic ovary syndrome: a new look at an old subject

In recent years the metabolic implications of polycystic ovary syndrome (PCOS) have received a great deal of attention; in fact 50% of women with PCOS are obese and a similar percentage of subjects was found to show exaggerated insulin secretion and reduced insulin-stimulated glucose uptake. The presence of these features in women with PCOS has profound clinical implications in terms of morbidity due to diabetes mellitus, dyslipidemia, hypertension and cardiovascular disease. Moreover, hyperinsulinemia has recently been proposed as a possible independent risk factor for endometrial and breast cancer. In the light of these considerations, the importance of metabolic screening in patients with PCOS in order to improve their quality of life cannot be underestimated. In this review we analyze all the clinical pathologies in which hyperinsulinemia of PCOS could be involved. Furthermore, in order to clarify the possible mechanisms leading to the insulin disorders of the syndrome, we review the available data about the insulin receptor abnormalities, as well as those concerning the insulin resistance and the exaggerated insulin secretion. Finally, we examine the main therapeutic strategies to ameliorate the insulinemic status of PCOS patients in order to potentially be able to prevent the long-term consequences of this syndrome.

Disturbances in insulin secretion and sensitivity in women with the polycystic ovary syndrome

Insulin resistance, defined as a diminished effect of a given dose of insulin on glucose homeostasis, is a highly prevalent feature of women with PCOS. Insulin resistance in PCOS is closely associated with an increase in truncal-abdominal fat mass, elevated free fatty acid levels, increased androgens, particularly free testosterone through reduced SHBG levels, and anovulation. The causes for insulin resistance in PCOS are still unknown. One line of evidence suggests that an increase in truncal-abdominal fat mass and subsequently increased free fatty acid levels induce insulin resistance in women with PCOS. Increased effects of corticosteroids and a relative reduction in oestrogen and progesterone seem to be involved in the aberrant body fat distribution. Conversely, there are also results supporting primary, genetic target cell defects as a cause of insulin resistance in PCOS. An explanation for these seemingly contradictory results could be that the group of women with PCOS is heterogeneous with respect to the primary event in carbohydrate/insulin disturbances. Also insulin secretion in PCOS is characterized by heterogeneity. At one end of the spectrum is a large subgroup of mainly obese women with reduced insulin secretion, which appears to result from failure of the beta cells to compensate for insulin resistance in susceptible women, resulting in glucose intolerance and NIDDM. In the insulin-resistant patients with normal glucose tolerance, most of the hyperinsulinaemia is probably due to secondarily increased insulin secretion and decreased insulin degradation. However, a component of the increased first-phase insulin release is not due to measurable insulin resistance. Notably, this is also found in lean women with normal insulin sensitivity, and is not reversed after weight reduction, in contrast to the findings for insulin resistance. The implications of this enhanced insulin release are not fully clear, but it may tentatively be associated with carbohydrate craving and subsequently increased risks for development of obesity and insulin resistance. It may represent a primary disturbance of insulin secretion in PCOS or may be associated with the perturbed steroid balance in anovulation. The insulin-androgen connection in PCOS appears to be amplified by several different mechanisms, notably in both directions, the initiating event probably varying between individuals. Thus insulin increases the biological availability of potent steroids, primarily testosterone, through the suppression of SHBG synthesis. Insulin is also involved as a progonadotrophin in ovarian steroidogenesis, with the possible net result of interfering with ovulation and/or increasing ovarian androgen production in states of hyperinsulinaemia. Conversely, testosterone may indirectly contribute to insulin resistance through facilitating free fatty acid release from abdominal fat, but perhaps also through direct muscular effects at higher serum levels. It seems likely that this constitution, presumably genetic, would provide evolutionary advantages in times of limited nutrition, given the energy-saving effects of insulin resistance. Hypothetically, hyperinsulinaemia (primary) could provide a stimulus to ensure intake of nourishment, but unlimited food supplies could in some cases initiate a vicious 'anabolic' circle, in which several of the proposed amplifying mechanisms between insulin and androgens--in both directions--could take part.

Plasma beta-endorphin levels and glucose tolerance in patients with chronic renal failure

In order to examine the role of endogenous opioid peptides on glucose metabolism in uraemic patients, plasma concentrations of beta-endorphin, glucose, insulin and C-peptide were determined before and during an oral glucose tolerance test (OGTT) in nine non-dialysed patients with chronic renal failure (CRF). The results are compared with those obtained in a group of age-matched normal subjects. In CRF patients, plasma beta-endorphin fasting values (16.0 +/- 1.9 pmol/l) were significantly higher than those of the controls (6.6 +/- 0.6 pmol/l) and significantly correlated with the degree of renal function impairment. After glucose load, plasma beta-endorphin in CRF patients tended to decline, whereas in normal subjects increased. The fasting and the mean OGTT plasma beta-endorphin values negatively correlated with insulin initial response to glucose, insulin and C-peptide mean OGTT values, but not with glucose OGTT mean values. Data indicate that chronic uraemia induces a significant increase in circulating plasma beta-endorphin levels, with a loss of opioid system responsiveness to glucose. The possibility that this hyper-endorphinism may have a biological importance at least as a contributory factor of impaired glucose tolerance in uraemia may be suggested.

Acute cholinergic blockade with low dose pirenzepine reduces the insulin and glucose responses to a mixed meal in obese women with the polycystic ovary syndrome

OBJECTIVES

Pirenzepine, a selective muscarinic cholinergic antagonist, reduces plasma insulin and plasma glucose responses to a mixed meal in a dose dependent fashion in normals and in patients with non-insulin dependent diabetes. We have studied the effects of pirenzepine on plasma insulin, plasma glucose, growth hormone (GH), androstenedione, testosterone, insulin-like growth factor-I (IGF-I) and IGF binding protein 1 (IGFBP-1) responses to a mixed meal in obese clinically hyperandrogenic women with the polycystic ovary syndrome.

SUBJECTS AND METHODS

Six obese women with polycystic ovary syndrome (BMI range 27.3-39.8 kg/m2) were studied in random sequence, and received either placebo or pirenzepine (single doses of 50, 100, or 200 mg) one hour before a standard test meal. Blood was sampled every 15 minutes for 2 hours after the meal and every 30 minutes thereafter for a total of 4 hours.

RESULTS

Mean fasting plasma insulin concentrations were increased. Peak post-prandial plasma insulin concentrations were reduced significantly by all three doses used. Post-prandial integrated plasma insulin concentrations were reduced by the two higher doses. Peak post-prandial plasma glucose concentrations were also reduced. The late post-prandial GH surge was significantly suppressed by all three doses. However, plasma androstenedione, testosterone, IGF-I and IGFBP-1 concentrations were not significantly different when placebo was compared with pirenzepine 200 mg.

CONCLUSIONS

Acute cholinergic muscarinic blockade with pirenzepine significantly reduces meal stimulated plasma insulin and plasma glucose concentrations in clinically hyperandrogenic women with polycystic ovary syndrome. The ability of pirenzepine to reduce plasma insulin without worsening glycaemia is a particular advantage and may be therapeutically relevant. Further studies are under way to assess the usefulness of pirenzepine in long-term suppression of plasma insulin in this group of patients.

The role of the opioid peptides in the development of hyperinsulinemia in obese women with abdominal body fat distribution

In this study, we investigated the hypothesis that increased opioid activity may be involved in the development of hyperinsulinemia in women with obesity and abdominal body fat distribution. Two groups of nine obese body (body mass index [BMI], 30 to 40 kg/m2) women with abdominal (A-ob) (waist to hip ratio [WHR] greater than 0.85) or gluteo-femoral (F-ob) (WHR greater than or equal to 0.80) fat distribution were examined and compared with eight normal-weight controls. Basal beta-endorphin levels were higher in the A-ob group than in the other groups. Each woman underwent two oral glucose tolerance tests (OGTT, 75 g glucose). A bolus of naloxone (0.8 mg) followed by a constant infusion of naloxone (0.04 mg/kg/h) or saline was also administered during the glucose challenge in random order, and blood samples for glucose, insulin, and C-peptide were collected at regular times after glucose administration. No difference was observed in basal or stimulated glucose concentrations between the three groups, nor between the saline or naloxone study. However, basal and stimulated insulin levels were significantly higher in obese women (particularly in the A-ob group) than in controls. Naloxone administration, however, did not significantly modify insulin and C-peptide glucose-stimulated concentrations in controls and in the F-ob group, whereas it significantly reduced (by approximately 47%) insulin levels in the A-ob group. Partial correlation coefficients showed a significant negative correlation between percent variation of glucose-stimulated insulin incremental areas during the naloxone study and the WHR in all women considered together (r = .544, P less than .025).(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological elevations of plasma beta-endorphin alter glucose metabolism in obese, but not normal-weight, subjects

The present study was undertaken to evaluate the metabolic and hormonal responses to physiologic elevations of plasma beta-endorphin concentrations in both normal-weight and obese healthy subjects. The infusion of synthetic human beta-endorphin (4.5 ng/kg/min) produced the following: (1) in normal-weight subjects, no significant change of plasma glucose and pancreatic hormones (insulin, C-peptide, and glucagon), a significant plasma free fatty acids (FFA) increase, and a suppression of glycerol plasma levels; (2) in obese subjects, significant increases of glucose, insulin, C-peptide, and glucagon, a progressive decline of circulating FFA, and no change in glycerol plasma levels. In obese subjects, the intravenous administration of naloxone, given as a bolus (5 mg injected in 5 minutes) before the start of beta-endorphin infusion, reduced the plasma glucose response to the opioid by approximately half, annulled the pancreatic hormonal responses, and also reduced the FFA, but not glycerol, response. In normal-weight subjects, naloxone pretreatment did not induce any change of the flat glucose and hormonal responses to beta-endorphin, but reversed its effects on circulating FFA and glycerol. These data suggest that physiological elevations of plasma beta-endorphin concentrations produce metabolic and hormonal effects in obese subjects significantly different from those occurring in normal-weight subjects; these effects are partially naloxone-sensitive, suggesting the mediation of endogenous opioid receptors.

Current concepts of beta-endorphin physiology in female reproductive dysfunction

beta-Endorphin has a role in the regulation of the normal menstrual cycle and possibly in the onset of puberty. We have reviewed the evidence pointing to an alteration in this neuropeptide that may contribute to the pathogenesis of various reproductive dysfunctions. Elevated or high levels of beta-endorphin have been associated with exercise-associated amenorrhea, stress-associated amenorrhea, and polycystic ovarian syndrome. Depressed or low levels of beta-endorphin have been associated with PMS and menopause. Alterations in the levels of beta-endorphin may change the pulsatile release of GnRH via noradrenergic and/or dopaminergic pathways. We have primarily focused on beta-endorphin as representative of the endogenous opioid peptides, but other opioid peptides may also contribute to the pathogenesis of various types of reproductive dysfunction. Perhaps it will become possible to characterize and hone our understanding of the function of beta-endorphin and the other substances composing the endogenous opioid peptides. A better understanding of their role in physiological as well as pathophysiological processes may allow for the development of rational approaches to the treatment of specific disorders pertaining to reproduction. Many questions remain unanswered. Among the most relevant are: what is the precise mechanism of action by which beta-endorphin exerts its influence on pulsatile GnRH release? Is there a functional relationship between CNS and peripheral (serum) levels of beta-endorphin? Are the detected changes in beta-endorphin levels merely associated, or are they a cause of a particular disorder? Since it took almost 40 years between the time prostaglandins were first discovered and eventual realization of their clinical application, it may take some time before the beta-endorphin story is complete.

Effect of naloxone on plasma insulin, insulin-like growth factor I, and its binding protein 1 in patients with polycystic ovarian disease

Insulin and insulin-like growth factors (IGFs) stimulate ovarian steroidogenesis, and hyperinsulinemia is often accompanied by hyperandrogenemia in women with polycystic ovarian disease (PCOD). Because opioid peptides are involved in the regulation of insulin secretion, we studied the effect of naloxone-induced opiate receptor blockade on the circulating levels of insulin, IGF-I, and IGF binding protein 1 (IGFBP-1) in 13 nonobese and 7 obese PCOD patients and in 6 healthy subjects. In obese PCOD patients, the mean basal insulin concentration was significantly higher and the IGFBP-1 concentration lower than in nonobese PCOD patients. Plasma IGF-I levels were elevated both in obese and nonobese PCOD patients. After an intravenous bolus of 10 mg naloxone, no significant changes were found in the circulating insulin or IGF-I levels, whereas IGFBP-1 levels decreased in nonobese PCOD patients and remained low in obese PCOD patients. No significant decrease was found in healthy subjects. These results suggest that, in addition to insulin, endogenous opioids are involved in the regulation of serum IGFBP-1 level.

Hirsutism: definitions and etiology

Hirsutism as a sign of hyperandrogenism is a common endocrinological disorder in women. Its spectrum varies from mild forms with dominating psychic component to severe forms associated with virilization. The severity should be assessed by semiobjective scoring systems, the use of which also allows the systematic follow-up of the results of treatment. An increase in serum androgen levels or an increased turnover of androgens can be detected in most patients. Enhanced peripheral conversion of androgens to locally acting androgen also leads to hirsutism. The thorough investigation of the endocrinological milieu is required to rule out androgen producing neoplasms. In most patient, however, disturbances are functional, among which polycystic ovary syndrome is the commonest. It is a disorder exhibiting a complexity of changes in endocrinological interactions. Besides inappropriate gonadotropin secretion insulin and insulin like growth factor are also involved. The opioidergic system also seems to be affected. Polycystic ovary syndrome is also associated with obesity and infertility, both of which require attention.

Response of plasma beta-endorphin and insulin to oral glucose tolerance test in non-obese women with polycystic ovaries

Increased responses of plasma insulin and endorphins to the oral glucose tolerance test (oGTT) have earlier been found in obese women. We studied responses of immunoreactive beta-endorphin (ir beta-E) and insulin in plasma to the oGTT in 8 non-obese women with polycystic ovaries (PCO) and in 10 healthy women. An additional control group consisted of 5 healthy women who were fasting during the study period. In the PCO group the insulin and glucose responses to the oGTT were increased, and an increase of ir beta-E from 5.9 +/- 1.5 to 8.6 +/- 2.8 pmol/l was found during the 1st half-hour period of the oGTT. In contrast, no significant change was found during the oGTT in healthy women (3.2 +/- 0.5 and 2.7 +/- 0.65 pmol/l, respectively), and in the fasting control women the mean ir beta-E level (+/- SE) decreased, from 4.5 +/- 1.2 to 3.6 +/- 1.1 pmol/l. These findings revealed increased responses of both plasma ir beta-E and insulin to the oGTT in non-obese women with PCO but their possible causal relationship remained unsolved.

Androgen levels during sequential insulin euglycemic clamp studies in patients with polycystic ovary disease

It is postulated that insulin may play a role in the regulation of ovarian androgen production. In order to test the possible interrelation between serum insulin levels and androgen production, sequential euglycemic insulin clamp (Mode 9:1 on Biostator, insulin infusion rate: 0.1; 0.2 and 0.4 U/kg b. wt/h, each rate for 90 min, BC = 80 mg/dl) was done in 6 patients with polycystic ovary disease and normal glucose tolerance. Insulin, C-Peptide, testosterone and dehydroepiandrosterone-sulphate were measured in 0, 70, 80, 90, 160, 170, 180, 250, 260 and 270 min. Significant suppression of C-Peptide levels were achieved (0 min vs 270 min = 0.81 + 0.25 vs 0.15 + 0.20 nmol/l; P less than 0.05). Basal insulin as well as the mean plateau for each insulin infusion rate were as follows: 28 + 9; 248 + 119; 427 + 69 and 524 + 77 microU/l. There was significant testosterone increase at the end of insulin infusion (0 vs 270 min = 4.8 + 1.2 vs 8.1 + 1.7 nmol/l; P less than 0.05). There were no significant changes in dehydroepiandrosterone-sulphate levels during clamp studies (0 vs 270 min = 1055 + 133 vs 913 + 114 ng/ml; P greater than 0.05). It is concluded that acute insulin infusion under the condition of sequential euglycemic clamp could increase androgen production in the ovaries of patients with PCO.